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Fibroblast Growth Factor-23 and Cardiac Magnetic Resonance Indices of
Myocardial Fibrosis in the Multi-Ethnic Study of Atherosclerosis
By
MOHAMED FAHER ALMAHMOUD, MD
A Thesis submitted to the Graduate Faculty of
WAKE FOREST UNIVERSITY GRADUATE SCHOOL OF ARTS AND SCIENCES
In Partial Fulfillment of the Requirements
for the Degree of
MASTER OF SCIENCE
Clinical Population and Translational Sciences
May 2016
Winston-Salem, North Carolina
Approved by:
David M. Herrington, MD, Mentor/Advisor
Beverly M. Snively, PhD
Jennifer Hawthorne Jordan, PhD, MS
i
ACKNOWLEDGMENTS
I am wholeheartedly grateful to Dr. David Herrington for his continued support,
guidance and mentorship during this fellowship and while preparing this thesis. I am very
thankful for every minute he spent teaching me by example what it means to be dedicated
and what it takes to be a successful clinical investigator. I am also grateful to Dr. Waqas
Qureshi who guided me to this excellent program and for being always available for any
questions. I am also grateful and appreciative of the time and support by Dr. Beverly
Snively who taught me basics of statistics. Thank you for reviewing every detail in this
work and for the thorough advices. I am also grateful to Dr. Jennifer Jordan for all her
support and encouragement. Thank you for answering my questions about the technical
basics of cardiac magnetic resonance imaging and T1 mapping. My strongest
appreciation and gratefulness to the CPTS program and the faculty who put every effort
to make sure I receive the best teaching I need to excell in all aspects of research. I would
also like to acknowledge Karen Blinson, Randi Sullivan, and Georgia Saylor for all their
assistance and support. My greatest gratitude goes to my mother Dr. Elham Tajeddin and
to my father Dr. Jamal Almahmoud. Thank you for inspiring me to seek the best
education and for supporting me during my research adventures. Thank you for being my
role models of dedication and hard work. And finally, I am most grateful to my wife, Dr.
Khulood Raslan, for her love and support at every step of my career.
ii
TABLE OF CONTENTS
LIST OF ILLUSTRATIONS AND TABLES……………………………………………V
LIST OF ABBREVIATIONS…………………………………………………………...Vii
ABSTRACT……………………………………………………………………………Viii
CHAPTER ONE: BACKGROUND………………………………………………………1
A. Introduction………………………………………………………………………..1
B. Definition of CKD………………………………………………………………...2
C. Cardiovascular disease in CKD population……………………………………….3
D. The pathophysiology of CVD in CKD……………………………………………4
E. Myocardial fibrosis in CKD………………………………………………………5
F. Fibroblast growth factor-23 in individuals with CKD……………………………9
G. The relationship between FGF-23 and all-cause and cardiovascular mortality….10
H. The role of FGF-23 in the pathogenesis of CVD in individuals with CKD……..10
I. Cardiac Magnetic Resonance indices of myocardial fibrosis……………………10
J. FGF-23 and CMR………………………………………………………………..15
K. Conceptual Model………………………………………………………………..15
L. Knowledge gap…………………………………………………………………..17
M. Aims and Hypotheses……………………………………………………………18
N. Methods………………………………………………………………………….19
O. References………………………………………………………………………..20
iii
CHAPTER TWO: MANUSCRIPT
A. KEYWORDS…………………………………………………………………….25
B. ABSTRACT……………………………………………………………………...26
Background………………………………………………………………………26
Methods…………………………………………………………………………..26
Results……………………………………………………………………………26
Conclusion……………………………………………………………………….27
C. INTRODUCTION……………………………………………………………….28
D. METHODS………………………………………………………………………29
Study population…………………………………………………………………29
Study procedure: CMR imaging…………………………………………………30
Measurement of serum FGF-23 concentrations………………………………….32
Statistical Analysis……………………………………………………………….32
E. RESULTS ……………………………………………………………………….34
F. DISCUSSION……………………………………………………………………35
G. LIMITATIONS…………………………………………………………………..38
H. CONCLUSION…………………………………………………………………..39
I. TABLES AND FIGURES……………………………………………………….40
J. SUPPLEMENTAL MATERIAL………………………………………………...44
K. REFERENCES…………………………………………………………………..45
iv
CAPTER 3: ANCILLARY ANLAYSES………………………………………………..49
A. ABSTRACT………………………….…………………………………………..50
B. INTRODUCTION……………………………………………………………….52
C. METHODS……………………….……………………………………………...52
Study population…………………………………………………………………53
Study procedures: CMR imaging………………………………………………...54
Measurement of serum FGF-23 concentrations………………………………….54
Ascertainment of heart failure events……………………………………………54
Statistical Analysis……………………………………………………………….55
D. RESULTS………………………………………………………………………..56
E. DISCUSSION……………………………………………………………………58
F. LIMITATIONS…………………………………………………………………..61
G. CONCLUSION…………………………………………………………………..61
H. TABLES AND FIGURES……………………………………………………….62
I. SUPPLEMENTAL MATERIAL………………………………………………...66
J. REFERENCES...………………………………………………………………...68
CURRICULUM VITAE…………………………………………………………………70
v
LIST OF ILLUSTRATIONS AND TABLES
CHAPTER ONE
Figure 1. Histological changes of the myocardial cells in CKD
Figure 2. Diffuse interstitial myocardial fibrosis in CKD (histologic evidence)
Figure 3. Patterns of myocardial fibrosis in CKD on cardiac magnetic resonance imaging
Figure 4. Regulation of FGF-23
Figure 5. Expected concentration range of FGF-23 as a function of eGFR
Figure 6. Conceptual model of the role of FGF-23 in the development of heart failure
CHAPTER TWO
Table I. Baseline characteristics by Fibroblast Growth Factor-23 quartiles
Table II. CMR indices of myocardial fibrosis by gender
Table III. Associations of FGF-23 with native myocardial T1 mapping, 12-min post-
contrast T1 mapping, and extracellular volume
Figure 1. Participant enrolment in the current study
Figure 2. Associations between serum FGF-23 quartiles and native myocardial T1
mapping, 12-min post-contrast myocardial T1 mapping and ECV
vi
SUPPLEMENTAL MATERIAL
Supplemental Table 1: Baseline participant’s characteristics by Fibroblast Growth
Factor-23 Quartile for the participants with measured ECV
CHAPTER THREE
Table I. Baseline characteristics by Fibroblast Growth Factor-23 quartiles
Table IIA. Association of FGF-23 and incident heart failure, HFrEF and HFpEF.
Table IIB. Association of FGF-23 and incident heart failure, HFrEF and HFpEF (Hazard
ratios per FGF-23 quartiles)
Figure I. Hazards ratios of the associations of FGF-23 quartiles with incident heart
failure, HFrEF and HFpEF.
Figure 2. Higher FGF-23 levels are associated with increased risk of incident heart
failure. Participants were stratified into quartiles of FGF-23. (Kaplan-Meier curve with
95% Hall-Wellner Bands and log-rank test). Notice the Y axis start from 90% survival, X
axis is the time to heart failure event (days).
Figure 3A. Higher FGF-23 levels are associated with increased risk of incident HFrEF.
Participants were stratified into quartiles of FGF-23. (Kaplan-Meier curve with 95%
Hall-Wellner Bands and log-rank test).
Figure 3B. Higher FGF-23 levels are associated with increased risk of incident HFpEF.
Participants were stratified into quartiles of FGF-23. (Kaplan-Meier curve with 95%
Hall-Wellner Bands and log-rank test).
Supplemental Table 1. Associations of FGF-23 and incident heart failure, HFrEF and
HFpEF stratified by gender (Hazard ratios per doubling of FGF-23).
Supplemental Table 2A. Associations of FGF-23 and incident heart failure, HFrEF and
HFpEF overall and stratified by gender without adjustment for LV mass.
Supplemental Table 2B. Associations of FGF-23 and incident heart failure, HFrEF and
HFpEF overall and stratified by gender with adjustment for LVH-ECG.
vii
LIST OF ABBREVIATIONS
CAD Coronary artery disease
CKD Chronic kidney disease
CKD-MBD Chronic kidney disease-Metabolic Bone disease
CMR Cardiovascular magnetic resonance
CV Cardiovascular
DE Delayed enhancement
ECV Extracellular volume
eGFR estimated Glomerular filtration rate
FGF-23 Fibroblast Growth Factor-23
HFpEF Heart failure with preserved ejection fraction
HFrEF Heart failure with reduced ejection fraction
LGE Late gadolinium enhancement
LV left ventricle
MESA Multi-Ethnic Study of Atherosclerosis
MOLLI Modified Look-Locker inversion recovery
MRI Magnetic resonance imaging
viii
ABSTRACT
In this thesis, we will evaluate the association of Fibroblast Growth Factor-23
(FGF-23) with myocardial fibrosis using cardiovascular magnetic resonance (CMR)
imaging techniques. Higher levels of Fibroblast Growth Factor-23 (FGF-23) have been
linked to increased risk of all-cause mortality, cardiovascular mortality, left ventricular
hypertrophy and heart failure. Histologic studies on rats suggest an association between
higher levels of FGF-23 with myocardial fibrosis. However, it is unknown whether such
relationship exists in humans.
We hypothesized that higher levels of FGF-23 would be associated with CMR indices of
myocardial fibrosis. We performed analyses of the association of FGF-23 with pre-and
post-contrast T1 mapping and extracellular volume (ECV) in participants from the Multi-
Ethnic Study of Atherosclerosis (MESA). The first chapter of this thesis will be a
literature review and will discuss the pathogenesis of myocardial fibrosis in individuals
with high levels of FGF-23 such as patients with chronic kidney disease (CKD). The
second chapter will be a manuscript of the associations of FGF-23 with CMR indices of
myocardial fibrosis. The third chapter is comprised of ancillary studies and discussion of
the association of serum FGF23 with incident heart failure with preserved ejection
fraction (HFpEF) and with reduced ejection fraction (HFrEF).
1
CHAPTER ONE: BACKGROUND
Introduction
Heart failure is common among patients with chronic kidney disease (CKD), and
is associated with increased mortality in this population.1 CKD patients have several
derangements of the metabolism of calcium and phosphate that are called metabolic bone
disease (CKD-MBD).2 These derangements lead ultimately to elevated blood levels of
fibroblast growth factor (FGF-23). Several studies showed the association between
elevation of FGF-23 and the development of heart failure.3,4
For example, Kestenbaum et
al. demonstrated an increased risk of incident heart failure with higher concentrations of
serum FGF-23 in a multi-ethnic middle aged population free of heart disease at baseline.3
The same relationship was shown to exist by Scilla et al. in a population with chronic
kidney disease stage 2-4.4 We aim to study the mechanism in which FGF-23 affects the
myocardium, specifically to confirm the findings of animal studies which link higher
levels of FGF-23 with increased myocardial fibrosis.5
Myocardial fibrosis is a common endpoint in a variety of cardiac diseases.6
Diffuse myocardial fibrosis occurs as a part of normal aging;7 however, this process is
accelerated in many diseases.8-10
This diffuse fibrosis is associated with worsening
ventricular function and increased ventricular stiffness and has independent predictive
value for major cardiac events and increased all-cause mortality.11-15
FGF-23 is a hormone secreted by osteoblasts/osteoclasts. It functions as a
phosphaturic factor in the renal tubules and a regulator of parathyroid hormone, thus
regulating calcium and phosphate homeostasis. Higher serum levels of FGF-23 were
2
shown to be associated with a variety of cardiovascular diseases. For example,
Kestenbaum et al. showed that higher serum FGF-23 concentrations are associated with
incident heart failure, left ventricular hypertrophy and coronary disease events.3
Recently, FGF-23 has been shown to be associated with myocardial fibrosis and left
ventricular hypertrophy in animal studies.16,17
The best available non-invasive method of examining myocardial fibrosis is
contrast-enhanced cardiac magnetic resonance (CMR) through T1 mapping. This
technique facilitates the quantification of diffuse myocardial fibrosis measured as the
extracellular volume fraction (ECV).
We propose to examine the association of serum FGF-23 with myocardial fibrosis in the
Multi-Ethnic Study of Atherosclerosis (MESA) using baseline serum FGF-23 and CMR
indices of myocardial fibrosis including ECV measurements and CMR-T1 mapping.
Definition of CKD
CKD is characterized by alterations in the kidney function for a minimum of 3
months. CKD is usually asymptomatic in the early stages.18
Symptoms generally are
related to complications of CKD that usually occur in the late stages. These
complications include cardiovascular disease (CVD),19
anemia,20
infectious
complications, neuropathy and abnormalities related to mineral bone metabolism.2
CKD was classified into five stages according to the National Kidney Foundation
criteria18
. This classification is based on both kidney function and structure. The
glomerular filtration rate (GFR) is used most commonly to assess function. For an
individual to be diagnosed with CKD, he/she must have at least two separate
3
measurements of GFR >90 days apart that are in the abnormal range (GFR<60
mL/min/1.73m2). Since many cases of kidney damage present with preserved GFR, other
markers of kidney damage can be used such as albuminuria, proteinuria, hematuria or
structural abnormalities. Thus, many patients with normal GFR with evidence of kidney
damage are considered to have CKD21
.
CKD has major prognostic implications22
, which include increased all-cause
mortality in patients with CKD compared with those without CKD. Most of the increased
mortality is attributed to increased cardiovascular events. The increased risk of
cardiovascular events is partly due to increased prevalence of traditional cardiovascular
risk factors such as hypertension, diabetes mellitus and also due to direct increased
cardiovascular risk from non-traditional risk factors such as anemia, malnutrition,
inflammation, retention of toxins and CKD-MBD.23,24
The advanced stages of CKD
which is classified as end stage renal disease (ESRD) is associated with even higher risk
of all-cause mortality compared with early stages of CKD.19
Cardiovascular disease in CKD population
CKD is increasingly recognized as an important risk factor for cardiovascular
(CV) mortality.25,26
Recent registry data from the US Renal Data System show that >40%
of ESRD deaths were due to CVD.1
The evidence of the relationship between renal dysfunction and adverse CV
events was first recognized in the dialysis population in whom incidence of CV mortality
is strikingly high. Approximately 50% of individuals with ESRD die from a CV
cause.27,28
In fact, the prevalence of CV disease is already high by the time patients reach
4
ESRD. For example, 40% of patients who have started dialysis have evidence of
coronary artery disease, and 85% of these patients have abnormal left ventricular
structure and function.29
Furthermore, left ventricular hypertrophy (LVH) was found to
be common in patients with CKD even before they progress to dialysis, and that the
prevalence of LVH correlates with the degree of renal functional impairment.30,31
This early link between CKD and CV events was further studied and was found to
follow graded correlation with decreasing level of glomerular filtration rate (GFR). In a
study by Go et al. showed a stepwise increase in the rate of mortality, CV events and
increased hospitalization. With the reference cohort with (GFR>60 mL/min), the adjusted
hazard ratio for death from any cause and any CV events increased to 1.2 and 1.4,
respectively, for GFR between 45 to 59 mL/min; 1.8 and 2.0 for GFR between 30 to 44
mL/min; 3.2 and 2.8 for GFR 15 to 29 mL/min; and 5.9 and 3.4 for GFR <15 mL/min.19
The pathophysiology of CVD in CKD
Even though patients with CKD have accelerated atherosclerosis and vascular
calcification, more patients die from arrhythmias (both atrial and ventricular), sudden
death, and congestive heart failure, than myocardial infarction1. Indeed, 50% of ESRD
patients suffer from heart failure (HF), thus forming the predominant cardiac abnormality
observed in CKD. It is a common perception that HF in CKD is secondary to vascular
comorbid conditions such as ischemic heart disease (IHD), hypertension and diabetes
mellitus, but it is becoming apparent that primary CKD is an independent risk factor for
incident HF even in non-diabetic and normotensive patients32
.
5
LVH in CKD is a pathologic process and unlike physiologic adaptations to
increased workload (e.g. “athletes heart”), is accompanied by fibrosis, which is attributed
to conditions related to the uremic milieu, including increased levels of parathyroid
hormone, endothelin, aldosterone, catecholamines, cardiotonic steroids and fibroblast
growth factors. In addition to fibrosis and cardiomyocyte hypertrophy, histological
changes of the heart in CKD also include myocyte apoptosis/necrosis resulting in
myocyte number reduction, and microvascular abnormalities such as arteriolar wall
thickening and decrease in the number of capillaries33-36
.
Myocardial fibrosis in CKD:
1- Histologic evidence
Diffuse myocardial interstitial widening and fibrosis is common in patients with
CKD.37
Several histological studies have shown increased myocardial fibrosis that is not
explained by other risk factors such as hypertension and/or diabetes. Experimental studies
have showen that interstitial fibrosis occur early after subtotal nephrectomy in the
absence of myocyte necrosis.38
Interstital deposition of collagen type I was associated
with swelling of interstitial cells – both cytoplasm and nuclei; in contrast, nuclear and
cytoplasmic volumes of endothelial cells were unchanged (Figure 1).
6
Figure 1: Histological changes of the myocardial cells in CKD
A. Myocardial interstitial cells of a control animal (electron micrograph, magnification 12,100:1). Cytoplasm without evidence of cell
activation. B. Activated interstitial cell of uremic rat three weeks after 5/6 nephrectomy (magnification 12,300:1). Note the increased
cytoplasm. Note the Abundant endoplasmic reticulum and Golgi complex and the numerous cytoskeletal filaments within the
cytoplasm.
Adapted from Mall et al. Kidney International, Vol.33 (1988), pp. 804-811
Furthermore, Aoki et al. demonstrated the pathologic characteristics of the heart of
dialysis patients with dilated cardiomyopathy which includes diffuse interstitial fibrosis
and severe myocyte hypertrophy with occasional disarray.36
In addition, the extent of the
left ventricular fibrosis was shown to be a strong predictor of cardiovascular mortality
(figure 2). The 3-year event-free cumulative survival rate for cardiac death was 42% in
dialysis patients with 30% or more fibrosis, whereas it was 82% in dialysis patients that
had less than 30% fibrosis (p=0.03). 36
7
Figure 2: Diffuse interstitial myocardial fibrosis in CKD (histologic evidence)
A 56-year-old male patient on dialysis for 7.1 years (A). Widespread fibrosis is present, and interstitial fibrosis surrounds each
myocyte (AZ stain, 400 xs). This patient died of ventricular arrythmia 1.1 years after biopsy. A 56-year-old male patient on dialysis
for 6.8 years (B). Only a little interstitial fibrosis present (AZ stain, 400 x). This patient had no cardiac events during 3.8 years of
follow-up.
Adapted from Aoki et al. Kidney International, Vol. 67 (2005), pp. 333-340
2- Imaging evidence:
By far the easiest way to study uremic changes of the myocardium in CKD patients is
echocardiography, which in studies, showed a graded relationship between the severity of
CKD and the prevalence and severity of LVH.25,30,31
Further and more precise
identification of CKD-related CVD can be demonstrated by CMR.
Mark et al. first used magnetic resonance imaging to discribed the patterns of
myocardial fibrosis in end stage renal disease patients. 5 Using late gadolinium
enhancement (LGE) as a way to detect fibrosis, they demonstrated two patterns. The first
pattern – subendocardial LGE, consistent with that described in myocardial infarction –
followed a primarily subendocardial distribution. The second pattern was characterized as
diffuse, less intense LGE reflecting diffuse myocardial fibrosis (figure 3). The latter
8
pattern was associated with greater LV mass compared with ESRD patients without LGE
(p<0.01).
Figure 3. Patterns of myocardial fibrosis in CKD on cardiac magnetic resonance imaging
(a) Short axis view of the left ventricle of hemodialysis patient demonstrating a diffuse area of gadolinium enhancement in the inferior
wall of the left ventricle (arrowed). Signal intensity of this area is 17.6 compared to the 6.9 for the LGE-negative area. (b) Short axis
view of the left ventricle of another hemodialysis patient demonstrating a diffuse area of gadolinium enhancement in the lateral wall of
the left ventricle. Signal intensity of the area of late gadolinium enhancement is 32.0 compared to 8.4 for the LGE-negative area. This
patient had normal coronary arteries at angiography performed as transplant assessment.
Adapted from Mark et al.; Kidney International (2006) 69, 1839-1845
Even though CMR is the best modality to detect myocardial fibrosis, its use is
currently restricted because of the risk of a fatal condition known as nephrogenic
systemic fibrosis with gadolinium use in patients with CKD. However, in a recent cross-
sectional study,39
43 patients with non-diabetic CKD stage 2-4 (mean GFR 50±22
ml/min/1.73m2) and 43 age- and gender-matched controls with no history of
cardiovascular disease underwent CMR imaging with T1 mapping. The patients with
CKD had higher mean native T1 times (986±37 ms) and mean extracellular volume
(28±4%) compared to controls (955±30ms and 25±3%, each p<0.05). This study
9
demonstrated that the increase in diffuse myocardial fibrosis occurred even in early
stages of CKD.39
Fibroblast growth factor in individuals with CKD
FGF-23 is a hormone secreted by osteoblasts and osteocytes and released into the
circulation.40
The effects of FGF-23 are mediated by FGF receptors (FGFRs), which are
located in the renal tubules (where FGF-23 induces urinary phosphate excretion)41
,
parathyroid gland (where FGF-23 regulates the production of parathormone [PTH]), and
the blood vessels (Figure 4). Many studies show that the coreceptor Klotho is mandatory
to induce FGF-23 specific signaling pathways.42-44
Furthermore, FGF-23 decreases dietary phosphate absorption through suppression
of circulating levels of 1, 25 dihydroxyvitamin D.45
In turn, vitamin D controls
production of FGF-23. It was shown that vitamin D3 stimulates FGF-23 generation. For
example, vitamin D receptor null mice showed undetectable FGF-23 levels.46
In addition, PTH is regulated by FGF-23, which suppresses both secretion and
gene expression of PTH. 47
However, patients with CKD have elevation of both PTH and
FGF-23, which can be explained by FGF-23 resistant status associated with uremia. It
was recently found that CKD is associated with Klotho deficiency which may explain
FGF-23 resistance.48
For example, in experimental models of CKD, there is a
downregulation of the FGF-23 receptor complex klotho-FGFR1 in the parathyroid,
resulting in resistance of the parathyroid to FGF-23.48-50
This resistance contributes to the
high levels of both PTH and FGF-23 in CKD. It was also shown that secondary
hyperparathyroidism is essential for the high levels of FGF-23 in CKD, as
10
parathyroidectomy both prevents and corrects the high FGF-23 levels of experimental
renal failure.51
Serum levels of FGF-23 increase with the decline of kidney function. These levels
can reach more than 200 times the normal levels in cases of ESRD (Figure 5).52
This rise
in FGF-23 levels occurs before changes in levels of serum phosphate, PTH, or 1, 25(OH)
2 vitamin D.
In summary, it has been observed
that FGF-23 levels increase with the decline
of kidney functioning through complex
mechanisms that include involvement of
bones, kidneys and the parathyroid gland.
Figure 4: Regulation of FGF-23
Adapted from: Larsson et al.
G Ital Nefrol 2014; 31(2)-ISSN 1724-5590
Figure 5: Expected concentration range of FGF-23 as a function of eGFR.
Adapted from: Larsson et al. G Ital Nefrol 2014; 31(2)-ISSN 1724-5590
11
The relationship between FGF-23 and all-cause and cardiovascular mortality
Increased FGF-23 levels in dialysis patients were associated with significantly
increased risk of mortality during the first year on dialysis; individuals with C-terminal
FGF-23 values above the median (1752 reference units (RU)/mL) were associated with
an odds ratio of 4.5-5.7 for mortality, compared to those with C-terminal FGF-23 <1089
RU/ml. 52
These results were confirmed even in predialysis CKD patients53
. Furthermore,
other studies also showed an association between higher levels of FGF-23 and increased
cardiovascular mortality and events.54
The role of FGF-23 in the pathogenesis of CVD in individuals with CKD
Recent studies have implied a role for FGF-23 in the pathophysiology of CKD-
mineral bone disease and in vascular calcification.55
It has been shown that FGF-23 levels
are elevated in CKD patients both on dialysis and on conservative treatment, which
showed association with increased mortality and left ventricular hypertrophy.16,52
Moreover, FGF-23 has been linked to increased arterial stiffness, endothelial dysfunction,
vascular calcification,56
and major cardiovascular events.4 Furthermore, a recent study in
animal models of renal failure showed reversal of uremic cardiomyopathy characterized
by left ventricular hypertrophy and fibrosis- with fibroblast growth factor blockade.57
Cardiac Magnetic Resonance indices of myocardial fibrosis
The myocardium is made of myocytes embedded in the myocardial interstitium,
which represents the scaffolding tissue. An expansion of this interstitium due to increased
collagen (focal and diffuse fibrosis) is the end result of many pathological processes such
as acute myocardial infarction, chronic myocardial infarction, and hypertrophic
12
cardiomyopathy.58
Expansion of the interstitium is also evident in many infiltrative
processes such as amyloidosis.59
The gold standard test to evaluate myocardial fibrosis is
histological assessment with invasive myocardial biopsy. However, the clinical utility of
this test is limited due to significant morbidity and sampling error.
Advancements in cardiac magnetic resonance (CMR) imaging have allowed for
the characterization of specific patterns of myocardial fibrosis. For example, late
gadolinium enhancement imaging (LGE) made it possible to identify focal areas of
myocardial infarction and enabled a detailed phenotypic characterization of many
nonischemic cardiomyopathies.60,61
However, the LGE technique is limited in detecting diffuse myocardial fibrosis
because it relies on qualitative detection of the signal intensity difference between fibrotic
and normal myocardial tissue. This limits the ability to detect homogeneously distributed
diffuse fibrosis, which is the main type in many forms of cardiomyopathy.62,63
The recent development of T1 mapping has allowed the quantitative assessment
of diffuse myocardial fibrosis. This technique measures the intrinsic magnetic resonance
parameter T1 of the myocardium and maps its spatial distribution (T1 mapping). The
measured differences in R1 (=1/T1) values pre- and post-gadolinium contrast allow the
quantification of the myocardial extracellular volume fraction (ECV), which has been
shown to be increased in the presence of diffuse myocardial fibrosis.64-66
T1 relaxation time of a tissue indicates how rapidly protons recover after a
radiofrequency pulse. Pre-contrast (native) T1 is affected by the water content and may
represent edema or diffuse myocardial fibrosis.67
Bull et al. studied whether non-contrast
13
CMR-T1 mapping sequence could identify myocardial fibrosis in patients with moderate
and severe aortic stenosis. They obtained biopsy samples for histologic assessment of
collagen volume fraction (CVF%) in 19 patients undergoing aortic valve replacement.
They showed a significant correlation between native T1 values and CVF% (r=0.65,
p=0.002). Higher T1 values were found in participants with severe aortic stenosis
compared to controls (972±33 ms vs. 944±16, p<0.05).67
However, this technique
embodies composite signal from both myocytes and interstitium, and it varies with the
magnetic resonance imaging field strength. Measurement of post-contrast T1 mapping
provides a value linked to the interstitium, but it is also influenced by gadolinium dose,
clearance rate, time post bolus, body composition, and hematocrit.
A newer, more accurate technique has been used recently to assess myocardial
fibrosis called ECV mapping. In this technique, ECV is measured after accounting for the
hematocrit level (ECV=100 X partition coefficient X [1-hematocrit]). The partition
coefficient is determined by the slope of the linear relationship of (1/T1myo vs. 1/T1blood).66
A novel CMR technique called Modified Look-Locker Inversion (MOLLI) recovery was
developed to allow the calculation of T1 mapping and ECV using a single breath-hold.68
This technique acquires a set of 11 source images in 17 heartbeats. It consists of 3
consecutively inversion recovery-prepared electrocardiography-synchronized Look-
Locker trains.
As mentioned above, ECV is increased in conditions characterized with diffuse
myocardial fibrosis. For example Broberg et al. found higher ECV in those with
congential heart disease compared to normal controls (31.9±5.8% versus 24.8±2%;
p<0.001). However, LGE did not account for the differences seen.64
Furthermore,
14
Ugander et al. showed the ability of ECV measurement of quantitatively characterizing
myocardial infarction (ECV infarct=51±8% vs ECV normal= 27±3%; p<0.001), atypical
diffuse fibrosis (ECV=37±6), and subtle myocardial abnormalities not clinically apparent
on LGE images.66
Recently in the Multi-Ethnic Study of Atherosclerosis, Liu et al.
showed increased ECV with older age in men. In addition, they showed a higher ECV in
females compared to males (28.1±2.8 vs. 25.8±2.9, p<0.001).7 Neilan et al.
69 studied the
distribution of ECV values in a healthy population and provided histological validation of
ECV measurements in mice. The normal range they found from studying 32 well-defined
healthy volunteers was (23 - 33%, mean 28±3%). In mice, they showed a significant
association between ECV and histological extent of fibrosis (r=0.94, p <0.001).
CMR T1 mapping was shown to correlate with myocardial fibrosis in many
different cardiac conditions such as acute myocardial infarction70
, chronic myocardial
infarction71
, acute myocarditis72
, aortic stenosis73
, hypertrophic cardiomyopathy74
,
congenital heart disease64
, idiopathic dilated cardiomyopathy, and infiltrative heart
diseae59
. These studies showed the ability of CMR-T1 mapping to detect diffuse
myocardial fibrosis, validated by histological evidence in several forms of
cardiomyopathy.
In summary, CMR imaging with T1 mapping and calculation of ECV is a novel
and validated non-invasive method to quantify the extent of diffuse myocardial fibrosis
even without the use of gadolinium. Furthermore, ECV measurement is superior to LGE
which can only give a qualitative assessment of focal areas of fibrosis.
15
FGF-23 and CMR:
Higher serum FGF-23 concentrations were associated with progressively greater
left ventricular mass and a greater prevalence of LVH. Kestenbaum et al. showed a linear
relationship between FGF-23 and left ventricular mass even after adjustment for
established LVH risk factors. For each 20-pg/mL higher serum FGF-23 concentration
there was an increase of 1.2 g in left ventricular mass (95% confidence interval, 0.2-2.2 g
greater) after full adjustment for common cardiovascular risk factors.3
Conceptual Model
Our understanding of the pathogenesis of heart failure and cardiovascular disease
among CKD patients is summarized by the conceptual model in (Figure 6). Abnormally
high levels of FGF-23 have several deleterious effects on the myocardium that ultimately
lead to heart failure. The model includes different mechanisms by which FGF-23
increases. Several changes occur with declining kidney function. While serum calcium,
and 1-25 (OH) vitamin D levels decline, PTH and phosphorus levels increase as part of
CKD-MBD. As a response to these derangements, FGF-23 increases and Klotho
decreases. Higher levels of FGF-23 are linked to a variety of clinical and pathological
conditions that lead to heart failure. Myocardial fibrosis is one of these conditions that
can be associated with higher levels of FGF-23. Furthermore, FGF-23 may lead to heart
failure with preserved ejection fraction (HFpEF) or diastolic heart failure as well as heart
failure with reduced ejection fraction (HFrEF) or systolic heart failure. Additionally,
Figure 6 lists possible confounders that may potentially lead to myocardial fibrosis as
16
well as the modifiers that can modify the relationship between FGF-23 levels and
myocardial fibrosis.
This conceptual model has several strengths, which include representation of the
current understanding of the pathophysiologic changes of CKD-MBD, and linking that to
the progression of heart failure throught FGF-23 based on a comprehensive literature
review. Also it acknowledges the complexity and the uncertainty of the current
understanding of this association between CKD and heart failure. Furthermore, it
considers the role of confounders and effect modifiers in the interactions between
antecedent, independent and dependent variables.
However, this conceptual model should also be considered with several
weaknesses, which include the inability to account for other mechanisms that interact
with FGF-23 levels, for example, dietary phosphate contents, the use of phosphate
binders or different vitamin D replacement preparations, aldosterone, estrogen, insulin
resistance and other unknown factors that may confound the proposed pathologic
mechanisms that link FGF-23 to heart failure.
17
Figure 6: Conceptual model of the role FGF-23 in the development of heart failure
Knowledge gap:
Though animal studies suggested a link between FGF-23 and myocardial
fibrosis,57
it is unknown whether this relationship is applicable to human populations.
Furthermore, the relationships between FGF-23 levels and CMR indices of myocardial
fibrosis have not been studied before. Additionally, though higher levels of FGF-23 were
shown to be associated with higher incidence of heart failure,3 it is yet to be determined
wither this relationship applies to both HFpEF and HFrEF. This work will be helpful
clinically and on a public health level by adding another tool of predicting myocardial
fibrosis and heart failure and thus allocating resources to prevention of the population at
risk at early stages.
18
Aims and Hypotheses
Primary Aim: To determine whether higher levels of fibroblast growth factor-23 (FGF-
23) are associated with indices of myocardial fibrosis detected by cardiac magnetic
resonance-T1 mapping in a multi-ethnic, middle aged community cohort free of heart
disease at baseline.
Secondary Aim: To determine whether FGF-23 is associated with heart failure with
preserved ejection fraction or with heart failure with reduced ejection fraction or both.
Predictor: baseline serum FGF-23
Outcomes: Extracellular volume fraction (ECV), pre-contrast T1 mapping, post-contrast
T1 mapping after 12 min, post-contrast T1 mapping after 25 min, ejection fraction,
incident HFpEF, incident HFrEF.
Primary Hypothesis: higher levels of FGF-23 are associated with higher levels of ECV
Secondary Hypothesis: FGF-23 levels are associated with both heart failure with
preserved ejection fraction and heart failure with reduced ejection fraction.
19
Methods:
We will address the first aim using a large cohort study of 1183 participants free
of cardiovascular diseae at baseline with FGF-23 measured at exam 1 (between 2000-
2002) and CMR T1 mapping performed at exam 5 (between 2010-2012). A subset of
these participants (n=588) had ECV calculated at exam 5. Participants with myocardial
scar (detected by visual assessment of any size using late gadolinium enhancement
imaging) were excluded. We will use multiple linear regression models to examine the
associations between FGF-23 and CMR indices of myocardial fibrosis (pre-contrast T1
mapping, 12-min and 25-min post-contrast T1 mapping and ECV %). ANOVA procedure
will be used to compare SAS driven least square means of CMR indices of fibrosis
between quartiles of FGF-23.
For the second aim we will use participants with baseline FGF-23 measured at
baseline exam 1 (n=6549) to examine the associations of FGF-23 with incident heart
failure, HFrEF and HFpEF. We will use Kaplan-Meier curves and log-rank procedure to
compare cumulative incidence of Heart failure, HFrEF and HFpEF by quartiles of FGF-
23. Cox proportional hazards regression models will be used to compute hazard ratios
using multivariate models.
20
References
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34. Kennedy DJ, Vetteth S, Periyasamy SM, et al. Central role for the cardiotonic steroid marinobufagenin in the pathogenesis of experimental uremic cardiomyopathy. Hypertension 2006;47:488-95. 35. London GM. Left ventricular alterations and end-stage renal disease. Nephrol Dial Transplant 2002;17 Suppl 1:29-36. 36. Aoki J, Ikari Y, Nakajima H, et al. Clinical and pathologic characteristics of dilated cardiomyopathy in hemodialysis patients. Kidney international 2005;67:333-40. 37. Mall G, Huther W, Schneider J, Lundin P, Ritz E. Diffuse intermyocardiocytic fibrosis in uraemic patients. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association 1990;5:39-44. 38. Mall G, Rambausek M, Neumeister A, Kollmar S, Vetterlein F, Ritz E. Myocardial interstitial fibrosis in experimental uremia--implications for cardiac compliance. Kidney international 1988;33:804-11. 39. Edwards NC, Moody WE, Yuan M, et al. Diffuse interstitial fibrosis and myocardial dysfunction in early chronic kidney disease. The American journal of cardiology 2015;115:1311-7. 40. Larsson T, Marsell R, Schipani E, et al. Transgenic mice expressing fibroblast growth factor 23 under the control of the alpha1(I) collagen promoter exhibit growth retardation, osteomalacia, and disturbed phosphate homeostasis. Endocrinology 2004;145:3087-94. 41. Gattineni J, Bates C, Twombley K, et al. FGF23 decreases renal NaPi-2a and NaPi-2c expression and induces hypophosphatemia in vivo predominantly via FGF receptor 1. American journal of physiology Renal physiology 2009;297:F282-91. 42. Dailey L, Ambrosetti D, Mansukhani A, Basilico C. Mechanisms underlying differential responses to FGF signaling. Cytokine & growth factor reviews 2005;16:233-47. 43. Kurosu H, Ogawa Y, Miyoshi M, et al. Regulation of fibroblast growth factor-23 signaling by klotho. The Journal of biological chemistry 2006;281:6120-3. 44. Razzaque MS, Lanske B. The emerging role of the fibroblast growth factor-23-klotho axis in renal regulation of phosphate homeostasis. The Journal of endocrinology 2007;194:1-10. 45. Shimada T, Hasegawa H, Yamazaki Y, et al. FGF-23 is a potent regulator of vitamin D metabolism and phosphate homeostasis. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 2004;19:429-35. 46. Shimada T, Yamazaki Y, Takahashi M, et al. Vitamin D receptor-independent FGF23 actions in regulating phosphate and vitamin D metabolism. American journal of physiology Renal physiology 2005;289:F1088-95. 47. Ben-Dov IZ, Galitzer H, Lavi-Moshayoff V, et al. The parathyroid is a target organ for FGF23 in rats. The Journal of clinical investigation 2007;117:4003-8. 48. Canalejo R, Canalejo A, Martinez-Moreno JM, et al. FGF23 fails to inhibit uremic parathyroid glands. Journal of the American Society of Nephrology : JASN 2010;21:1125-35. 49. Galitzer H, Ben-Dov IZ, Silver J, Naveh-Many T. Parathyroid cell resistance to fibroblast growth factor 23 in secondary hyperparathyroidism of chronic kidney disease. Kidney Int 2010;77:211-8. 50. Komaba H, Goto S, Fujii H, et al. Depressed expression of Klotho and FGF receptor 1 in hyperplastic parathyroid glands from uremic patients. Kidney Int 2010;77:232-8. 51. Lavi-Moshayoff V, Wasserman G, Meir T, Silver J, Naveh-Many T. PTH increases FGF23 gene expression and mediates the high-FGF23 levels of experimental kidney failure: a bone parathyroid feedback loop. Am J Physiol Renal Physiol 2010;299:F882-9.
23
52. Gutierrez OM, Mannstadt M, Isakova T, et al. Fibroblast growth factor 23 and mortality among patients undergoing hemodialysis. The New England journal of medicine 2008;359:584-92. 53. Isakova T, Xie H, Yang W, et al. Fibroblast growth factor 23 and risks of mortality and end-stage renal disease in patients with chronic kidney disease. Jama 2011;305:2432-9. 54. Kendrick J, Cheung AK, Kaufman JS, et al. FGF-23 associates with death, cardiovascular events, and initiation of chronic dialysis. Journal of the American Society of Nephrology : JASN 2011;22:1913-22. 55. Nitta K, Nagano N, Tsuchiya K. Fibroblast growth factor 23/klotho axis in chronic kidney disease. Nephron Clinical practice 2014;128:1-10. 56. Desjardins L, Liabeuf S, Renard C, et al. FGF23 is independently associated with vascular calcification but not bone mineral density in patients at various CKD stages. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA 2012;23:2017-25. 57. Di Marco GS, Reuter S, Kentrup D, et al. Treatment of established left ventricular hypertrophy with fibroblast growth factor receptor blockade in an animal model of CKD. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association 2014;29:2028-35. 58. Mewton N, Liu CY, Croisille P, Bluemke D, Lima JA. Assessment of myocardial fibrosis with cardiovascular magnetic resonance. Journal of the American College of Cardiology 2011;57:891-903. 59. Mongeon FP, Jerosch-Herold M, Coelho-Filho OR, Blankstein R, Falk RH, Kwong RY. Quantification of extracellular matrix expansion by CMR in infiltrative heart disease. JACC Cardiovascular imaging 2012;5:897-907. 60. Kim RJ, Chen EL, Lima JA, Judd RM. Myocardial Gd-DTPA kinetics determine MRI contrast enhancement and reflect the extent and severity of myocardial injury after acute reperfused infarction. Circulation 1996;94:3318-26. 61. Karamitsos TD, Francis JM, Myerson S, Selvanayagam JB, Neubauer S. The role of cardiovascular magnetic resonance imaging in heart failure. Journal of the American College of Cardiology 2009;54:1407-24. 62. de Leeuw N, Ruiter DJ, Balk AH, de Jonge N, Melchers WJ, Galama JM. Histopathologic findings in explanted heart tissue from patients with end-stage idiopathic dilated cardiomyopathy. Transplant international : official journal of the European Society for Organ Transplantation 2001;14:299-306. 63. Heymans S, Schroen B, Vermeersch P, et al. Increased cardiac expression of tissue inhibitor of metalloproteinase-1 and tissue inhibitor of metalloproteinase-2 is related to cardiac fibrosis and dysfunction in the chronic pressure-overloaded human heart. Circulation 2005;112:1136-44. 64. Broberg CS, Chugh SS, Conklin C, Sahn DJ, Jerosch-Herold M. Quantification of diffuse myocardial fibrosis and its association with myocardial dysfunction in congenital heart disease. Circulation Cardiovascular imaging 2010;3:727-34. 65. Jerosch-Herold M, Sheridan DC, Kushner JD, et al. Cardiac magnetic resonance imaging of myocardial contrast uptake and blood flow in patients affected with idiopathic or familial dilated cardiomyopathy. Am J Physiol Heart Circ Physiol 2008;295:H1234-H42. 66. Ugander M, Oki AJ, Hsu LY, et al. Extracellular volume imaging by magnetic resonance imaging provides insights into overt and sub-clinical myocardial pathology. European heart journal 2012;33:1268-78.
24
67. Bull S, White SK, Piechnik SK, et al. Human non-contrast T1 values and correlation with histology in diffuse fibrosis. Heart 2013;99:932-7. 68. Messroghli DR, Radjenovic A, Kozerke S, Higgins DM, Sivananthan MU, Ridgway JP. Modified Look-Locker inversion recovery (MOLLI) for high-resolution T1 mapping of the heart. Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine 2004;52:141-6. 69. Neilan TG, Coelho-Filho OR, Shah RV, et al. Myocardial extracellular volume fraction from T1 measurements in healthy volunteers and mice: relationship to aging and cardiac dimensions. JACC Cardiovascular imaging 2013;6:672-83. 70. Dall'Armellina E, Piechnik SK, Ferreira VM, et al. Cardiovascular magnetic resonance by non contrast T1-mapping allows assessment of severity of injury in acute myocardial infarction. Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance 2012;14:15. 71. Messroghli DR, Walters K, Plein S, et al. Myocardial T1 mapping: application to patients with acute and chronic myocardial infarction. Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine 2007;58:34-40. 72. Ferreira VM, Piechnik SK, Dall'Armellina E, et al. Non-contrast T1-mapping detects acute myocardial edema with high diagnostic accuracy: a comparison to T2-weighted cardiovascular magnetic resonance. Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance 2012;14:42. 73. Flett AS, Sado DM, Quarta G, et al. Diffuse myocardial fibrosis in severe aortic stenosis: an equilibrium contrast cardiovascular magnetic resonance study. European heart journal cardiovascular Imaging 2012;13:819-26. 74. Flett AS, Hayward MP, Ashworth MT, et al. Equilibrium contrast cardiovascular magnetic resonance for the measurement of diffuse myocardial fibrosis: preliminary validation in humans. Circulation 2010;122:138-44.
25
CHAPTER TWO: MANUSCRIPT
Fibroblast Growth Factor-23 and Cardiac-MRI Indices of
Myocardial Fibrosis in the Multi-Ethnic Study of
Atherosclerosis
Short Title: FGF-23 and CMR indices of myocardial fibrosis in MESA.
Mohamed Faher Almahmoud, MD1, Jennifer H Jordan, PhD, MS
1, Bryan Kestenbaum,
MD2, Ronit Katz, PhD
2, Bharath Amble Venkatesh, PhD
3, João A. C. Lima, MD
3,4, Chia-
Ying Liu, PHD5, Erin D. Michos, MD, M.H.S
4, David M Herrington, MD, M.H.S
1
1Department of Internal Medicine, Section on Cardiovascular medicine, Wake Forest School of
Medicine, Winston-Salem, NC, USA
2Kidney Research Institute, Department of Medicine, Division of Nephrology, University of
Washington, Seattle, WA, USA
3Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
4Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
5Radiology and Imaging Sciences, National Institutes of Health (NIH), Bethesda, MD, USA
Correspondence:
Mohamed Faher Almahmoud MD, Department of Internal Medicine, Section on Cardiology
Wake Forest School of Medicine
Medical Center Boulevard, Winston-Salem, NC
Tel: (336)716.2255, Fax: (336)716.3202
Email: [email protected]
26
Abstract
Background: Fibroblast growth factor-23 (FGF-23) is associated with myocardial
fibrosis in animal studies. We examined the associations between FGF-23 and Cardiac
Magnetic Resonance (CMR) indices of myocardial fibrosis using T1 mapping.
Methods: A total of 6547 study participants free of heart disease at baseline, had serum
FGF-23 concentrations measured between 2000-2002. We included 1183 participants
(49% Male; age 58±9 at baseline) with eGFR>45 mL/min/1.73m2 who underwent CMR
between 2010-2012 and had no evidence of focal scars on late gadolinium enhancement.
ANOVA and multivariable linear regression models were performed to determine the
relationships between baseline log2 transformed FGF-23 levels and follow up myocardial
T1 mapping (pre-contrast, 12- and 25-min post-contrast), and extracellular volume
fraction (ECV %) (n=588). Models were adjusted for cardiovascular risk factors, left
ventricular mass and stratified by gender.
Results: Overall, we found no significant relationships between FGF-23 and CMR
indices of myocardial fibrosis. However, in gender stratified, a doubling of FGF-23 was
associated with an absolute 1.2% higher ECV (95% CI: 0.33, 2.05%; p=0.007) and a
near significant 7.1(ms) higher pre-contrast myocardial T1 mapping (95% CI: -0.1, 14.4;
p=0.053) in men. Overall there was a trend for a positive relationship between FGF-23
quartiles and pre-contrast myocardial T1 mapping (p-trend =0.02). After stratification,
men in the highest quartile (FGF-23 >46.1 pg/ml) had significantly higher pre-contrast
myocardial T1 mapping and ECV values (973±3 (ms), 26.3±0.3%, respectively)
27
compared to those in the lowest quartile (FGF-23 <31 pg/ml) (961±4 (ms), 24.7±0.4%,
respectively) (p value=0.002 and 0.01 respectively). In contrast, we found no significant
association between FGF-23 and CMR indices of myocardial fibrosis in women.
Conclusion: In men FGF-23 is positively associated with CMR indices of myocardial
fibrosis. This mechanism may explain the increased risk for heart failure associated with
higher levels of FGF-23.
28
Introduction
Myocardial fibrosis is a common endpoint in a variety of cardiac diseases.1
Diffuse myocardial fibrosis occurs as a part of normal aging;2 however, this process is
accelerated in many diseases.3-5
This diffuse fibrosis is associated with worsening
ventricular function and increased ventricular stiffness, and has independent predictive
value for major cardiac events and increased all-cause mortality.6-10
The pathogenesis of
myocardial fibrosis, which leads to significant increase in collagen deposition in the
myocardium, is yet not fully understood.
Recently, fibroblast growth factor-23 (FGF-23) and its coreceptor Klotho have
been shown to be associated with myocardial fibrosis and left ventricular hypertrophy in
animal studies.11,12
FGF-23 is a hormone secreted by osteoblasts/osteoclasts. It functions
as a phosphaturic factor in the renal tubules and a regulator of parathyroid hormone, thus
regulating calcium and phosphate homeostasis. Higher serum levels of FGF-23 were
shown to be associated with variety of cardiovascular cardiac diseases.13,14
For example,
Kestenbaum et al showed that higher serum FGF-23 concentrations are associated with
incident heart failure, left ventricular hypertrophy and coronary disease events in a
population free of heart disease at baseline13
. However, it is unknown whether this
increase in incident heart failure and left ventricular hypertrophy is associated with
increased myocardial fibrosis.
The best available non-invasive method of examining myocardial fibrosis is
contrast-enhanced cardiac magnetic resonance (CMR). The use of late gadolinium
enhancement imaging (LGE) enabled the identification of focal myocardial fibrosis.15
However, this technique is limited in detecting diffuse myocardial fibrosis because it
29
depends on the signal intensity difference between fibrotic and nonfibrotic tissues which
is reduced in homogeneously distributed fibrosis.16
Recent development of T1 mapping allowed the quantitative assessment of
diffuse myocardial fibrosis through the measurement of the intrinsic magnetic resonance
relaxation parameter T1 of the myocardium.17
T1 mapping time (in milliseconds)
represents protons recovery time after radiofrequency pulse. Longer pre-contrast (native)
T1 mapping and shorter post-contrast T1 mapping were shown to be associated with
diffuse myocardial fibrosis.18,19
A newer more accurate technique allows quantification of the extracellular
volume fraction (ECV) by measuring the ratio of change in myocardial T1 relative to
blood-pool T1 pre and post-contrast after correcting for hematocrit.20
ECV is increased in
conditions characterized with diffuse myocardial fibrosis.21,22
In a large multi-ethnic cohort of men and women, we hypothesized that higher levels of
FGF-23 would be associated with indices of myocardial fibrosis.
Methods
Study population
The Multi-Ethnic Study of Atherosclerosis (MESA) is a prospective cohort study
investigating risk factors and progression of subclinical cardiovascular disease among
6814 community-living individuals. 23
Between 2000 and 2002, the MESA recruited
participants free of cardiovascular disease aged 45 to 84 years from six sites from United
States, Baltimore, MD; Chicago, IL; St. Paul, MN; Forsyth County, NC; New York, NY;
and Los Angeles, CA. The MESA recruited a final population that was 38% white, 28%
black, 22% Hispanic, and 12% Chinese-Americans. The study excluded any participants
30
with self-reported history of myocardial infarction, angina, stroke, transient ischemic
attack, heart failure, atrial fibrillation, nitroglycerin use, angioplasty, coronary artery
bypass grafting, valve replacement, pacemaker or defibrillator, or any surgery on the
heart or arteries. All participants gave informed consent, and institutional review board
approval was obtained for each site.
We evaluated all participants who had FGF-23 measurement at baseline and
subsequently had cardiac magnetic resonance (CMR) with T1 mapping (n=1183) and
ECV% measurement (n=588) on the 5th
follow-up exam (between 2010-2012). Refer to
(Figure 1) for explanation of participants’ enrollment in this study.
Study procedures: CMR imaging.
MESA participants without contraindications underwent CMR examinations by
using 1.5-T scanners (Avanto and Espree, Siemens Medical Systems, Eelangen,
Germany) with a 6-channel anterior phased array torso coil and corresponding posterior
coil elements. Left ventricular (LV) function, dimensions, and myocardial mass were
assessed by a cine steady-state free precession sequence. Twelve short axis slices, one 4-
chamber view, and one 2-chamber view were acquired. Participants undergoing CMR
scans were screened for gadolinium eligibility. The inclusion criteria were the estimated
glomerular filtration rates (eGFRs). Participants with an eGFR ≥45 ml/min (60 ml/min
for the site at Northwestern University) and with no history of allergic reaction to contrast
agents were qualified to receive gadolinium. Late gadolinium enhancement images were
obtained 15 min after an intravenous bolus injection of gadolinium-diethylene triamine
pentaacetic acid (0.15 mmol/kg [Magnevist, Bayer Healthcare Pharmaceuticals,
Montville, New Jersey]) to identify myocardial fibrosis. Twelve short-axis slices, 1
31
horizontal long axis, and 1 vertical long axis at the same positions as the LV function
cine images were acquired.
For evaluation of diffuse fibrosis, 1 short axis MOLLI image at the mid-slice
position was acquired pre-contrast (native), then repeated at 12 and 25 min post-contrast
administration. 12-and 25 min post-contrast T1 maps are used to draw the inversion
recovery curve. The timing was chosen to be comparable with previous studies and also
to accommodate the design of the entire CMR protocol.24-26
The MOLLI sequence
acquired a set of 11 source images in 17 heartbeats. It consisted of 3 consecutively
inversion recovery-prepared electrocardiography-synchronized Look-Locker trains. Each
of the 3 trains began with an inversion pulse at specific inversion time (T1= 100, 200, and
350 ms), after which multiple single shot, steady-state free precession images were
acquired in consecutive heartbeats. All images were acquired with the same trigger delay
time in end diastole. The exact scanning parameters were as follows: flip angle =35o;
repetition time=2.2 ms; echo time=1.1 ms; field of view=360 X 360 mm; matrix=192 X
183; slice thickness = 8 mm; generalized autocalibrating partially parallel acquisitions
factor=2.
We constructed T1 maps offline by using MASS research software (Department
of Radiology, Leiden University Medical Center, Leiden, The Netherland). We
performed a 3-parameter curve firt of the MOLLI source images according to the
Levenberg-Marquardt algorithm to calculate T1 values for each pixel automatically.
Then, we selected a region of interest around the core of myocardium to exclude the
blood pool and epicardial fat and calculate the myocardial T1 time for each subject. T1
maps were calculated pre-contrast (native) and 12-min, 25 min post-contrast. The
32
extracellular volume fraction (ECV [%]) was determined using the following equation
(ECV=100 X partition coefficient X [1- hematocrit]). To determine the partition
coefficient, we used the slope of the linear relationship of (1/T1 myo vs. 1/T1blood) at three
time points as described in previously published studies. 2,26-28
Because ECV calculation
depends on both T1 maps and hematocrit level at the time of CMR performance, only a
subset of the participants (n=608) with available hematocrit data at the time of CMR
examination had ECV calculated. Of them 588 with available FGF-23 data were included
in our analysis (Figure 1).
Measurement of Serum FGF-23 Concentrations
The University of Vermont Laboratory for Clinical Biochemistry stored fasting
blood and urine samples collected by MESA study personnel using established
methods.29
These samples were shipped on dry ice to the University of Washington
where serum FGF-23 concentrations were measured using the Kainos Immunoassay30
which detects the full-length biologically intact FGF-23 molecule via mid-molecule and
distal epitopes. Standarized FGF-23 controls within each run were used to monitor
quality control. The coefficient of variation across 81 plates was 6.7% and 12.4% for
high and low control samples respectively.13
Statistical Analysis
We examined the distribution of the variables and presented continuous variables
as mean ± SD and categorical variables as frequencies and percentages. Participant
characteristics were presented by FGF-23 quartiles. We used multiple linear regression
models to estimate associations of baseline serum FGF-23 concentrations and follow-up
CMR variables of myocardial fibrosis (native, 12- and 25-min post-contrast myocardial
33
T1 mapping in milliseconds (ms), and ECV %). We repeated multiple linear regression
models after dividing subjects into quartiles based on serum FGF-23 concentrations. Due
to skewed distributions, FGF-23 was explored as a continuous predictor variable after log
base 2 transformations so the parameter coefficient can be interpreted as “per doubling of
FGF-23.” Because of previous observations of gender differences in cardiac remodeling
and myocardial fibrosis,2,31
we performed the analyses overall and stratified by gender.
We performed linear regressions with multivariate adjustments for demographic variables
and risk factors. The initial model for all analyses was unadjusted. Model 2 was adjusted
for age, race, study site, highest education level completed (high school or less, some
college but no degree, college degree or more), height and weight. Model 3 was further
adjusted for systolic blood pressure (continuous), antihypertensive medications (yes
versus no), LV mass, heart rate, LDL, HDL, diabetes mellitus status (yes versus no), C-
reactive protein (CRP), smoking (current or former versus nonsmoker), urine albumin-
creatinine ratio, and eGFRCKD-Epi. P<0.05 was considered significant for all analyses
including interaction terms. All statistical analyses were performed with SAS software,
version 9.3 (SAS Institute, Cary, NC).
Because we had 2 different datasets, one with native and post-contrast T1
mapping measurements (n=1183) and a subset with ECV measurements (n=588), we had
mathematically but not clinically different cutoffs of FGF-23 quartiles. We used quartiles
cutoffs from the main dataset (n=1183) for the analyses. However, when repeating the
analysis of the association of FGF-23 with ECV based on FGF-23 quartiles specific for
the ECV dataset (n=588), we found similar results. Supplemental table 2 shows the
participant’s baseline characteristics by FGF-23 quartiles specific to the ECV dataset.
34
Results
A total of 1183 (49% men) participants with baseline FGF-23 and follow up T1
mapping free of focal scars on late gadolinium enhancement were included in the study.
Of them 588 (47% men) participants had calculated ECV values (Figure 1). Baseline
characteristics of the participants (n=1183) were presented according to quartiles of
serum FGF-23 levels (Table 1). Overall, 52.4% of the participants were white, 22%
blacks, 13.8% hispanics and 11.8% Chinese American. For the subset with calculated
ECV, 58% were white, 28% blacks and 14% hispanics. Mean eGFR was 83.8 mL/min
per 1.73 m2. There was a gradual decline in mean eGFR with increasing serum FGF-23
quartiles (P <0.001). For doubling of FGF-23, eGFR decreased by 5.67 ml/min per 1.73
m2 (95% CI 3.88, 7.47. p value <0.001). Participants in the 4
th quartile had higher body
mass index (BMI). The participant’s characteristics of the ECV dataset were presented in
supplemental table 2.
Women had significantly higher native myocardial T1 mapping and ECV and
lower 12-min and 25-min post-contrast myocardial T1 mapping compared to men (Table
2). The interaction between gender and log2FGF-23, as measured by the regression
coefficient for men and women, was near significant for native T1 mapping, and
nonsignificant for 12-min post-contrast T1 mapping and ECV (p=0.07, p=0.4 and p=0.1,
respectively) in the fully adjusted model.
Overall, there was no significant relationship between serum FGF-23 and CMR
indices of myocardial fibrosis (Table 3). However, after stratification by gender, a
doubling of FGF-23 was associated with an absolute 1.2% higher ECV (95% CI: 0.33,
35
2.05%; p=0.007) and a near significant increase in native myocardial T1 mapping by
7.1(ms) (95% CI: -0.1, 14.4 (ms); p=0.053) in men only.
When comparing adjusted mean values of CMR indices of fibrosis by quartiles of
serum FGF-23 (Figure 2), overall there was a trend for higher native myocardial T1
mapping (p-trend=0.02). After stratification by gender, men had increasing native
myocardial T1 mapping and ECV values with higher serum FGF-23 quartiles. The
adjusted mean difference in native myocardial T1 mapping for men in the 4th
quartile
compared to the 1st quartile was 12 (ms) (95% CI: 3, 21 (ms), p-trend=0.002) and an
absolute difference of 1.55% in ECV (95% CI: 0.6, 2.5%; p-trend =0.01). No statistically
significant relationship between serum FGF-23 concentration and either native
myocardial T1 mapping or ECV was seen in women.
We found no significant relationship between FGF-23 and 12-min, 25-min post-
contrast myocardial T1 mapping. We found high correlation between the two post-
contrast myocardial T1 mapping variables [r2] =0.84, thus only 12-min post-contrast
myocardial T1 mapping was presented in table (3) and figure (2).
Discussion
In the Multi-Ethnic Study of Atherosclerosis, we evaluated the relationship
between serum FGF-23 concentrations and myocardial tissue composition by using CMR
T1 mapping. Overall, we found no significant relationship between serum FGF-23
concentrations and indices of myocardial fibrosis. However, after stratification by gender,
we found a significantly positive relationship between serum FGF-23 concentration and
both native myocardial T1 mapping and extracellular volume in men. Additionally, we
36
found a significant trend between quartiles of FGF-23 and native myocardial T1 mapping
overall and in men. These findings can be interpreted as an increase in the collagen
composition of the myocardium and thus increased diffuse myocardial fibrosis. However,
we did not find statistically significant associations between serum FGF-23 concentration
and CMR indices of myocardial fibrosis in women.
Myocardial fibrosis is a pathological process observed as a response to
myocardial injury. The gold standard method to detect diffuse myocardial fibrosis is
endomyocardial biopsy.32
However, this method is invasive and is subject to sampling
error. CMR T1 mapping has been shown to provide a non-invasive validated
quantification of cardiac tissue composition and fibrosis.16
While focal fibrosis usually
follows myocardial infarction,33
diffuse myocardial fibrosis has been detected in non-
ischemic cardiomyopathy,34
hypertrophic cardiomyopathy,35
heart failure,24
diabetes,36
atrial fibrillation,37
aging,2 and infiltrative cardiomyopathies.
38 It is commonly associated
with LV hypertrophy,39
abnormal cardiac remodeling,40
and worsening ventricular
systolic and diastolic function.41,42
FGF-23 regulates calcium and phosphorus hemostasis through binding to FGF
receptors and klotho, its coreceptor in the kidney and parathyroid glands.43,44
FGF-23
concentrations increase and soluble klotho concentrations decrease in chronic kidney
disease with progressive decline of phosphorus excretion.45
Previous animal studies
suggested a causal role for FGF-23 in the development of cardiovascular disease. In
mice, intravenous injection of FGF-23 induced pathological hypertrophy of isolated
cardiomyocytes by klotho-independent mechanism.11
Administration of FGF receptors
blocker to a rat model of CKD attenuated the severity of LVH without reducing elevated
37
blood pressure.11
Furthermore, higher levels of FGF-23 concentrations were associated
to increased myocardial fibrosis and remodeling in presence of moderate or severe klotho
deficiency.46
This pathologic elevation in FGF-23 provides a key mechanism of the abnormally
high prevalence of LV hypertrophy,47
heart failure,48
and myocardial fibrosis,49
as well as
the increased cardiovascular mortality noted in patients with CKD.50,51
This is important
because FGF-23 levels start increasing at early stages of CKD (eGFR <75). In fact, it was
found that CKD was associated with increased myocardial fibrosis even at early stages.52
Our findings of differences in CMR indices of myocardial fibrosis between men
and women are consistent with previous study of age-related effect on myocardial
fibrosis by Liu et al,2 which demonstrated significantly higher ECV in women, and more
pronounced increase in ECV with age in men. Our findings of different response of the
myocardium to higher levels of FGF-23 are also consistent with previous studies of
gender differences in myocardial response to different stimuli.31
For example, while
women tend to preserve their myocardial mass, myocyte number and volume, men lose
myocardial mass and myocyte number, but increase in myocyte cell volume.53
Furthermore, in a post-mortem study, Mallat et al. showed that the apoptotic index was
found to be 3-fold higher in men compared to women free of cardiovascular disease.54
Compared to men, women have greater degree of LV hypertrophy and preserved LV
function in response to pressure overload.55
Similar findings were seen as a response to
volume overload. For example, Gardner et al. demonstrated that female rats developed
concentric hypertrophy with no impairment of cardiac function and no changes in
myocardial compliance after 8 weeks of infra-renal aortocaval fistula creation. In contrast
38
male rats developed a significant fistula-related dilation and increase ventricular
compliance.56
Thus, women may be protected from fibrosis.
We found no significant relationship between FGF-23 and 12-min, 25-min post-
contrast myocardial T1 mapping. However, measurement of post-contrast myocardial T1
mapping provides a value linked to the interstitium, but it is also influenced by
gadolinium dose, clearance rate, time post bolus, body composition, and hematocrit.
Because of these limitations, native T1 mapping and ECV measurement are preferred
over post-contrast T1 mapping for the detection of myocardial fibrosis.57
Furthermore,
ECV represent a newer, more accurate technique of myocardial fibrosis quantification
that is intended to reduce the effects of these variables by using T1 maps of the
myocardium and the blood at three time points (native, 12-and 25-min post-contrast T1
mapping) after correction for hematocrit.26
Based on our findings, we believe there are fundamental differences in the
myocardial response to higher serum FGF-23 concentrations between men and women
consistent with the differences in cardiac remodeling present in response to aging,2
pressure overload,55
volume overload,56
and myocardial infarction.58
Limitations:
ECV values were only measured for a subset of participants (n=588). Only those with
available hematocrit data at the time of CMR examination were used to calculate ECV
(Figure 1). Since only Participants with a GFR ≥45 ml/min (60 ml/min for the site at
Northwestern University) underwent ECV calculation, this subset may represent a
healthier group. Also, since different inclusion criteria were used at different sites as
39
mentioned above, this may introduce heterogeneity. To overcome this we used
multivariate regression to adjust for study site and other potential confounders. We
performed post-hoc stratification by gender. Finally, CMR with T1 mapping was
performed only once at the 5th
follow up exam 10 years after FGF-23 measurement.
Because of this time gap we recognize the potential effect of attrition which may bias our
results. For example, participants with higher FGF-23 are usually sicker and might be
less likely to follow up.
Conclusion:
In a community-based, multi-ethnic cohort free of clinical cardiovascular disease at
baseline, we observed significant associations between higher serum FGF-23
concentrations and higher native myocardial T1 mapping and ECV in men. Our findings
suggest that FGF-23 effects on the myocardium varies by gender and are likely similar to
the effects observed with cardiac remodeling noticed in aging. This mechanism may
explain the accelerated myocardial aging and the higher prevalence of heart failure
observed in patients with CKD. Further studies of FGF-23 effects on the myocardium
may further explore these gender differences.
40
Figure 1. Participant enrollment in the study
Year 2000
N=6814 enrolled in baseline exam
N=6547 had FGF-23 measured at baseline exam
Year 2010-2012
N=1183 with baseline FGF-23 and T1 mapping
N=113 excluded due to visible scar by late
gadolinium enhancement
N=1334 had T1 mapping
N=588 with baseline FGF-23 and ECV
41
Table 1. Baseline characteristics by Fibroblast Growth Factor-23 Quartile
Values are mean ±SD. SBP: Systolic blood pressure. Smoking: current and former versus never. HTN: Hypertension. GFR:
glomerular filtration rate. LVEDM: left ventricular end-diastolic mass (g).
FGF-23 Quartiles
Characteristic overall <31 31-38.2 38.2-46.1 46.1-169.9 P value
No. of subjects 1183 296 296 296 295
Age, y 58±8.7 58±8 57±9 58±9 59±9 0.2
gender 0.004
Female 603 (51%) 173 (58%) 135 (46%) 137 (46%) 158 (54%)
Male 580 (49%) 123 (42%) 161 (54%) 159 (54%) 137 (46%)
Race 0.3
White% 620 (52%) 137 (46%) 154 (52%) 158 (53%) 171 (58%)
Chinese% 140 (12%) 41 (14%) 38 (13%) 31 (11%) 30 (11%)
Black% 260 (22%) 75 (26%) 61 (21%) 64 (22%) 60 (21%)
Hispanic% 163 (14%) 43 (14%) 43 (14%) 43 (14%) 34 (12%)
Diabetes mellitus 176 (15%) 39 (13%) 37 (13%) 46 (16%) 54 (18%) 0.18
Smoking 606 (51%) 161 (54%) 158 (53%) 149 (50%) 138 (47%) 0.2
Education 0.5
High school or less% 304 (26%) 78 (27%) 75 (26%) 86 (29%) 65 (22%)
Some college% 200 (17%) 51 (17%) 45 (15%) 51 (16%) 53 (18%)
College degree or
more%
677 (57%) 165 (56%) 176 (59%) 159 (55%) 177 (60%)
Height (cm) 168±10 167±9 169±9 169±10 169±10 0.1
Weight (kg) 175±37 168±36 177±36 176±36 180±36 <0.001
Body mass index (kg/m2) 28±5 27±5 28±5 28±5 29±5 <0.001
SBP, mm Hg 122±19 122±21 120±19 122±19 123±19 0.3
HTN medication 303 (26%) 76 (26%) 67 (23%) 70 (24%) 90 (31%) 0.13
Estimated GFR,
mL/min per 1.73 m2
84±15 87±17 84±14 84±14 80±15 <0.001
LVEDM (g) 122±32 117±32 125±32 124±33 124±31 0.02
42
Table 2. CMR indices of myocardial fibrosis by gender
Variable Overall Male Female P value
NativeT1 mapping
(ms) 977±43 968±38 985±45 <0.0001
12 min post-contrast
T1 mapping (ms) 457±40 472±33 442±42 <0.0001
25 min post-contrast
T1 mapping (ms) 520±41 535±34 506±41 <0.0001
ECV% 26.9±3.0 25.8±2.8 28±2.8 <0.0001
Values are mean ±SD. ECV: extracellular volume. P value from student t test comparing CMR indices between males and females.
1183 participants had pre- and post-contrast T1 mapping, while 588 participants had ECV measured.
Table 3. Association of FGF-23 with native myocardial T1 mapping, post-contrast T1 mapping,
and extracellular volume
CMR
indices of
myocardial
fibrosis
Gender
FGF-23 Quartiles Linear Model
<31 31-38.2 38.2-46.1 >46.1
Per
doubling of
FGF-23
P value
Native
myocardial
T1 map (ms)
Overall 971±3 974±3 980±3 975±3 2.6 0.3
Men 961±4 966±3 976±3 973±4 7.1 0.053
Women 978±4 983±4 987±4 977±4 0.07 0.9
12-min post-
contrast
myocardial
T1 map (ms)
Overall 458±2 459±2 461±2 457±2 1 0.6
Men 471±3 473±3 473±3 470±3 -1.9 0.5
Women 446±3 443±3 448±3 445±3 2.5 0.4
ECV%
Overall 26.5±0.3 26.9±0.3 26.8±0.3 27±0.2 0.28 0.3
Men 24.7±0.4 25.4±0.3 25.6±0.3 26.3±0.3 1.2 0.007
Women 27.7±0.4 28.2±0.4 28±0.4 27.8±0.4 0.1 0.7
Analysis of variance procedure was used to compare SAS derived least square means of CMR-indices of myocardial fibrosis between
FGF-23 quartiles. For the linear model we used nested multivariate linear regression analysis to examine the association between log2
FGF-23 and CMR indices of myocardial fibrosis. The values are regression coefficient values. For example, for every doubling of
FGF-23 there is an absolute 1.2% increase in ECV. Values are presented as means ± SE. Models were stratified by gender and
adjusted for age, race/ethnicity, study site, education, height and weight; systolic blood pressure, antihypertensive medications, left
ventricular mass, heart rate, low density lipoprotein, high density lipoprotein, diabetes mellitus, smoking, C-reactive protein, urine
albumin-creatinine ratio and eGFRCKD-EPI. P value <0.05 is considered significant. 1183 participants had pre- and post-contrast T1
mapping, while 588 participants had ECV measured
43
Figure 2. Associations between serum FGF-23 quartiles and Native myocardial T1 mapping, 12-
min post-contrast myocardial T1 mapping and ECV, overall (green color) and stratified by
gender, male (blue color) and women (red color).
Overall Men Women
950
955
960
965
970
975
980
985
990
995
Q1 Q2 Q3 Q4
Me
an N
ativ
e T
1 m
aps
(ms)
p-trend=0.02
950
955
960
965
970
975
980
985
990
995
Q1 Q2 Q3 Q4
p-trend=0.002
950
955
960
965
970
975
980
985
990
995
Q1 Q2 Q3 Q4
p-trend=0.13
440
445
450
455
460
465
470
475
480
Q1 Q2 Q3 Q4
Me
an 1
2-m
in p
ost
-co
ntT
1 m
aps
(ms)
p-trend =0.5
440
445
450
455
460
465
470
475
480
Q1 Q2 Q3 Q4
p-trend=0.7
440
445
450
455
460
465
470
475
480
Q1 Q2 Q3 Q4
p-trend=0.8
23
24
25
26
27
28
29
Q1 Q2 Q3 Q4
Me
an E
CV
%
p-trend=0.5
23
24
25
26
27
28
29
Q1 Q2 Q3 Q4
p-trend=0.01
23
24
25
26
27
28
29
Q1 Q2 Q3 Q4
p-trend=0.7
44
SUPPLEMENTAL MATERIAL
Supplemental Table 1: Baseline participant’s characteristics by Fibroblast Growth Factor-23
Quartile for the participants with measured ECV
Values are mean ±SD. SBP: Systolic blood pressure. Smoking: current and former versus never. HTN: Hypertension. GFR:
glomerular filtration rate.
FGF-23 Quartiles
Characteristic Overall <31.8 31.8-39.1 39.1-48.2 48.2-169.9 P value
No. of subjects 588 147 147 147 147
Age, y 58±8.7 57.7±8.2 57.1±8.6 58±9 58.7±9 0.2
Gender 0.3
Female 310 (53%) 87 (59%) 75 (51%) 73 (50%) 75 (51%)
Male 278 (47%) 60 (41%) 72 (49%) 74 (50%) 72 (49%)
Race 0.5
White% 367 (62%) 85 (58%) (93) 63% (94) 64% (95) 65%
Black% 142 (24%) 41 (28%) 35 (24%) 29 (20%) 37 (25%)
Hispanic% 79 (13%) 21 (14%) 19 (13%) 24 (16%) 15 (10%)
Diabetes mellitus 93 (16%) 19 (13%) 17 (12%) 29 (20%) 28 (19%) 0.12
Smoking 320 (54%) 83 (56%) 78 (53%) 80 (54%) 79 (54%) 0.9
Education 0.7
High school or less% 151 (26%) 33 (23%) 44 (30%) 39 (26%) 35 (24%)
Some college% 110 (19%) 28 (19%) 22 (15%) 29 (20%) 31 (21%)
College degree or
more%
325 (55%) 84 (58%) 81 (55%) 79 (54%) 81 (55%)
Height (cm) 169±10 168±9 169±9 169±10 170±11 0.6
Weight (kg) 180±36 175±37 182±35 181±36 184±37 0.16
Body mass index
(kg/m2)
29±5 28±5 29±5 29±5 29±6 0.2
SBP, mm Hg 122±19 123±21 122±18 123±19 123±17 0.9
HTN medication 170 (29%) 43 (29%) 38 (26%) 39 (27%) 50 (34%) 0.4
Estimated GFR,
mL/min per 1.73 m2
82±15 86±16 82±15 80±14 79±15 <0.001
45
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35. Ellims AH, Iles LM, Ling LH, Hare JL, Kaye DM, Taylor AJ. Diffuse myocardial fibrosis in hypertrophic cardiomyopathy can be identified by cardiovascular magnetic resonance, and is associated with left ventricular diastolic dysfunction. Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance 2012;14:76. 36. Jellis C, Wright J, Kennedy D, et al. Association of imaging markers of myocardial fibrosis with metabolic and functional disturbances in early diabetic cardiomyopathy. Circulation Cardiovascular imaging 2011;4:693-702. 37. Ling LH, Kistler PM, Ellims AH, et al. Diffuse ventricular fibrosis in atrial fibrillation: noninvasive evaluation and relationships with aging and systolic dysfunction. Journal of the American College of Cardiology 2012;60:2402-8. 38. Mongeon FP, Jerosch-Herold M, Coelho-Filho OR, Blankstein R, Falk RH, Kwong RY. Quantification of extracellular matrix expansion by CMR in infiltrative heart disease. JACC Cardiovascular imaging 2012;5:897-907. 39. Rossi MA. Pathologic fibrosis and connective tissue matrix in left ventricular hypertrophy due to chronic arterial hypertension in humans. Journal of hypertension 1998;16:1031-41. 40. Dall'Armellina E, Karia N, Lindsay AC, et al. Dynamic changes of edema and late gadolinium enhancement after acute myocardial infarction and their relationship to functional recovery and salvage index. Circulation Cardiovascular imaging 2011;4:228-36. 41. Brilla CG, Janicki JS, Weber KT. Impaired diastolic function and coronary reserve in genetic hypertension. Role of interstitial fibrosis and medial thickening of intramyocardial coronary arteries. Circulation research 1991;69:107-15. 42. Chan W, Duffy SJ, White DA, et al. Acute left ventricular remodeling following myocardial infarction: coupling of regional healing with remote extracellular matrix expansion. JACC Cardiovascular imaging 2012;5:884-93. 43. Urakawa I, Yamazaki Y, Shimada T, et al. Klotho converts canonical FGF receptor into a specific receptor for FGF23. Nature 2006;444:770-4. 44. Kurosu H, Ogawa Y, Miyoshi M, et al. Regulation of fibroblast growth factor-23 signaling by klotho. The Journal of biological chemistry 2006;281:6120-3. 45. Gutierrez O, Isakova T, Rhee E, et al. Fibroblast growth factor-23 mitigates hyperphosphatemia but accentuates calcitriol deficiency in chronic kidney disease. Journal of the American Society of Nephrology : JASN 2005;16:2205-15. 46. Hu MC, Shi M, Cho HJ, et al. Klotho and phosphate are modulators of pathologic uremic cardiac remodeling. Journal of the American Society of Nephrology : JASN 2015;26:1290-302. 47. Tucker B, Fabbian F, Giles M, Thuraisingham RC, Raine AE, Baker LR. Left ventricular hypertrophy and ambulatory blood pressure monitoring in chronic renal failure. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association 1997;12:724-8. 48. Dhingra R, Gaziano JM, Djousse L. Chronic kidney disease and the risk of heart failure in men. Circulation Heart failure 2011;4:138-44. 49. Mall G, Huther W, Schneider J, Lundin P, Ritz E. Diffuse intermyocardiocytic fibrosis in uraemic patients. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association 1990;5:39-44. 50. Collins AJ, Foley RN, Chavers B, et al. US Renal Data System 2013 Annual Data Report. American journal of kidney diseases : the official journal of the National Kidney Foundation 2014;63:A7.
48
51. Go AS, Chertow GM, Fan D, McCulloch CE, Hsu CY. Chronic kidney disease and the risks of death, cardiovascular events, and hospitalization. The New England journal of medicine 2004;351:1296-305. 52. Edwards NC, Moody WE, Yuan M, et al. Diffuse interstitial fibrosis and myocardial dysfunction in early chronic kidney disease. The American journal of cardiology 2015;115:1311-7. 53. Olivetti G, Giordano G, Corradi D, et al. Gender differences and aging: effects on the human heart. Journal of the American College of Cardiology 1995;26:1068-79. 54. Mallat Z, Fornes P, Costagliola R, et al. Age and gender effects on cardiomyocyte apoptosis in the normal human heart. The journals of gerontology Series A, Biological sciences and medical sciences 2001;56:M719-23. 55. Kostkiewicz M, Tracz W, Olszowska M, Podolec P, Drop D. Left ventricular geometry and function in patients with aortic stenosis: gender differences. International journal of cardiology 1999;71:57-61. 56. Gardner JD, Brower GL, Janicki JS. Gender differences in cardiac remodeling secondary to chronic volume overload. Journal of cardiac failure 2002;8:101-7. 57. Moon JC, Messroghli DR, Kellman P, et al. Myocardial T1 mapping and extracellular volume quantification: a Society for Cardiovascular Magnetic Resonance (SCMR) and CMR Working Group of the European Society of Cardiology consensus statement. Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance 2013;15:92. 58. Biondi-Zoccai GG, Abate A, Bussani R, et al. Reduced post-infarction myocardial apoptosis in women: a clue to their different clinical course? Heart 2005;91:99-101.
49
CHAPTER THREE: ANCILLARY ANALYSES
Fibroblast Growth Factor-23 associations with Incident Heart
Failure with Reduced versus Preserved Ejection Fraction in
the Multi Ethnic Study of Atherosclerosis
Short Title: FGF-23 and HFrEF or HFpEF in MESA.
Mohamed Faher Almahmoud, MD1, Elsayed Z. Soliman MD
1, Alain G. Bertoni, MD
1,
Bryan Kestenbaum, MD2, Ronit Katz, PhD
2, João A. C. Lima, MD
3, Pamela Ouyang,
MD6, P. Elliot Miller, MD
5, Erin D. Michos, MD, M.H.S
4, David M Herrington, MD,
M.H.S1
1Department of Internal Medicine, Section on Cardiology, Wake Forest School of Medicine,
Winston-Salem, NC, USA
2Kidney Research Institute, Department of Medicine, Division of Nephrology, University of
Washington, Seattle, WA, USA
3Department of Radiology, John Hopkins University School of Medicine, Baltimore, MD, USA
4Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
5Department of Internal Medicine, Division of Hospitalist, John Hopkins University School of
Medicine, Baltimore, MD, USA
6Department of Internal Medicine, Director of women’s cardiovascular health center, John
Hopkins University School of Medicine, Baltimore, MD, USA
Correspondence:
Mohamed Faher Almahmoud MD, Department of Internal Medicine, Section on Cardiology
Wake Forest School of Medicine
Medical Center Boulevard, Winston-Salem, NC
Tel: (336)716.2255, Fax: (336)716.3202
Email: [email protected]
50
Abstract
Background: Fibroblast Growth Factor (FGF)-23 is a hormone produced by osteoblast
as a response to high serum phosphorus. High concentrations of serum FGF-23 are
associated with incident heart failure (HF) in the community. We sought to determine the
association between FGF-23 and incident heart failure with reduced (HFrEF) and with
preserved (HFpEF) ejection fraction.
Methods: We studied 6549 study participants free of heart disease at baseline enrolled in
Multi-Ethnic Study of Atherosclerosis (MESA). FGF-23 concentrations were measured at
baseline between 2000-2002 using Kainos Immunoassay. Individuals were followed for a
mean of 11.1 ± 3 years for incident HF. We classified HF events as HFrEF (ejection
fraction (EF) <50%) or HFpEF (EF ≥50%) at the time of diagnosis. We used Kaplan-
Meier curves and log-rank procedure to compare cumulative incidence of HFrEF and
HFpEF by quartiles of FGF-23. Cox proportional hazard regression was used to compute
hazard ratios (HR) and 95% confidence intervals (CI) for the association between serum
FGF-23 and incident HFrEF and HFpEF. Models were adjusted for age, gender, race,
education, study site, smoking, diabetes, systolic blood pressure, use of antihypertensive
medications, left ventricular (LV) mass, HDL-C, LDL-C, C-reactive protein (CRP),
eGFR, and log urine albumine creatinine ratio.
Results: Study participants had a total of 227 heart failure events. Of these 125 were
classified as HFrEF and 102 as HFpEF. Higher FGF-23 levels were associated with
higher risk for incident HF. For doubling of FGF-23 concentration the adjusted hazard
ratio (HR) was 1.8 (95% CI 1.3-2.5). The association between FGF-23 and HF was
51
stronger with HFpEF compared with HFrEF. Corresponding HRs were 2.6 (95% CI: 2.4-
4) for HFpEF and 1.5 (95% CI; 1-2.3) for HFrEF.
Conclusion: FGF-23 is associated with both HFpEF and HFrEF. We found a stronger
association with HFpEF in the Multi-Ethnic Study of Atherosclerosis. Our findings may
help explain the increase prevalence of HFpEF in patients with chronic kidney disease.
52
Introduction
Heart failure (HF) is a major cause of morbidity and mortality and associated high
health-care related costs.1 It is estimated to affect almost 7 million Americans.
2 Half of
these patients considered to have normal left ventricular ejection fraction (EF), and are
classified as heart failure with preserved ejection fraction (HFpEF).3 Current guidelines
define HFpEF using an EF cut-off of ≥50%.4,5
While the morbidity and mortality of heart
failure with reduced ejection fraction (HFrEF: defined as an EF<50%) is improving,6
HFpEF continues to have unchanged morbidity and mortality.7-9
Although several effective evidence based therapies are now available for the
treatment of patients with HFrEF,4 the same cannot be said about HFpEF.
10 In fact, the
exact pathophysiologic processes that lead to HFpEF are not completely understood yet.11
These processes are diverse and the condition is considered to be multifactorial and
heterogeneous.12,13
Due to this heterogeneity of HFpEF, additional research is needed to
better characterize the phenotype of HFpEF, understand the pathophysiological
processes, as well as identify the risk factors associated with this condition.
Fibroblast growth factor-23 (FGF-23), a hormone involved in phosphorus and
vitamin D hemostasis, 14-16
has been recently linked to the development of HF and left
ventricular hypertrophy (LVH).17,18
In the Mult-Ethnic Study of Atherosclerosis,
Kestenbaum et al. showed that higher serum FGF-23 concentrations are associated with
incident HF, LVH and coronary disease events19
. However, it is unknown whether this
increase in incident HF is of the preserved or reduced ejection fraction types. Even
53
though FGF-23 is strongly linked to LVH which is linked to both types of HF. FGF-23 is
also associated with several other pathologies such as arterial stiffness, endothelial
dysfunction, vascular calcifications as well as major cardiovascular events.20,21
All of
these factors can predispose to both types of HF. We hypothesize that higher levels of
FGF-23 are associated with both HFrEF and HFpEF in a Multi-Ethnic population free of
heart failure at baseline.
Methods
Study population
The Multi-Ethnic Study of Atherosclerosis (MESA) is a prospective cohort study
of cardiovascular disease among 6814 community-living individuals. 22
Between 2000
and 2002, the MESA recruited participants free of cardiovascular disease aged 45 to 84
years from six sites from United States, Baltimore, MD; Chicago, IL; St. Paul, MN;
Forsyth County, NC; New york, NY; and Los Angeles, CA. The MESA recruited a final
population that was 38% white, 28% black, 22% Hispanic, and 12% Asian. The study
excluded any participants with self-reported history of myocardial infarction, angina,
stroke, transient ischemic attack, heart failure, atrial fibrillation, nitroglycerin use,
angioplasty, coronary artery bypass grafting, valve replacement, pacemaker or
defibrillator, or any surgery on the heart or arteries. All participants gave informed
consent, and institutional review board approval was obtained for each site.
We evaluated all participants who had FGF-23 measurement at baseline with
known ejection fraction at the time of developing incident heart failure (n=6549).
54
Study procedures: CMR imaging.
MESA participants without contraindications underwent CMR examinations by
using 1.5-T scanners (Avanto and Espree, Siemens Medical Systems, Eelangen,
Germany) with a 6-channel anterior phased array torso coil and corresponding posterior
coil elements. LV function, dimensions, and myocardial mass were assessed by a cine
steady-state free precession sequence. Twelve short axis slices, one 4-chamber view, and
one 2-chamber view were acquired.
Measurement of Serum FGF-23 Concentrations
Blood and urine samples stored at the University of Vermont Laboratory for
Clinical Biochemistry were shipped on dry ice to the University of Washington where
serum FGF-23 concentrations were measured using the Kainos Immunoassay24
which
detects the full-length biologically intact FGF-23 molecule via mid-molecule and distal
epitopes. Standarized high- and low-value FGF-23 controls within each run were used to
monitor quality control.
Ascertainment of heart failure events
MESA personnel screened participants for incident events through telephone
contacts and scheduled follow up examinations. They abstracted any hospital records
suggesting cardiovascular events. They recorded symptoms, history and biomarkers;
scanned ECGs, echocardiograms, catheterization reports, outpatient records, and other
relevant diagnostic reports; and transmitted these to the coordinating center.
Two study physicians blinded to other study data independently reviewed the
medical records. Incident heart failure events were considered as probable or definite.
55
Definite or probable CHF required heart failure symptoms, such as shortness of breath or
edema, as asymptomatic disease is not a MESA endpoint. In addition to symptoms,
probable CHF required CHF diagnosed by a physician and patient receiving medical
treatment for CHF.
Definite CHF required one or more other criteria, such as pulmonary
edema/congestion by chest X-ray; dilated ventricle or poor LV function by
echocardiography or ventriculography; or evidence of left ventricular diastolic
dysfunction. We considered participants not meeting any criteria, including just a
physician diagnosis of CHF without any other evidence, as having no CHF. The Events
Committee classified heart failure as HFrEF (ejection fraction (EF) <50%) or HFpEF
(EF≥50%) at the time of heart failure diagnosis.
Statistical Analysis
We examined the distribution of the variables and presented continuous variables
as mean ± SD and categorical variables as frequencies and percentages. Basic
characteristics were presented by FGF-23 quartiles. Due to skewed distributions FGF23
was explored as a continuous predictor variable after log base 2 transformations so the
parameter coefficient can be interpreted as “per doubling of FGF23”. We used Kaplan-
Meier curves and the log-rank procedure to compare cumulative incidence of HFrEF and
HFpEF by quartiles of FGF-23. Cox proportional hazard regression was used to compute
cause-specific hazard ratios (HR) and 95% confidence intervals (CI) for the association
between log base 2 transformed FGF-23 and incident HFrEF and HFpEF first, then
between quartiles of FGF-23 and incident HFrEF and HFpEF separately. The initial
56
model was unadjusted. Model 2 was adjusted for age, race, highest education level
completed (high school or less, some college but no degree, college degree or more),
study site and body mass index (BMI). Model 3 was further adjusted for systolic blood
pressure (continuous), antihypertensive medications (yes versus no), LV mass, heart rate,
Low Density Lipoprotein (LDL), High Density Lipoprotein (HDL), diabetes mellitus
status (yes versus no), C-reactive protein (CRP), smoking (Current versus former and
never), urine albumin-creatinine ratio, and eGFRCKD-Epi. P<0.05 was considered
significant for all analyses including interaction terms. All statistical analyses were
performed with SAS software, version 9.3 (SAS Institute, Cary, NC). We tested for the
proportional hazards assumption that the effect of an explanatory variable on the hazard
is constant in time using SAS and we found no evidence of departure from this
assumption.
Results:
Among the 6549 participants (mean age 62±5.5 years), there were 53% women,
39% white, 12% Chinese, 27% black and 22% hispanics. The mean FGF-23 was 40±15
pg/ml. The mean eGFR was 81±18 mL/min/1.73m2.
Compared to participants in the lowest FGF-23 quartile (<31 pg/ml), those in the
highest quartile were older, had higher BMI, systolic blood pressure, lower eGFR, and
more likely to be diabetic (Table 1).
During a mean follow up of 11.1±3 years and a median follow up of 12.1(IQR:
11.6-12.7) years, 227 participants had incident heart failure events. Among these, 125
were classified as HFrEF and 102 were classified as HFpEF. When divided by FGF-23
57
quartiles, Q1 participants had 16 HFrEF and 16 HFpEF events, Q2 participants had 30
HFrEF and 18 HFpEF events, Q3 participants had 37 HFrEF and 24 HFpEF events, and
Q4 had 42 HFrEF and 44 HFpEF events.
We found that higher FGF-23 levels are significantly predictive of future HF
events. In adjusted models, there was an estimated 26% higher risk of HF for every 20
pg/mL increase in FGF-23 (HR 1.26; 95% CI, 1.1-1.5, p value=0.003). Each doubling of
FGF-23 levels was associated with 80% higher risk of incident HF (HR 1.8; 95% CI: 1.3-
2.5, p value <0.001) (Table 2A). We found stronger associations between higher FGF-23
levels and HFpEF events (HR 2.4; 95% CI: 1.4-4, p value <0.001) compared to HFrEF
events (HR 1.5; 95 CI 1-2.3, p value =0.06) for each doubling of FGF-23.
When comparing quartiles of FGF-23, there was a graded significant increase of
the risk of incident HF, incident HFrEF and incident HFpEF. Participants in the highest
FGF-23 quartile had higher risk of HF (HR 2.6; 95%CI; 1.5-4.7), HFrEF (HR 2.3; 95%
CI 1-5), and HFpEF (HR 2.9; 95% CI: 1.2-7.1) compared to participants in the lowest
quartile (reference) (Table 2B, Figure 1). We presented Kaplan-Meier curves with 95%
Hall-Wellner Bands and log-rank test for each outcome in Figure 2, Figure 3A and Figure
3B.
Compared to women, men had -statistically but not clinically significant- higher
FGF-23 concentration (mean FGF-23=40.6 in men compared to 39.6 in women). Because
of the observed difference we repeated the analysis with gender specific FGF-23 quartiles
with minimal cutpoints changes. However, the results were similar.
58
As we found differences between men and women in myocardial response to
higher levels of FGF-23 (in the previous chapter), we repeated the analysis after
stratification by gender. Men had 134 incident HF events with an estimated 60% higher
risk with doubling FGF-23 levels (HR 1.6; 95%CI: 1, 2.5, p value=0.05). In men, we
found significant associations between FGF-23 and each HF types in unadjusted models;
however these associations became non-significant in fully adjusted models. Women had
93 total heart failure events with stronger associations between FGF-23 levels and
incident HF (HR 2.7; 95% CI: 1.5-4.7, p value <0.001) compared to men(supplemental
Table 1). This association was especially stronger for HFpEF (HR 5.2; 95% CI: 2.4-11.7,
p value<0.001).
In sensitivity analyses we performed the analyses without adjusting for LV mass
(Supplemental Table 2A), and again after adjusting for LVH detected by
electrocardiogram (LVH-ECG) instead of LV mass (Supplemental Table 2B) and found
similar results. In additional sensitivity analyses, we adjusted for 24-hour urine phospate
excretion, serum calcium level, serum 1-25 hydroxy vitamin D level, and serum
Parathyroid hormone level and had similar findings.
Discussion:
In a middle-aged multi-ethnic population free of cardiovascular diseae at baseline
(MESA), we demonstrated that higher levels of FGF-23 were associated with higher
incidence of both HFrEF and HFpEF. We also confirmed a previous study done with the
same population but with smaller number of events (n=183) due to less follow up time,
which demonstrated an estimated 19% greater risk of incident HF with each 20 pg/mL
59
increase in FGF-23 (HR 1.19; 95% CI, 1.03-1.37).19
We found similar results. In our
linear model there was an estimated 80% higher risk of incident heart failure with
doubling of FGF-23 levels (Table 2A), and an estimated 26% higher risk for every 20
pg/mL increase in FGF-23 (HR 1.26;95% CI, 1.1-1.5, p value=0.003).
When comparing quartiles we found a graded increase in the risk of all types of
HF. Participants in the highest quartile had at least double the risk of developing HFrEF
and almost 3 times the risk of HFpEF.
We believe the findings of a strong association between FGF-23 with HF can be
explained by the previous observations that found a strong association between FGF-23
with higher LV mass.18,19
However, the reasons why we found stronger associations
between FGF-23 and HFpEF are uncertain. Several previous reports demonstrated that
higher LV mass is associated with greater risk of HF events.24-26
In a study by Velagaleti
et al, eccentric LVH was associated with higher risk of HFrEF, while concentric LVH
was associated with higher risk of HFpEF.24
Furthermore, Seliger et al, demonstrated that
LVH was associated with higher risk of both types of HF especially HFrEF. Although we
adjusted for LV mass in our fully adjusted model, other pathological mechanisms such as
myocardial fibrosis (as we demonstrated in the previous chapter) should be recognize as
another potential step that lead to the development of both HF types.
When comparing risk of heart failure by gender, we found high association
between FGF-23 levels and risk of incident HF in both men and women. The risk for
incident HF was stronger in women than in men. In women, the higher risk of HF was
especially because of strong association with HFpEF. However, our results were limited
60
with wide confidence intervals in these strata because of small number of events. Further
studies are needed to make more accurate conclusions.
To our knowledge this is the first study comparing the associations of FGF-23
with HFrEF and HFpEF. Previous studies examined the association between FGF-23
with ejection fraction as a continuous variable. For example, Kestenbaum et al, found no
significant relationship between FGF-23 and ejection fraction.19
In previous community
based studies, FGF-23 was associated with reduced ejection fraction.21,27
However, these
studies were in participants with chronic kidney disease,21
and in a population undergoing
elective coronary angiography.27
Both of these populations have sicker patients with
more cardiovascular risk factors.
Based on our findings we believe that higher levels of baseline FGF-23 are more
predictive of future HFpEF events. This is important because a significant proportion of
patients with chronic kidney disease suffer from HF especially HFpEF. For example,
50% of ESRD patients have heart failure and up to 85% have abnormal left ventricular
structure and function.28
Since patients with CKD have increasing FGF-23 levels even at
early stages,29,30
it is important to estimate the risk and understand the underlying
mechanism in order to develop new preventive and therapeutic techniques.
Furthermore, our findings of gender differences in the risk of incidence HF with
higher levels of FGF-23 confirm our previous observations of different gender-related
myocardial reaction to higher FGF-23 levels.
61
Limitations:
We only included participants with known EF at the time of HF diagnosis, thus it is
unknown whether the relationship would change had we known the EF of these
participants. Also we are limited by a small number of events to compare both types of
HF so we used definite and probable events which could lead to misclassification error.
However, even with close number of events the association was stronger for HFpEF. We
adjusted for left ventricular mass in our fully adjusted models. This adjustment led to
significant reduction in sample size and loss of power with wider confidence intervals.
However, we found similar results when adjusting for LVH detected by ECG (available
for majority of participants). Nevertheless, left ventricular hypertrophy could be a
mediator and a pathologic mechanism by which higher levels of FGF-23 lead to heart
failure.18
Finally, because of the complexity of FGF-23 physiology, residual confounding
cannot be excluded. For example, we did not adjust for 24-hour urine phosphate
excretion, serum calcium level, vitamin D level, or parathyroid hormone. However, in
sensitivity analyses, adjusting for these covariates didn’t change our results.
Conclusion:
In the Multi-Ethnic Study of Atherosclerosis, higher levels of FGF-23 were associated
with increased risk of incident HFrEF and HFpEF. We observed stronger association
with HFpEF. When comparing the risk of HF by gender, women had stronger risk for
HF, especially HFpEF.
62
Table 1. Baseline Characteristics by Fibroblast Growth Factor-23 1quartile
Values are mean ±SD. SBP: Systolic blood pressure. Smoking: current and former versus never. HTN: Hypertension. GFR: glomerular filtration rate. LV mass: left ventricular mass.
FGF-23 Quartiles
Characteristic overall <31 31-38 38-46 >46 P value
No. of subjects 6549 1639 1638 1635 1637
Age, y 62±10 61±10 62±10 62±10 64±10 <0.001
Gender <0.001
Female 3487(53%) 959(58%) 851(52%) 851(52%) 824(50%)
Male 3062(47%) 680(42%) 784(48%) 784(48%) 813(50%)
Race <0.001
White% 2544(39%) 527(32%) 620(38%) 656(40%) 741(45%)
Chinese% 794(12%) 191(12%) 214(13%) 194(12%) 195(12%)
Black% 1779(27%) 486(30%) 448(27%) 430(26%) 415(25%)
Hispanic% 1432(22%) 435(26%) 356(22%) 355(22%) 286(18%)
Diabetes mellitus 811 (12%) 203(12%) 202(12%) 175(11%) 231(14%) 0.03
Current smoking 843(13%) 274(17%) 218 (13%) 200(12%) 151(9%) <0.001
Education 0.004
High school or less% 2348(36%) 632(39%) 597(36%) 594(37%) 525(32%)
Some college% 1063(16%) 268(16%) 245(15%) 260(16%) 290(18%)
College degree or
more%
3116(48%) 732(45%) 792(49%) 774(47%) 818(50%)
Body mass index
(kg/m2)
28±5.5 27.8±5.4 27.9±5.2 28.5±5.4 29±5.6 <0.001
SBP, mm Hg 126±22 125±22 125±21 126±21 129±22 <0.001
HTN medication 2403(37%) 511(31%) 537(33%) 582(36%) 773(47%) <0.001
Estimated GFR,
mL/min per 1.73 m2
81±18 87±17 83±20 81±17 75±18 <0.001
LV mass (g) 120±29 116±28 120±29 121±30 124±31 <0.001
63
Table 2A. Associations of FGF-23 and incident heart failure, HFrEF and HFpEF
Incident
heart
failure
events
Hazard ratio
(95% CI)
P
value
Incident
HFrEF
events
Hazard ratio
(95% CI)
P
value
Incident
HFpEF
events
Hazard ratio
(95% CI)
P value
Model 1 227 2.1
(1.6-2.7)
<0.001 125 1.8
(1.3-2.5)
0.001 102 2.6
(1.8-3.7)
<0.001
Model 2 226 1.7
(1.3-2.2)
<0.001 124 1.5
(1-2)
0.04 102 2
(1.4-2.9)
<0.001
Model 3 138 1.8
(1.3-2.5)
<0.001 84 1.5
(1-2.3)
0.06 54 2.4
(1.4-4)
0.001
Cox proportional models were used to calculate the hazards ratios of each unit increase in log2 FGF-23 for the development of incident
heart failure, HFrEF and HFpEF. Log2 FGF-23 is interpreted as doubling of FGF-23. For example, for each doubling of FGF-23 there is an increase of 2.4 of the risk of HFpEF. Model 1; unadjusted, Model 2; adjusted for age, gender, race/ethnicity, education, study
site and BMI, Model 3 adjusted for model 2 and systolic blood pressure, antihypertensive medications, LV mass, heart rate, low
density lipoprotein, high density lipoprotein, diabetes mellitus, smoking, C-reactive protein, urine albumin-creatinine ratio and eGFRCKD-EPI. P value <0.05 is considered significant.
Table 2B. Association of FGF-23 and incident heart failure, HFrEF and HFpEF
(Hazards ratios per FGF-23 quartiles)
Fibroblast Growth Factor-23 Quartiles
Q1 Q2 Q3 Q4
Incident heart failure
Model 1 1.0(ref) 1.5(0.96-2.4) 1.9(1.2-2.9) 2.7(1.8-4.1)
Model 2 1.0(ref) 1.3(0.9-2.1) 1.5(1-2.4) 1.9(1.3-2.9)
Model 3 1.0(ref) 1.8(1-3.3) 2.1(1.2-3.8) 2.6(1.5-4.7)
Incident HFrEF
Model 1 1.0(ref) 1.9(1-3.4) 2.2(1.2-4) 2.7(1.5-4.8)
Model 2 1.0(ref) 1.7(0.9-3.1) 1.9(1-3.4) 2(1.2-3.6)
Model 3 1.0(ref) 2(0.9-4.4) 2.8(1.3-5.9) 2.3(1-5)
Incident HFpEF
Model 1 1.0(ref) 1.1(0.6-2.2) 1.5(0.8-2.8) 2.8(1.6-5)
Model 2 1.0(ref) 1(0.5-2) 1.1(0.6-2.2) 1.8(1-3.3)
Model 3 1.0 (ref) 1.6(0.6-4.1) 1.3 (0.5-3.3) 2.9 (1.2-7.1)
Cox proportional model was used to calculate the hazards ratios. Values presented are hazards ratios and (95% confidence intervals)
for each quartile of FGF-23 compared to reference group(Q1). Model 1; unadjusted, Model 2; adjusted for age, gender, race/ethnicity, education, study site and BMI, Model 3 adjusted for model 2 and systolic blood pressure, antihypertensive medications, LV mass,
heart rate, low density lipoprotein, high density lipoprotein, diabetes mellitus, smoking, C-reactive protein, urine albumin-creatinine
ratio and eGFRCKD-EPI. P value <0.05 is considered significant.
64
Figure 1. Hazard ratios of the associations of FGF-23 quartiles with incident heart failure, HFrEF
and HFpEF
Figure 2. Higher FGF-23 levels are associated with increased risk of incident heart failure.
Participants were stratified into quartiles of FGF-23. (Kaplan-Meier curve with 95% Hall-Wellner
Brands and log-rank test). Notice the Y axis start from 90% survival, X axis is the time to heart
failure event (days).
0
0.5
1
1.5
2
2.5
3
3.5
q1 q2 q3 q4
Haz
arad
rat
io p
er
FGF-
23
qu
arti
les
Incident Heart Failure
0
0.5
1
1.5
2
2.5
3
3.5
q1 q2 q3 q4
Incident HFrEF
0
0.5
1
1.5
2
2.5
3
3.5
q1 q2 q3 q4
Incident HFpEF
65
Figure 3A. Higher FGF-23 levels are associated with increased risk of incident HFrEF.
Participants were stratified into quartiles of FGF-23. (Kaplan-Meier curve with 95% Hall-Wellner
Bands and log-rank test).
Figure 3B. Higher FGF-23 levels are associated with increased risk of incident HFpEF.
Participants were stratified into quartiles of FGF-23. (Kaplan-Meier curve with 95% Hall-Wellner
Bands and log-rank test).
66
SUPPLEMENTAL MATERIAL
Supplemental Table 1. Associations of FGF-23 and incident heart failure, HFrEF and HFpEF
stratified by gender
Incident
heart
failure
events
Hazard
ratio (95%
CI)
P value Incident
HFrEF
events
Hazard
ratio (95%
CI)
P value Incident
HFpEF
events
Hazard
ratio (95%
CI)
P value
Men
Model 1 134 1.9
(1.4-2.7)
<0.001 86 1.8
(1.1-2.7)
0.01 48 2.3
(1.3-4)
0.004
Model 2 133 1.6
(1.1-2.2)
0.008 85 1.5
(1-2.3)
0.054 48 1.8
(1-3.2)
0.056
Model 3 86 1.6
(1-2.5)
0.05 59 1.6
(0.9-2.7)
0.1 27 1.7
(0.7-3.9)
0.2
Women
Model 1 93 2.3
(1.6-3.2)
<0.001 39 1.7
(0.9-3)
0.09 54 2.8
(1.8-4.4)
<0.001
Model 2 93 1.8
(1.2-2.6)
<0.001 39 1.3
(0.7-2.5)
0.4 54 2.2
(1.3-3.7)
0.003
Model 3 52 2.7
(1.5-4.7)
<0.001 25 1.7
(0.7-4.2)
0.24 27 5.2
(2.4-11.7)
<0.001
Cox proportional models were used to calculate the hazards ratios of each unit increase in log2 FGF-23 for the development of incident
heart failure, HFrEF and HFpEF. Log2 FGF-23 is interpreted as doubling of FGF-23. For example, for each doubling of FGF-23 there
is an increase of 5.2 of the risk of HFpEF in women. Model 1; unadjusted, Model 2; adjusted for age, race/ethnicity, education, study site and BMI, Model 3 adjusted for model 2 and systolic blood pressure, antihypertensive medications, LV mass, heart rate, low
density lipoprotein, high density lipoprotein, diabetes mellitus, smoking, C-reactive protein, urine albumin-creatinine ratio and
eGFRCKD-EPI. P value <0.05 is considered significant.
Supplemental Table 2A. Associations of FGF-23 and incident heart failure, HFrEF and HFpEF
overall and stratified by gender without adjustment for LV mass
Model 3 Incident
heart
failure
events
Hazard
ratio (95%
CI)
P value Incident
HFrEF
events
Hazard
ratio (95%
CI)
P value Incident
HFpEF
events
Hazard
ratio (95%
CI)
P value
Overall 217 1.6
(1.2-2.1)
<0.001 121 1.3
(0.9-1.9)
0.13 96 2.1
(1.4-3.1)
<0.001
Men 129 1.5
(1-2.1)
0.03 82 1.5
(0.8-2.3)
0.11 47 1.5
(0.8-2.8)
0.17
Women 88 1.9
(1.3-3)
0.003 39 1.2
(0.6-2.2)
0.7 49 2.9
(1.6-5.3)
<0.001
Cox proportional models were used to calculate the hazards ratios of each unit increase in log2 FGF-23 for the development of incident
heart failure, HFrEF and HFpEF. Log2 FGF-23 is interpreted as doubling of FGF-23. For example, for each doubling of FGF-23 there
is an increase of 2.9 of the risk of HFpEF in women. Model 3 adjusted for age, race/ethnicity, education, study site, BMI, systolic
blood pressure, antihypertensive medications, heart rate, low density lipoprotein, high density lipoprotein, diabetes mellitus, smoking,
C-reactive protein, urine albumin-creatinine ratio and eGFRCKD-EPI. P value <0.05 is considered significant.
67
Supplemental Table 2B. Associations of FGF-23 and incident heart failure, HFrEF and HFpEF
overall and stratified by gender with adjustment for LVH-ECG
Model 3 Incident
heart
failure
events
Hazard
ratio (95%
CI)
P value Incident
HFrEF
events
Hazard
ratio (95%
CI)
P value Incident
HFpEF
events
Hazard
ratio (95%
CI)
P value
Overall 217 1.6
(1.2-2.1)
<0.001 121 1.3
(0.9-1.8)
0.17 96 2.1
(1.4-3.1)
<0.001
Men 129 1.5
(1-2.1)
0.045 82 1.4
(0.9-2.2)
0.13 47 1.5
(0.8-2.8)
0.19
Women 88 1.9
(1.3-3)
0.003 39 1.1
(0.6-2.2)
0.7 49 2.9
(1.6-5.2)
<0.001
Cox proportional models were used to calculate the hazards ratios of each unit increase in log2 FGF-23 for the development of incident heart failure, HFrEF and HFpEF. Log2 FGF-23 is interpreted as doubling of FGF-23. For example, for each doubling of FGF-23 there
is an increase of 2.9 of the risk of HFpEF in women. Model 3 adjusted for age, race/ethnicity, education, study site, BMI, systolic
blood pressure, antihypertensive medications, heart rate, LVH-ECG (left ventricular hypertrophy detected by electrocardiogram), low
density lipoprotein, high density lipoprotein, diabetes mellitus, smoking, C-reactive protein, urine albumin-creatinine ratio and
eGFRCKD-EPI. P value <0.05 is considered significant.
68
1. Schocken DD, Benjamin EJ, Fonarow GC, et al. Prevention of heart failure: a scientific statement from the American Heart Association Councils on Epidemiology and Prevention, Clinical Cardiology, Cardiovascular Nursing, and High Blood Pressure Research; Quality of Care and Outcomes Research Interdisciplinary Working Group; and Functional Genomics and Translational Biology Interdisciplinary Working Group. Circulation 2008;117:2544-65. 2. Roger VL, Go AS, Lloyd-Jones DM, et al. Heart disease and stroke statistics--2012 update: a report from the American Heart Association. Circulation 2012;125:e2-e220. 3. Steinberg BA, Zhao X, Heidenreich PA, et al. Trends in patients hospitalized with heart failure and preserved left ventricular ejection fraction: prevalence, therapies, and outcomes. Circulation 2012;126:65-75. 4. McMurray JJ, Adamopoulos S, Anker SD, et al. ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 2012: The Task Force for the Diagnosis and Treatment of Acute and Chronic Heart Failure 2012 of the European Society of Cardiology. Developed in collaboration with the Heart Failure Association (HFA) of the ESC. European journal of heart failure 2012;14:803-69. 5. Yancy CW, Jessup M, Bozkurt B, et al. 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Journal of the American College of Cardiology 2013;62:e147-239. 6. Loh JC, Creaser J, Rourke DA, et al. Temporal trends in treatment and outcomes for advanced heart failure with reduced ejection fraction from 1993-2010: findings from a university referral center. Circulation Heart failure 2013;6:411-9. 7. Chan MM, Lam CS. How do patients with heart failure with preserved ejection fraction die? European journal of heart failure 2013;15:604-13. 8. Owan TE, Hodge DO, Herges RM, Jacobsen SJ, Roger VL, Redfield MM. Secular trends in renal dysfunction and outcomes in hospitalized heart failure patients. Journal of cardiac failure 2006;12:257-62. 9. Yancy CW, Lopatin M, Stevenson LW, et al. Clinical presentation, management, and in-hospital outcomes of patients admitted with acute decompensated heart failure with preserved systolic function: a report from the Acute Decompensated Heart Failure National Registry (ADHERE) Database. Journal of the American College of Cardiology 2006;47:76-84. 10. Shah AM, Pfeffer MA. The many faces of heart failure with preserved ejection fraction. Nature reviews Cardiology 2012;9:555-6. 11. Oktay AA, Rich JD, Shah SJ. The emerging epidemic of heart failure with preserved ejection fraction. Curr Heart Fail Rep 2013;10:401-10. 12. Bhuiyan T, Maurer MS. Heart Failure with Preserved Ejection Fraction: Persistent Diagnosis, Therapeutic Enigma. Current cardiovascular risk reports 2011;5:440-9. 13. Cleland JG, Pellicori P. Defining diastolic heart failure and identifying effective therapies. Jama 2013;309:825-6. 14. Larsson T, Marsell R, Schipani E, et al. Transgenic mice expressing fibroblast growth factor 23 under the control of the alpha1(I) collagen promoter exhibit growth retardation, osteomalacia, and disturbed phosphate homeostasis. Endocrinology 2004;145:3087-94. 15. Gattineni J, Baum M. Regulation of phosphate transport by fibroblast growth factor 23 (FGF23): implications for disorders of phosphate metabolism. Pediatric nephrology 2010;25:591-601. 16. Shimada T, Hasegawa H, Yamazaki Y, et al. FGF-23 is a potent regulator of vitamin D metabolism and phosphate homeostasis. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 2004;19:429-35.
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17. Ix JH, Katz R, Kestenbaum BR, et al. Fibroblast growth factor-23 and death, heart failure, and cardiovascular events in community-living individuals: CHS (Cardiovascular Health Study). Journal of the American College of Cardiology 2012;60:200-7. 18. Faul C, Amaral AP, Oskouei B, et al. FGF23 induces left ventricular hypertrophy. The Journal of clinical investigation 2011;121:4393-408. 19. Kestenbaum B, Sachs MC, Hoofnagle AN, et al. Fibroblast growth factor-23 and cardiovascular disease in the general population: the Multi-Ethnic Study of Atherosclerosis. Circulation Heart failure 2014;7:409-17. 20. Desjardins L, Liabeuf S, Renard C, et al. FGF23 is independently associated with vascular calcification but not bone mineral density in patients at various CKD stages. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA 2012;23:2017-25. 21. Scialla JJ, Xie H, Rahman M, et al. Fibroblast growth factor-23 and cardiovascular events in CKD. Journal of the American Society of Nephrology : JASN 2014;25:349-60. 22. Bild DE, Bluemke DA, Burke GL, et al. Multi-ethnic study of atherosclerosis: objectives and design. Am J Epidemiol 2002;156:871-81. 23. Imel EA, Peacock M, Pitukcheewanont P, et al. Sensitivity of fibroblast growth factor 23 measurements in tumor-induced osteomalacia. The Journal of clinical endocrinology and metabolism 2006;91:2055-61. 24. Velagaleti RS, Gona P, Pencina MJ, et al. Left ventricular hypertrophy patterns and incidence of heart failure with preserved versus reduced ejection fraction. The American journal of cardiology 2014;113:117-22. 25. Bluemke DA, Kronmal RA, Lima JA, et al. The relationship of left ventricular mass and geometry to incident cardiovascular events: the MESA (Multi-Ethnic Study of Atherosclerosis) study. Journal of the American College of Cardiology 2008;52:2148-55. 26. Seliger SL, de Lemos J, Neeland IJ, et al. Older Adults, "Malignant" Left Ventricular Hypertrophy, and Associated Cardiac-Specific Biomarker Phenotypes to Identify the Differential Risk of New-Onset Reduced Versus Preserved Ejection Fraction Heart Failure: CHS (Cardiovascular Health Study). JACC Heart failure 2015;3:445-55. 27. Seiler S, Cremers B, Rebling NM, et al. The phosphatonin fibroblast growth factor 23 links calcium-phosphate metabolism with left-ventricular dysfunction and atrial fibrillation. European heart journal 2011;32:2688-96. 28. Foley RN, Parfrey PS, Sarnak MJ. Epidemiology of cardiovascular disease in chronic renal disease. Journal of the American Society of Nephrology : JASN 1998;9:S16-23. 29. Gutierrez OM, Mannstadt M, Isakova T, et al. Fibroblast growth factor 23 and mortality among patients undergoing hemodialysis. The New England journal of medicine 2008;359:584-92. 30. Isakova T, Wahl P, Vargas GS, et al. Fibroblast growth factor 23 is elevated before parathyroid hormone and phosphate in chronic kidney disease. Kidney international 2011;79:1370-8.
70
CURRICULUM VITAE
Date Prepared: 04/01/2016
Name: Mohamed Faher Almahmoud
Office Address:
Medical Center Boulevard
Section on Hospital Medicine
Winston Salem, NC 27157-1021
Home Address:
6164 Chamberlain PL, Apt 301
Winston Salem, NC 27103
Work Phone: 336.716.2255
Cell Phone: 201-310-8484
Work Email:
Work FAX: 336.716.3202
Place of Birth: Aleppo, Syria
Education
2010 M.D. Medicine University of Aleppo
2014 Residency, Internal Medicine at St. John Hospital/Wayne State University
Professional Societies
2015
2015
2003
American Heart Association
American College of Cardiology
Syrian students union organization
Member
Member
Member
2010 Syrian Ministry of Physicians Member
2011 American College of Physicians Member
71
Honors and Prizes
2013 Poster Presentation
award
American College of
Physicians
2nd
place poster
presentation at the
associate day conference
of ACP-Michigan chapter
2014 Outstanding Resident Research Award, St. John Hospital Medical Center
Report of Local Teaching and Training
Teaching of Students in Courses
2011-2013 Instructor of Internal Medicine Wayne State University Hospital
2014-2015
2014-2016
Instructor of Internal Medicine
Cardiovascular research
fellowship
Wake Forest Baptist Medical Center
Wake Forest University
Report of Regional, National and International Invited
Teaching and Presentations
Invited Presentations and Courses
Regional
2012 Propionibacterium acne cerebral abscess following craniotomy
Almahmoud, Mohamed Faher., Anilrudh, Venugopal., Leonard, Johnson.
Oral presentation at the American College of Physicians-Michigan
chapter associate meeting
2012 Outcomes of correcting hyponatremia in patients with myocardial
infarction
Almahmoud, Mohamed Faher., Qureshi, Waqas., Alirhayim, Zaid.,
Khalid, Fatima
Research presentation at Michigan state medical society annual scientific
meeting
2013 H1N1-induced encephalitis in an adult patient
Almahmoud, Mohamed Faher., Obeid, Karam., Johnson, Leonard.
Poster presentation at the American College of Physicians-Michigan
associate meeting
2013 Isolated Mycobacterium kansasii Cellulitis and Osteomyelitis in an
Immunocompetent Patient
Almahmoud, Mohamed Faher., Obeid, Karam., Johnson, Leonard.
Poster presentation at the American College of Physicians-Michigan
associate meeting
72
2013 Seizure induced stress cardiomyopathy in an epileptic patient
Almahmoud, Mohamed Faher., Qaqish, Nicole., Michael, Frederick.
Poster presentation at the American College of Physicians-Michigan
chapter annual scientific meeting
2013
2014
2014
2014
2014
Failure Rates After Arteriovenous Fistula Creations
Ali, Sajid., Almahmoud, Mohamed Faher., Bellovic, Keith.
Poster abstract presentation at the American College of Physicians-
Michigan chapter annual scientific meeting
Outcomes of Laser-Assisted Balloon Angioplasty versus Balloon
Angioplasty Alone for Below Knee Peripheral Arterial Disease
Piyaskulkaew, Chatchawan ., Parvataneni, Kesav., Ballout, Hussien.,
Sharma, Tarun., Almahmoud, Mohamed., Ketron, Lowell., Szpunar, Susan
., LaLonde, Thomas, Mehta, Rajendra., Yamasaki, Hiroshi.
Oral presentation at the American College of Physicians-Michigan
associate meeting
Myxedema Coma in a Patient with End Stage Renal Disease on Thyroid
Replacement Therapy
Almahmoud, Mohamed Faher., Alamiri, Khaled., Russel, Sherilyn.
Poster presentation at the American College of Physicians-Michigan
associate meeting
Moyamoya Syndrome in a 28-year old female with Systemic Lupus
Erythematous
Hassanali, Alia., Almahmoud, Mohamed Faher., Qaqish, Nicole..
Poster presentation at the American College of Physicians-Michigan
associate meeting
Implications of Transesophageal Echocardiography on the Diagnosis and
Management of Implantable Cardiac Device Infections
Almahmoud, Mohamed Faher., Fishbain, Joel., Othman, Hussein.,
Sabbagh, Salah., Szpunar, Susan
Poster Presentation at St.John hospital Annual research day
National
2012 Hemophagocytic lymphohistocytosis syndrome
Almahmoud, Mohamed Faher., Andreeff, Michael.
Oral presentation at the weekly meeting of the leukemia
department at MD Anderson Hospital, University of Texas
in Houston, Texas
73
2012 Incidence of Arterial and Venous Thrombosis in Von Willebrand Disease
2014
2015
2015
2015
2016
Hassan, Syed., Qureshi, Waqas., Amer, Syed., Almahmoud, Mohamed.,
Dabak, Vrushali S., Kuriakose, Philip.
Oral presentation at the 2012 Annual Meeting of the American Society of
Hematology in Atlanta, Georgia
Outcomes of Laser-Assisted Balloon Angioplasty versus Balloon
Angioplasty Alone for Below Knee Peripheral Arterial Disease
American College of Cardiology 63rd Annual Scientific Session and
TCT@ACC-i2, Washington, DC, USA
J Am Coll Cardiol. 2014;63(12_S):. doi:10.1016/S0735-1097(14)62142-2
The Role of Transesophageal Echocardiography in Extraction of Infected
Cardiac Implantable Electrophysiological Devices
Almahmoud, Mohamed Faher., Fishbain, Joel., Othman, Hussein.,
Sabbagh, Salah., Szpunar, Susan..
American College of Cardiology 64th
Annual Scientific Session and
TCT@ACC-i2,
San Diego, CA, USA
J Am Coll Cardiol. 2015;65(10_S):. doi:10.1016/S0735-1097(15)60320-5
Electrocardiographic versus Echocardiographic Left Ventricular
Hypertrophy in Prediction of Congestive Heart Failure in the Elderly
Almahmoud, Mohamed Faher., Soliman, Elsayed., Qureshi, Waqas.,
O'neal, Wesley.
Moderated poster abstract presentation
American Heart Association, Epi/lifestyle Scientific Sessions, Baltimore,
MD, USA
Circulation.2015; 131: AMP55
Resting heart rate and incident atrial fibrillation in the elderly
Almahmoud, Mohamed Faher., Soliman, Elsayed., O'neal, Wesley.
Poster abstract presentation
American Heart Association, Epi/lifestyle Scientific Sessions, Baltimore,
MD, USA
Circulation.2015; 131: AP102
Left Ventricular Hypertrophy by Electrocardiogram versus Cardiac
Magnetic Resonance Imaging as a Predictor for Heart Failure: The MESA
study
Oseni, Abdullahi O., Qureshi, Waqas T., Almahmoud, Mohamed Faher.,
Bertoni, Alain., Bluemke, David A., Hundley, William G., Lima, Joao
A.C., Herrington, David M., Soliman, Elsayed Z.
Moderated poster presentation
American Heart Association, Epi/lifestyle Scientific Sessions, Phoenix,
AZ, USA. Circulation.2016;133: AMP31
74
2016 Fibroblast Growth Factor-23 and Cardiac MRI indices of Myocardial
Fibrosis in the Multi-Ethnic Study of Atherosclerosis
Almahmoud, Mohamed Faher., Herrington, David., Hundley, W., Jordan,
Jennifer., Kestenbaum, Bryan., Katz, Ronit., Michos, Erin., Liu, Chia-
Ying., Venkatesh, Bharath Ambale., Lima, Joao.
American College of Cardiology 65th
Annual scientific session & Expo,
2016, Chicago, IL, USA
International
2008 Updates in Rheumatoid Arthritis management
Almahmoud, Mohamed Faher.
Oral presentation at the University of Aleppo 50th Anniversary Meeting.
Report of Clinical Activities and Innovations
Current Licensure and Certification
2010 Educational Commission for Foreign Medical Graduates
2014
Controlled Substance Registration Certificate
2014
2014
2015
2015
2015
North Carolina Medical Board, Physician License Certificate
Council on Epidemiology and Prevention, Participation as a Fellow in the
40th
Ten-Day Seminar on the Epidemiology and Prevention of
Cardiovascular Disease
July 28-August 8, 2014
American Heart Association Basic Life Support (BLS) for healthcare
providers (CPR and AED) program.
May 20th
, 2017
American Heart Association Advanced Cardiovascular Life Support
(ACLS) program.
May 20th
, 2017
West Virginia Medical Board, Physician License Certificate
75
Practice Activities
2014
2014
2014
Cardiovascular Research Fellow at Wake
Forest University, School of Medicine
Master of Science in Clinical and
Population Translational Sciences at
Wake Forest University, School of
Medicine
Instructor of Internal Medicine at Wake
Forest Baptist Hospital
Report of Education of Patients and Service to the Community
Activities
2012
2015
Diabetic Educations at St. John Hospital Diabetes Clinic
Role: educating patients about current management of diabetes
Triad Health free community clinic
Role: volunteering primary physician
Report of Scholarship
Publications
1- Resting heart rate and incident atrial fibrillation in the elderly
O'neal, Wesley T., Almahmoud, Mohamed Faher., Soliman, Elsayed Z..
Pacing Clin Electrophysiol. 2015 May;38(5):591-7. doi: 10.1111/pace.12591. Epub
2015 Feb 17
2- The Role of Transesophageal Echocardiography in Extraction of Infected
Cardiac Implantable Electrophysiological Devices
Almahmoud, Mohamed Faher., Fishbain, Joel., Othman, Hussein., Sabbagh, Salah.,
Szpunar, Susan.
Abstract: J Am Coll Cardiol. 2015;65(10_S):. doi:10.1016/S0735-1097(15)60320-5
3- Outcomes of Laser-Assisted Balloon Angioplasty versus Balloon Angioplasty
Alone for Below Knee Peripheral Arterial Disease
76
Piyaskulkaew,Chatchawan., Parvataneni, Kesav., Ballout, Hussien., Sharma, Tarun.,
Almahmoud, Mohamed.,Ketron, Lowell., Szpunar, Susan., LaLonde, Thomas., Mehta,
Rajendra., Yamasaki, Heroshi.
Abstract: J Am Coll Cardiol. 2014;63(12_S):. doi:10.1016/S0735-1097(14)62142-2
4- Electrocardiographic and Echocardiographic Left Ventricular Hypertrophy
in the Prediction of Stroke in the Elderly
O'neal, Wesley T., Almahmoud, Mohamed Faher., Qureshi, Waqas T., Soliman, Elsayed
Z..
J Stroke Cerebrovasc Dis. 2015 Jul 4. pii: S1052-3057(15)00314-6. doi:
10.1016/j.jstrokecerebrovasdis.2015.04.044
5- Electrocardiographic versus Echocardiographic Left Ventricular
Hypertrophy in Prediction of Congestive Heart Failure in the Elderly
Almahmoud, Mohamed Faher., O'neal, Wesley T., Qureshi, Waqas T., Soliman, Elsayed
Z..
Clin. Cardiol. 38, 000-000 (2015) DOI:10.1002/clc.22402
6- Outcomes of Correcting Hyponatremia in Patients with Myocardial
Infarction
Qureshi, Waqas., Hassan, Syed., Khalid, Fatima., Almahmoud, Mohamed Faher., Shah,
Bhavik., Tashman, Ra'ad., Ambulgekar, Nikhil., El-Refai, Mostafa., Mittal, Chetan.,
Alirhayim, Zaid..
Clin Res Cardiol. 2013 Sep;102(9):637-44. doi: 10.1007/s00392-013-0576-z. Epub 2013
May 8.
7- Incidence of Arterial and Venous Thrombosis in Vonwillebrand Disease
Hassan, Syed. Qureshi, Waqas., Amer, Syed., Almahmoud, Mohamed., Dabak, Vrushali
S., Kuriakose,Philip.
322. Disorder of Coagulation or Fibrinolysis I, Blood (ASH annual Meeting Abstracts)
2012 120: Abstract 101
AMER SOC HEMATOLOGY 2021 L ST NW, SUITE 900, WASHINGTON, DC 20036 USA
Conference: BLOOD, Volume: 21
8- Laser in infrapopliteal and popliteal stenosis 2 study (LIPS2): Long-term
outcomes of laser-assisted balloon angioplasty versus balloon angioplasty for below
knee peripheral arterial disease
Piyaskulkaew, Chatchawan., Parvataneni, Kesav., Ballout Hussein., Szpunar, Susan.,
Sharma, Tarun., Almahmoud, Mohamed., Davis, Thomas., Mehta, Rajendra H.,
Yamasaki, Hiroshi. Catheter Cardiovasc Interv. 2015 Dec 1;86(7):1211-8. doi: 10.1002/ccd.26145. Epub 2015 Oct 22.
9- Left Ventricular Hypertrophy by Electrocardiogram versus Cardiac
Magnetic Resonance Imaging as a Predictor for Heart Failure: The MESA study
77
Oseni, Abdullahi O., Qureshi, Waqas T., Almahmoud, Mohamed Faher., Bertoni, Alain.,
Bluemke, David A., Hundley, William G., Lima, Joao A.C., Herrington, David M.,
Soliman, Elsayed Z.
Moderated poster presentation
American Heart Association, Epi/lifestyle Scientific Sessions, Phoenix, AZ, USA
Circulation.2016;133: AMP31
10- Assisted Reproductive Techniques
Almahmoud, Mohamed Faher., Mohsen, Mousa. (2009, June 10).
Book, Aleppo Publications, Pub Status: Published.
Professional educational materials or reports, in print or other media
1- Heparin Induced Thrombocytopenia in Patients with Cancer
Clinical Research
2- The Role of Transesophageal Echocardiography in Extraction of Infected Cardiac
Implantable Electrophysiological Devices
Clinical Research
3- Failure rates after Arteriovenous Fistula creations
Clinical Research
4- Changes in Plasma Volume as a Prognostic Marker in Myocardial Infarction
Clinical Research
5- Manuscript Reviewer for Frontiers in Medicine Journal 2014:
Cardiovascular epidemiology
6- Fibroblast Growth Factor 23 and Myocardial Fibrosis in Multi-Ethnic Study of
Atherosclerosis using Cardiac Magnetic Resonance T1-Mapping
Accepted proposal
7- Relationship Between Cardiac Structure, Function and Mechanics with
Neurocognition in the Hisopanic Community Health Study/Study of Lations (SOL)
Echocardiographic Study of Lations (Echo-SOL) Ancillary Study
Accepted proposal
8- Electrocardiographic versus Cardiac Magnetic Resonance Left Ventricular
Hypertrophy in Prediction of Congestive Heart Failure in the Mutli-Ethnic Study of
Atherosclerosis
Accepted proposal
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9- I was an Ad hoc reviewer for Catheterization and Cardiovascular Interventions
Journal. 2015
Work Experience
11/2012 - 12/2012 Average Hours/Week: 60
MD Anderson Hospital/University of Texas, Texas Rotating Resident, with Dr. Michael Andreeff
I worked as a rotating resident at the leukemia department at MD Anderson Hospital.
During this rotation, I had exposure to inpatient and outpatient clinical cases of
leukemia and attended conferences and lectures about emerging researches in the
field of oncology and leukemia at MD Anderson hospital; also I did a presentation
about hemophagocytic lymphohistocytosis syndrome at the leukemia department.
03/2011 - 06/2011
Al Fatih Hospital, Syrian Arab Republic ER Physician, with Dr. Mahmoud, Haj Mohamed
I worked in the ER Department as an assistant physician.
During this period, I managed medical, surgical and pediatric emergencies.
12/2009 - 01/2010
Suny Downstate University, New York Medical Student, with Dr. Nicholas Shorter
I rotated as a medical student in the Pediatric Surgery Department with Dr.Shorter.
I helped in all pediatric operations and interventions at King's County Hospital and
Downstate Hospital. This was an elective that I did during my medical education.
11/2009 - 12/2009
Suny Downstate University, New York Medical Student, with Dr. JEFFREY WEISS
I rotated as a medical student in the department of Urology with Dr.Weiss. I
participated in inpatient and outpatient urological services.
I also helped in many different Urological operations and interventions.
10/2008 - 11/2008
American University of Beirut, Lebanon Medical student, with Dr. Mahmoud Choucair
I rotated as a medical student elective at the department of Internal Medicine at the
American University of Beirut Hospital, where I had exposure to inpatient and
outpatient general medicine, cardiology and neurology patients.
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Volunteer Experience 12/ 2010 - 01/2011
Wayne state University, Michigan Rotating Physician, with Dr. Theodore Jones
I worked at Hutzel Women's Hospital in the department of OB/GYN as a rotating
physician.
I rotated mainly in the Department of Labor and delivery, and also helped in the
OB/GYN operations.
10/2014- 01/2015
Wake Forest University School of Medicine
Participated in the WFU School of Medicine admission interviews.
Current/Prior Training 07/2015
Cardiovascular research fellowship, NIH T32 training grant (Mentor- David
Herrington), Wake Forest School of Medicine, July 2015-June 2016
07/28-08/08, 2014
Council on Epidemiology and Prevention, Participation as a Fellow in the 40th
Ten-Day Seminar on the Epidemiology and Prevention of Cardiovascular
Disease Lake Tahoe, CA, USA
07/2011 – 06/2014
Internal Medicine residency
St John Hospital and Medical Center Program, Grosse pointe Woods, Michigan Internal Medicine
Raymond C Hilu
Rozzell, Donald
11/2012 - 12/2012
Internal Medicine residency
Md Anderson Cancer center/university of Texas, Houston, Texas
Internal Medicine
Philip R Orlander
Michael Andreeff
Other Awards/Accomplishments
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1-Syrian Youth organization award and medal for first place in Arabesque art 1994
2-Aleppo Youth organization award and medal for first place in Arabesque and
Arabic calligraphy 1994-1995-1996
3-University of Aleppo soccer championship 2006 second place
4-University of Aleppo soccer championship 2007 first place
5-University of Aleppo soccer championship 2008 second place
6-University of Aleppo soccer championship 2009 first place
7-Medical school soccer championship 2010 First place
8-Medical school soccer championship top scorer 2010
9-Top 10 Medical students honor