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Functional Significance of Elevated Mitral Gradients Following Repair for
Degenerative Mitral Regurgitation
Chan et al: Mitral Stenosis After Mitral Valve Repair
Kwan Leung Chan, MD, FRCPC*; Shin-Yee Chen, MD, FRCPC*;
Vincent Chan, MD, FRCSC*; Karen Hay, RDCS*; Thierry Mesana, MD, FRCSC*;
Buu Khanh Lam, MD, FRCSC*
*University of Ottawa Heart Institute
Correspondence to Kwan Leung Chan, MD FRCP University of Ottawa Heart Institute 40 Ruskin Street, H3412 Ottawa, ON K1Y 4W7 Tel: 613-761-4189 Fax: 613-761-4170 Email: [email protected]
DOI: 10.1161/CIRCIMAGING.112.000688
Journal Subject Codes: Cardiovascular (CV) surgery:[38] CV surgery: valvular disease,
Diagnostic testing:[125] Exercise testing, Diagnostic testing:[31] Echocardiography
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Abstract
Background—We have observed that elevated mitral gradients (EMG) can develop in some
patients following mitral valve repair for degenerative mitral regurgitation.
Methods and Results—We screened 275 patients who had mitral valve repair involving more
than one leaflet scallop between October 2001 and July 2010. Mitral valve hemodynamics were
assessed at rest and at peak exercise using the cycle ergometer. B-type natriuretic peptide (BNP)
levels were measured at rest and after exercise. The patients also performed a 6 minute walk test
and SF36 questionnaire. We enrolled 110 patients, with resting mean mitral diastolic gradient
3 mm Hg in 35 patients (Group 1), and > 3 mm Hg indicative of EMG in 75 patients (Group 2).
Posterior mitral leaflet plication (P=0.04) and the use of a complete mitral annuloplasty ring
(P<0.0001) were associated with EMG. Group 2 patients had larger left atrial volume (P=0.02),
higher mitral gradients at peak exercise and higher pulmonary artery systolic pressure at rest and
peak exercise, and lower exercise capacity (101±40 Watts versus 122 51 Watts, P=0.02). Group
2 patients also had higher BNP levels, and lower scores in 3 SF36 health concepts. Multivariate
regression analyses showed that mitral valve area was an independent predictor of maximum
exercise capacity (P=0.003).
Conclusions—Following mitral valve repair for degenerative mitral regurgitation EMG is not
uncommon, and is associated with worse intracardiac hemodynamics, higher BNP levels, lower
exercise capacity and poorer quality of life. Further refinement in the surgical technique may
reduce the incidence of this complication.
Key Words: mitral regurgitation, mitral valve repair, mitral stenosis, exercise capacity, quality
of life
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Mitral regurgitation (MR) is the most common valvular dysfunction affecting the general
population and its prevalence increases with age.1 The most common cause for primary MR is
degenerative/myxomatous mitral valve (MV) disease.2 In patients with severe MR due to
degenerative MV disease, the treatment of choice is MV repair which avoids the complications
associated with prosthetic valves and may provide a better long term survival compared to mitral
valve replacement.3-9 The procedure of MV repair consists of correction of the specific
component of the MV apparatus responsible for the abnormal coaptation leading to MR, and
remodeling of the mitral annulus by an annular ring or band. Resection of redundant leaflet
tissue particularly involving the posterior mitral leaflet can involve more than one third of the
leaflet, resulting in a significant reduction of the leaflet area and restricted excursion of the
posterior mitral leaflet.9-12
We hypothesize that MV repair involving more extensive tissue resection could result in elevated
mitral gradients (EMG) consistent with functional mitral stenosis (MS) which in turn could
affect the patient’s functional capacity and quality of life. The objectives of the present study
were to assess the prevalence and functional significance of EMG following MV repair for
degenerative MR by a comprehensive evaluation of resting and exercise MV hemodynamics,
exercise capacity and personal well being.
Methods
Patient Population:
From October 2001 to July 2010, MV repair was performed in 455 patients by a single surgeon
for severe MR due to myxomatous degeneration of the MV. Of these patients, 275 patients
(60%) had excess of MV tissue involving more than one leaflet scallop and were screened for
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enrolment into the study, as it was our hypothesis that functional MS may be more prevalent in
this subset of patients who required more aggressive tissue resection. The patients were
recruited and studied between December 2009 and April 2011. Patients who had residual MR
greater than mild in severity following MV repair were excluded. We also excluded hospitalized
patients, patients with prior myocardial infarction, left ventricular dysfunctionl with ejection
fraction < 40%, concomitant aortic valve disease with > mild stenosis or regurgitation, and
inability to perform bicycle exercise test. The patients underwent exercise echocardiography
using the supine bicycle protocol to assess exercise capacity and intracardiac hemodynamics
including MV diastolic gradients, severity of MR, and pulmonary artery systolic pressure at rest
and peak exercise. The 6 minute walk test was performed to provide an additional assessment of
the functional capacity.13,14 B-type natriuretic peptide (BNP) levels at rest and following
exercise were measured. The SF36 questionnaire was completed by all patients to measure their
functional health status. The study protocol was reviewed and approved by the Research Ethics
Board, and informed consent was obtained from all patients.
Resting Echocardiographic Measurements:
The echocardiographic measurements were obtained in accordance with the guidelines of the
American Society of Echocardiography.15 The left ventricular ejection fraction was calculated
using the modified Simpson’s rule.
Supine Bicycle Exercise Echocardiography:
The patients were securely positioned on a supine tilting cycle ergometer table that allowed up to
40 tilt. The patient pedaled at a steady state against a fixed resistance. After an initial workload
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of 25 Watts maintained for two minutes, the workload was stepwisely increased by 25 Watts
every two minutes. This was a symptom-limited exercise test and the patients were encouraged
to exercise to exhaustion.
Mitral Valve Hemodynamics:
The MV hemodynamics were measured by Doppler at rest and peak exercise. The peak and
mean transmitral pressure gradients were calculated using the modified Bernoulli equation, and
the MV area was calculated by the continuity equation by dividing the left ventricular outflow
tract stroke volume by the integral of the diastolic mitral transvalvular velocity.16 The
pulmonary systolic pressure was calculated based on the tricuspid regurgitant velocity and the
estimated right atrial pressure.17 Severity of MR was assessed according to the published
guidelines.18
We studied 20 patients with no structural heart disease who were referred for echocardiograms.
None had > mild MR. They were matched for age (60.0 4.3 years) and sex (14 men and 6
women), and they also had similar resting heart rate (72.0±12.5 beats per minute) compared to
the study patients. The resting mitral mean diastolic gradient was 1.24 0.52 mm Hg (range 0.62
to 2.70 mm Hg). Thus, in the analysis of MV repair patients, a resting mitral diastolic gradient >
3 mm Hg was used to indicate the presence of EMG.
6-minute Walk Test:
The 6-minute walk test was performed on the same day as the exercise echocardiogram, after the
patients rested for at least one hour.13,14
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B-type Natriuretic Peptide:
Fasting blood samples were drawn to measure B-type natriuretic peptide (BNP) on the day of the
exercise echocardiogram. The measurement was based on the rapid enzyme-linked
immunosorbent assay using the Biosite Triage kits. To assess the effect of exercise on BNP, a
second blood level was measured 15 minutes after the exercise echocardiogram.
SF-36 Questionnaire:
Health-related quality of life assessment was performed using the Medical Outcome Trust short
form 36 Item Health Survey (SF36), which has well established psychometric properties and has
been shown to have high reliability and validity.19
Statistical Analysis:
Descriptive statistics were used to summarize data: categorical data were described using
frequencies and percentages with comparative evaluations carried out via the chi-square test, or
Fisher’s exact test for frequency <5; continuous variables were presented as mean + standard
deviation, and comparisons of continuous variables were performed using the Student’s t-test for
normally distributed data and the Wilcoxon rank-sum test to adjust for skewed distributions. In
addition, when applicable, one-way ANOVA testing were used to assess inter-group variations
with the maximum experimentwise error rate (MEER) being controlled by a t-test with
Bonferroni correction or the Kruskal-Wallis nonparametric analogue test when the assumption of
normality for an ANOVA was not met. All exploratory correlation analyses were performed
using the Pearson (r) and Spearman (rs) correlation coefficients. In addition to hypothesis-
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generating exploratory correlations to determine the interaction of patient characteristics and
exercise capacity, multivariable regression models were constructed, while controlling for EMG
functional MS, to explore possible factorial associations. All significant covariates were entered
into a multivariable logistic regression model in a forward stepwise manner with a liberal entry
criterion of P<0.15 and a stay criterion of P<0.05. Model goodness of fit was assessed using
chi-square statistics and the Hosmer-Lemeshow test. Statistical significance was set at P < 0.05.
All analyses were performed using the SAS statistical software (SAS v9.1; SAS, Cary, NC).
Results
Baseline Patient Characteristics
We screened 275 patients and enrolled 110 (40.0%) patients into the study. The reasons for
exclusions are shown on Table 1. One main reason for exclusion was that our institute is a
tertiary referral centre and many patients did not reside in our region. Resting mitral mean
diastolic gradient 3 mm Hg was present in 35 patients (Group 1) and > 3 mm Hg in 75 patients
(Group 2). The time interval since surgery was 4.2 ± 2.3 and was shorter in Group 1 patients (P
= 0.0002). There were no statistically significant differences between the 2 groups in
demographics including age, sex distribution, and body mass index.(Table 2). Prolapse or flail
involving the posterior mitral leaflet was the most common leaflet abnormality in both groups,
whereas isolated anterior mitral leaflet abnormality was uncommon.
Techniques of MV Repair
The details of the repair are presented in Table 3. Plication of the posterior mitral leaflet was
performed in 8 Group 2 patients (11%) but none in Group 1 patient; (P=0.04). All but 3 patients
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(97%) had annuloplasty with a posterior band or ring. Annular ring (mean size 30.5 ± 2.1 mm)
was implanted in 41(55%) of the Group 2 patients, but in only 1 Group 1 patient (3%) (P<0.001),
whereas annular band was used in 32 Group 1 patients and 33 Group 2 patients with a trend for a
smaller band size in Group 2 (31.3 ±2.9 mm versus 30.0 ± 2.5 mm, P = 0.07). The Cox Maze
procedure, tricuspid valve annuloplasty and concomitant coronary bypass surgery were
performed with similar frequencies in both groups.
Resting Echocardiographic Data
The left ventricular dimensions and ejection fraction were normal and similar in both groups of
patients (Table 4). Not surprisingly, the indexed left atrial volume was greater in Group 2
patients than in Group 1 patients (P=0.02).
Mitral Valve Hemodynamics:
The resting heart rate was higher in patients in Group 2, but the heart rates at peak exercise were
similar between the two groups. The calculated mitral valve area was smaller in patients in
Group 2 (Table 4). There were no statistically significant correlations between resting
hemodynamics and clinical characteristics including age, sex and time duration since surgery.
There were 29 patients with resting mean mitral gradient 5-10 mm Hg, and 3 patients with
resting gradient > 10 mm Hg. The differences between the 2 groups in diastolic mitral gradients
were magnified at peak exercise (P<0.0001). Mild MR was present in 20 patients (6 in Group 1
and 14 in Group 2, P=0.85), and only 4 patients in Group 2 had an increase in MR severity by
one grade from rest to peak exercise, including 3 patients from none to mild, and one patient
from mild to moderate MR. No patients had > 1 grade increase in MR during exercise. The
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pulmonary artery systolic pressure remained higher in Group 2 patients at rest and at peak
exercise (P=0.02), and correlated with resting mean diastolic MV gradient (r=0.47, P<0.0001;
r=0.46, P<0.0001 respectively).
Functional Assessment
The bicycle exercise test showed that Group 2 patients had lower exercise capacity with shorter
exercise durations and lower Watts and METS (Table 5). However, there was no significant
difference between the two groups in the 6-minute walk distance which is a submaximal exercise
test.
Both the baseline and post exercise BNP levels were higher in Group 2 patients.
The SF36 questionnaire showed significant differences between the 2 groups in three of the eight
domains: Physical Functioning, Vitality and General Health (Table 5).
Maximum exercise capacity in Watts correlated with age (r=-0.51, P<0.0001), MV mean
diastolic gradient at rest (r=-0.23, P=0.015) and at peak exercise (r=-0.22, P=0.02), MV area
(r=0.48, P<0.001), pulmonary artery systolic pressure at rest (r=-0.48, P<0.0001) and at peak
exercise (r=-0.21, P=0.03), and BNP at rest (r=-0.54, P<0.0001) and post exercise (r=-0.45,
P<0.0001). There was also association between maximum exercise capacity with gender
(125 28 Watts in men and 68 40 Watts in women, P=<0.0001) and 2 of the SF36 component
scales which were Physical Functioning (r=0.58, P<0.0001) and Vitality (r=0.31, P=0.0001).
Using multivariable regression analysis, we identified young age (P<0.0001), male gender
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(P<0.0001), MV area (P=0.003), BNP at rest (P=0.02) and SF36’s Physical Functioning
(P=0.015) as independent predictors of better exercise capacity. Additional exploratory models
controlling for EMG did not identify any additional clinical factors associated with exercise
capacity.
Discussion
In the past three decades, MV repair has become the preferred surgical procedure in the
treatment of patients with severe degenerative MR.5-7,20-22 The procedure frequently involves
resection of a portion of the posterior mitral leaflet and some form of mitral annuloplasty to
remodel the annulus and to support the leaflet repair.10-12 These anatomic alterations suggest that
some degree of MS may be a sequela following MV repair. The present study is the first study
to systematically assess patients with more extensive myxomatous changes following MV repair
for the development of EMG, and showed a varying degree of MS ranging from mild to severe in
many of these patients. Whether EMG of the magnitude reported in this study is indicative of
MS may be controversial. On the other hand, EMG of similar magnitude following MV
annuloplasty for ischemic MR has been reported in several recent studies.23-26 In 123 such
patients Williams et al reported mean diastolic MV gradient > 5 mm Hg in 54% and > 8 mm Hg
in 13% of patients, with only about 10% of these patients having moderate or severe MR.24 The
term “functional MS” was introduced in studies of patients who underwent surgical annuloplasty
for ischemic MR.23-26 Kainuma et al reported the presence of functional MS in 58 patients post
surgical annuloplasty for ischemic MR and the mean diastolic mitral gradient was 2.9 +/- 1.1 mm
Hg in their patients.26 Magne et al and Kubota et al also reported the ubiquitous presence of
functional MS in similar patients and both studies included a controlled group.23, 25 In the study
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by Magne et al, the 20 controls were patients with coronary artery disease and left ventricular
dysfunction and the mean mitral gradient was 2 +/- 1 mm Hg whereas the controls in the study
by Kubota et al were healthy individuals with normal left ventricular function and a mean mitral
gradient of 0.6 +/- 0.2 mm Hg, in comparison to 6 +/- 2 mm Hg and 3.5 +/- 2.7 mm Hg in the
annuloplasty patients in the two studies respectively. Complete rings were used with the average
size being 24.7 mm in the study by Magne et al and 28.0 mm in the study by Kubota et al.23,25
The mitral gradients in our controls are similar to that reported by Kubota et al.25
Magne et al reported that functional MS diagnosed by the presence of this low magnitude of
EMG was associated with elevated pulmonary pressures and worse functional capacity.23 It is
noteworthy that functional MS evidenced by EMG was present in the absence of leaflet
abnormalities and even when the annuloplasty ring was not undersized.25
Although MS in our patients was generally mild, moderate to severe MS can occur in some
patients. The development of MS appears intrinsic to the repair procedure, as the increased
mitral gradients are observed shortly following the procedure. This is different from the late and
unusual occurrence of MS years after MV repair due to excessive fibrous tissue at the annular
ring extending onto the leaflets.27-29
As there are no prior studies on EMG in patients with MV repair for degenerative MR, we
included a control group to establish the normal limits of mitral valve gradients, even though the
concept of functional MS has been developed in patients with surgical annuloplasty for ischemic
MR showing that a mean diastolic mitral gradient > 3 mm Hg was likely abnormal.23-26 The data
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in our controls provided further evidence that mean diastolic mitral gradient > 3 mm Hg was
abnormal and indicative of MS.
Clinical Significance of EMG
The functional significance of EMG in these patients has not been well recognized.4,5,11 Before
MV repair, many patients may have poor exercise endurance due to occult or overt heart failure
as a result of severe MR. They would experience improvement in their symptoms following MV
repair which drastically reduce MR, and thus may not recognize mild persistent limitation due to
the presence of MS which is mild in most instances. Furthermore, some of the patients are
elderly or sedentary, such that a mild or even moderate degree of limitation to their exercise
endurance may not be recognized. Without comprehensive assessment, mild limitation due to
incomplete recovery would be difficult to recognize by the patient or the physician.
Despite only mild EMG consistent with mild MS in the majority of cases, there was functional
and physiologic impact on the patients. Patients with functional MS had larger left atrial
volumes, and MV area was an independent predictor of exercise capacity. The physiological
importance of EMG is further supported by the higher levels of BNP indicative of elevated
intracardiac pressures, and higher pulmonary artery systolic pressures both at rest and at peak
exercise, consistent with the presence of functional MS in these patients. The adverse impact of
functional MS was further evidenced by the reduced exercise capacity demonstrated by the
exercise bicycle test, which is a better test for maximum exercise capacity than the 6-minute
walk test.
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Patients with EMG had a poorer quality of life, with lower scores in three of the SF36
component scales indicating that they were more limited in physical activities, had less energy,
and perceived their personal health less favourably. Thus EMG should be looked for in patients
who remain limited despite apparently successful MV repair.
Implications for MV repair:
The present study showed a high prevalence of EMG following MV repair in patients with
myxomatous changes involving more than one leaflet scallop. Though largely mild in severity
EMG clearly had physiological and functional significance. Furthermore, EMG can be more
severe in some patients. Thus, avoiding EMG should be an objective of a successful MV repair.
The use of a complete ring was associated with a higher incidence of EMG, suggesting that a
band or an incomplete ring should be considered and undersizing with an annular band should be
avoided to reduce the risk of EMG. Minimizing the amount of mitral leaflet resection and leaflet
plication may also be useful. It is interesting that EMG has also been described in patients who
undergo restrictive annuloplasty for ischemic MR, highlighting that EMG can occur in the
setting of an undersize annular ring without leaflet resection and may even be present with a
properly sized ring.23-26
The mechanism of EMG in these patients require further study. Obstruction can occur at the
annulus and the leaflet level.25 The placement of an annular ring not only alters the antero-
posterior and transverse diameters of the annulus, but it also limits the expansion of the annulus
which is essential to the opening of MV orifice.30 In patients following MV annuloplasty for
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ischemic MR, Kubota et al observed a substantial difference between the calculated MV area
using the continuity equation and the calculated geometric MV annular area (1.6 +/- 0.2 cm2
versus 3.3 +/- 0.5 cm2, p < 0.01), even though the MV leaflets were normal without thickening or
commissural fusion. They proposed that MS in their patients was largely due to restricted
diastolic leaflet excursion.25 This may also be the case in our patients whose posterior MV
leaflet frequently showed restricted excursion. Geometric measures such as the MV annular area
can be misleading and should not be used to assess stenosis severity, because it does not take into
consideration the flow properties.31 Serial obstruction at both the MV annulus and the leaflets is
plausible. Real time 3-dimensional echocardiography appears to be a promising imaging
modality in assessing the mechanism of EMG in these patients.32
Limitations
The patients were recruited from a large series of MV repair by a single surgeon with a
recognized expertise in this procedure.33 We enrolled patients with more severe myxomatous
changes requiring more extensive tissue resection, which made up 60% of our MV repair
population and may partly explain the high prevalence of EMG in the study. Future studies
should include patients with limited focal MV involvement to have a better perspective of the
prevalence of EMG in MV repair population as a whole. The surgical techniques employed in
the present study are widely used, but have been evolving such that the use of an incomplete ring
or band had become more common in the more recent cases. It is possible that our findings may
not be applicable to other surgical centers, particularly if different techniques are used for MV
repair. We included only ambulatory patients such that patients with severe EMG may be under-
represented as they would be more likely to have heart failure and be hospitalized. Group 2
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patients had higher resting heart rates which may have contributed to the increased MV
gradients. The MV area which is independent of heart rate was significantly different between
the 2 groups. At peak exercise with similar heart rates in both groups the MV gradients
remained significantly higher in patients in Group 2, indicating that the difference in resting
heart rate likely had a small role in accounting for the differences in MV gradients between the
two groups. It can be argued that the definition of EMG is too liberal resulting in a high
prevalence but this definition was based on the findings in matched controls and supported by
the findings in studies on MV annuloplasty for ischemic MR. Furthermore the validity of this
definition was supported by the exercise data and the functional questionnaire, both of which
showed that EMG with mitral diastolic gradient > 3 mm Hg had physiologic and functional
importance. Even with a more restrictive definition such as mean mitral gradient > 5 mm Hg, 32
patients (29%) following MV repair would be considered to have EMG. The 6-minute walk test
is a sub-maximal exercise test and provides a useful indication of functional capacity in patients
with more advanced heart conditions such as pulmonary hypertension and severe heart failure,
but it is not an appropriate test to assess maximum exercise capacity in patients with less
advanced diseases.13,14 The sample size was modest and the findings may be subject to type I
and type II errors. Further studies to validate our findings will be beneficial.
Conclusion
Following MV repair for degenerative MR, EMG can develop in many of these patients. The
development of EMG has an adverse effect on the exercise mitral hemodynamics, exercise
capacity, BNP levels and the patient’s perception of well being. Further refinement in the
questionnaire, , ,, ,, , bbbbbbb
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surgical technique such as the avoidance of a complete ring may decrease the incidence of EMG
following MV repair.
Sources of Funding
Supported in part by the University of Ottawa Heart Institute Academic Medical Organization
Innovation Fund.
Disclosures
None.
References
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G zheart diseases: a population-based study Lancet 2006;368:1
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22. Gillonov AM, Blackstone EH, Nowicki ER, Slisatkorn W, Al-Dossari G, Johnston DR, George KM, Houghtaling PL, Griffin B, Sabik JF 3rd, Svensson LG. Valve repair versus valve replacement for degenerative mitral valve disease. J Thorac Cardiovasc Surg. 2008;135:885-93, 893. 23. Magne J, Senechal M, Mathieu P, Dumesnil JG, Dagenais F, Pibarot P. Restrictive annuloplasty for ischemic mitral regurgitation may induce function mitral stenosis. J Am Coll Cardiol. 2008;51:1692-701. 24. Williams ML, Daneshmand MA, Jollis JG Horton JR, Shaw LK, Swaminathan M, Davis RD, Glower DD, Smith PK, Milano CA. Mitral gradients and frequency of recurrence of mitral regurgitation after ring annuloplasty for ischemic mitral regurgitation. Ann Thorac Surg. 2009;88:1197-201. 25. Kubota K, Otsuji Y, Ueno T, Koriyama C, Levine RA, Sakata R, Tei C.. Functional mitral stenosis after surgical annuloplasty for ischemic mitral regurgitaton : importance of subvalvular tethering in the mechanism and dynamic deterioration during exertion. J Thorac Cardiovasc Surg. 2010;140:617-623. 26. Kainuma S, Taniguchi K, Daimon T, Sakaguchi T, Funatsu T, Kondoh H, Miyagawa S, Takeda K, Shudo Y, Masai T, Fujita S, Nishino M, Sawa Y; Osaka Cardiovascular Surgery Research (OSCAR) Group. Does stringent restrictive annuloplasty for functional mitral regurgitation cause functional mitral stenosis and pulmonary hypertension? Circulation. 2011;124 (suppl1):S97-106. 27. Tanaka K, Makuuchi H, Naruse Y, Kobayashi T, Hayashi I, Takayama T, Namifusa Y. Mitral stenosis due to fibrous tissue overgrowth after mitral valve repair. J Cardiovasc Surg. (Torino). 2003;44:59-60. 28. Nishida H, Takahara Y, Takeuchi S, Mogi K. Mitral stenosis after mitral valve repair using the duran flexible annuloplasty ring for degenerative mitral regurgitation. J Heart Valve Dis. 2005;14:563-4. 29. Ibrahim MF, David TE. Mitral stenosis after mitral valve repair for non-rheumatic mitral regurgitation. Ann Thorac Surg. 2002 ;73:34-6. 30. Okada Y, Shomura T, Yamaura Y, Yoshikawa J. Comparison of the Carpentier and Duran prosthetic rings used in mitral reconstruction. Ann Thorac Surg. 1995;59:658-62. 31. Garcia D, Kadem L. What do you mean by aortic valve area: geometric orifice area, effective orifice area, or Gorlin area? J Heart Valve Dis. 2006;15:601-8. 32. Hung J, Lang R, Flachskampf F, Shernan SK, McCulloch ML, Adams DB, Thomas J, Vannan M, Ryan T; ASE. 3D echocardiography: a review of the current status and future directions. J Am Soc Echocardiogr. 2007;20:213-233. 33. Verma S, Mesana TG. Mitral-valve repair for mitral valve prolapse. N Engl J Med. 2009;361:2261-9.
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Table 1. Reasons for Exclusion
Reason for Exclusion N (%)
Mitral valve replacement 11 (6.7)
Moderate or severe MR 8 (4.8)
Left ventricular dysfunction* 18 (10.9)
Unable to exercise 13 (7.9)
Refused to participate 18 (10.9)
Lived too far away 27 (16.4)
Unable to contact 36 (21.8)
Deceased 25 (15.2)
Others 4 (2.4)
Total 165 (100)
* left ventricular ejection fraction < 40%.
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Table 2. Patient Characteristics
All
(N=110)
Group1
Mean MV Grad
< 3mm Hg
(N=35)
Group 2
Mean MV Grad
> 3mm Hg
(N=75)
P
Age (yrs) 60 +/- 11.9 61 +/- 12.3 60 +/- 11.7 0.71
Male (%) 78 (71) 27 (77) 51 (68) 0.33
Hypertension (%) 34 (31) 9 (25) 25 (34) 0.35
Chronic renal
failure (%)
12 (11) 4 (12) 8 (10) 0.76
Smoking (%) 60 (55) 18 (51) 42 (56) 0.65
Atrial fibrillation
pre-op (%)
18 (17) 5 (15) 13 (17) 0.84
Body mass index
(kg/m2)
26.1 +/- 3.6 26.3 +/- 3.8 25.9 +/- 3.5 0.56
Blood pressure
(mm Hg)
Systolic 132 +/- 17 131 +/- 20 132 +/- 16 0.62
Diastolic 82 +/- 10 83 +/- 11 81 +/- 9 0.21
Mitral leaflet
pathology (%)
Anterior 2 (2) 1 (3) 1 (1) 0.56
25 ((34) )
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Posterior 60 (54) 19 (54) 41 (55) 0.58
Both 48 (44) 15 (43) 33 (44) 0.29
Time interval since
surgery (years)
4.2 +/- 2.3 3.1 +/- 1.5 4.8 +/- 2.4 0.0002
NYHA at follow-
up (%)
0.13
I 67 (61) 26 (74) 41 (55)
II 33 (30) 6 (17) 27 (36)
III 10 (9) 3 (9) 7 (9)
Atrial fibrillation
at follow-up
30 (27) 6 (17) 24 (32) 0.10
7 7 (9(9(( ) ) )
24 (3(3(3(3(3(332)2)2)2)2)2)2)
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Table 3. Surgical Characteristics
All
(N=110)
Group1
Mean MV Grad
< 3mm Hg
(N=35)
Group 2
Mean MV Grad
> 3mm Hg
(N=75)
P
Posterior mitral
leaflet
Resection 79 (72) 25 (71) 54 (72) 0.95
Plication 8 (7) 0 8 (11) 0.04
Sliding plasty 65 (59) 22 (63) 43 (57) 0.58
Anterior mitral leaflet
A1 repair 11 (10) 3 (9) 8 (11) 0.73
A2 repair 43 (39) 11 (31) 32 (43) 0.26
A3 repair 23 (21) 7 (20) 16 (21) 0.87
Commissuroplasty
Anterolateral 4 (4) 1 (3) 3 (4) 0.77
Posteromedial 5 (5) 2 (6) 3 (4) 0.69
MV Annuloplasty 107 (97) 33 (94) 74 (99)
Band 65 (59) 32 (91) 33 (44) <0.0001
Ring 42 (38) 1 (3) 41 (55) <0.0001
Tricuspid
annuloplasty
10 (9) 3 (9) 7 (9) 0.89
Cox maze 13 (12) 3 (9) 7 (9) 0.90
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procedure
Coronary bypass
surgery
14 (13) 6 (14) 8 (11) 0.34
A1, A2 and A3 refer to the lateral, mid and medial scallops of the anterior mitral leaflet.
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Table 4. Echocardiographic Variables
All
(N=110)
Group1
Mean MV Grad
< 3mm Hg
(N=35)
Group 2
Mean MV
Grad
> 3mm Hg
(N=75)
P
Resting Measures
LVEDD, mm 47.7 +/- 4.2 47.9 +/- 3.8 47.6 +/- 4.5 0.75
LVESD, mm 29.6 +/- 4.6 29.4 +/- 3.9 29.7 +/- 4.9 0.71
LV EF, % 63.3 +/- 5.9 62.7 +/- 6.4 63.6 +/- 5.7 0.47
LA Volume Index, ml/m2 39.5 +/- 12.7 35.6 +/- 10.9 41.3 +/- 13.1 0.02
LV Stroke Volume 82.3 +/- 23.9 87.4 +/- 26.1 80 +/- 22.6 0.13
Cardiac Output, l/min 5.8 +/- 1.6 5.7 +/- 1.5 5.9 +/- 1.6 0.68
Heart Rate, bpm 72.3 +/- 10.8 67.1 +/- 8.5 74.7 +/- 10.9 0.0004
MV Peak Gradient, mm
Hg
10.0 +/- 4.4 6.5 +/- 1.2 11.7 +/- 4.5 <0.0001
MV Mean Gradient, mm
Hg
4.5 +/- 2.4 2.5 +/- 0.3 5.5 +/- 2.4
MV Area, cm2 2.1 +/- 0.6 2.4 +/- 0.5 1.9 +/- 0.6 0.0005
MR (%) 20 (18) 6 (17) 14 (19) 0.85
PASP, mm Hg 33.3 +/- 9.6 28.6 +/- 5.7 35.5 +/- 10.2 .0003
Peak Exercise Measures
Heart Rate, bpm 121 +/- 24 122 +/- 26 121 +/- 24 0.86
29.7 +/- 4.4.4.4.4...99 99999
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82.3 +/- 23.9 87.4 +/- 26.1 80 +/- 22.6
m
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8882.2.22.33333 +/+/+///- 2223232 .999 8887.7.77.4444 4 +/+/+/+/+/- 22626262 11.11 888880000 /+//- 2222222222 66.666
imin 5.5.5.55 888 +/+/+/+/+/--- 1.1.1.11.66666 5.5.5.5.5 7 7 7 77 +/+/+/+/+ ----- 1.1.1.1 555 5.5.5.5.5.9 9 9 99 +/+/+++ - 111.666
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MV Peak Gradient, mm
Hg
21.9 +/- 10.1 15.6 +/- 6.4 24.8 +/- 10.2 <0.0001
MV Mean Gradient, mm
Hg
12.5 +/- 6.7 8.9 +/- 3.8 14.2 +/- 7.1 <0.0001
MR (%) 23 (21) 6 (17) 17 (23) 0.68
PASP, mm Hg 48.6 +/- 11.9 44.7 +/- 9.9 50.5 +/- 12.3 0.02
EF, ejection fraction; LA, left atrium; LVEDD, left ventricular end diastolic dimension; LVESD,
left ventricular end systolic dimension; MR, mitral regurgitation; MV, mitral valve; PASP,
pulmonary artery systolic pressure.
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Table 5. Functional Variables
All
(N=110)
Group1
Mean MV Grad
< 3mm Hg
(N=35)
Group 2
Mean MV Grad
> 3mm Hg
(N=75)
P
6-Minute Walk
distance, m
459 +/- 90 476 +/- 76 452 +/- 96 0.19
Cycle Ergometry
Exercise duration,
minutes
12.8 +/- 2.8 14.5 +/- 5.9 11.9 +/- 5.4 0.03
Exercise, Watts 108 +/- 45 122 +/- 51 101 +/- 40 0.02
Exercise, METS 5.8 +/- 1.7 6.3 +/- 2.0 5.6 +/- 1.5 0.04
BNP levels, pg/ml
Baseline 93.4 +/- 89 63.8 +/- 75.6 107.2 +/- 91.9 0.02
Post exercise 119 +/- 98 88.8 +/- 83.8 133 +/- 101 0.03
SF36
Physical Functioning 81.5 +/- 20.4 87.6 +/- 13.3 78.7 +/- 22.4 0.03
Vitality 61 +/- 21 68.3 +/- 17.6 57.5 +/- 21.7 0.01
General Health 69.2 +/- 18.5 77.7 +/- 13.0 65.2 +/- 19.4 0.0007
11.9 +/- 5.44
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Kwan Leung Chan, Shin-Yee Chen, Vincent Chan, Karen Hay, Thierry Mesana and Buu Khanh LamRegurgitation
Functional Significance of Elevated Mitral Gradients Following Repair for Degenerative Mitral
Print ISSN: 1941-9651. Online ISSN: 1942-0080 Copyright © 2013 American Heart Association, Inc. All rights reserved.
TX 75231is published by the American Heart Association, 7272 Greenville Avenue, Dallas,Circulation: Cardiovascular Imaging
published online September 6, 2013;Circ Cardiovasc Imaging.
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