Value of Index of Microvascular Resistance (IMR) in ... · Value of Index of Microvascular Resistance (IMR) in Microvascular Integrity Seung-Woon Rha, Korea University Guro Hospital,

Value of Index of Microvascular Resistance (IMR) in Microvascular

Integrity

Value of Index of Microvascular Value of Index of Microvascular Resistance (IMR) in Microvascular Resistance (IMR) in Microvascular

IntegrityIntegrity

Seung-Woon Rha, Korea University Guro Hospital,Myeong-Ho Yoon, Ajou University Hospital

Imaging & Physiology Summit 2009 Nov 20, 2009

Microvascular IntegrityMicrovascular Integrity

TMP gradeTMP gradeTMP grade

PcwPcw

• CFR• DDT, SAPV

• MVRI

•• CFRCFR•• DDT, SAPVDDT, SAPV

•• MVRIMVRI

To date, a simple and invasive method for assessing the integrity of coronary

microcirculation and myocardial viability in patients with AMI immediately after

primary angioplasty is lacking.

To date, a simple and invasive method for assessing the integrity of coronary

microcirculation and myocardial viability in patients with AMI immediately after

primary angioplasty is lacking.

Assessment of MicrovasculatureAssessment of Microvasculature

1. Noninvasive imaging

; Contrast Echo, MRI, RI scan, PET…

2. ECG; ST segment resolution

3. Coronary Angiography

;TIMI myocardial perfusion grade

4. Physiologic Studies

1) Coronary flow reserve,

2) other Doppler parameters

3) Index of Microcirculatory Resistance (IMR)

Microvascular resistanceMicrovascular resistance

PaPa

Collateral flow Collateral flow and pressureand pressure

PvPvPdPd

Microvascular circulationMicrovascular circulation-- Cell necrosisCell necrosis-- Cell edemaCell edema-- WBC, thrombotic materialsWBC, thrombotic materials

and platelets packingand platelets packing-- Spasm Spasm …………


TmnTmnRR

MethodsMethods

Intracoronary Pressure WireIntracoronary Pressure Wire(Radi Medical System, Uppsala, Sweden)(Radi Medical System, Uppsala, Sweden)Pa (mean Ao pr.), Pd (mean distal coronary pr.)Pa (mean Ao pr.), Pd (mean distal coronary pr.)TTmnmn (mean transit time)(mean transit time)Pcw (coronary wedge pressure), PcwPcw (coronary wedge pressure), Pcw--Pa ratio (Pcw/Pa)Pa ratio (Pcw/Pa)Thermodilution CFR = hyperemic TThermodilution CFR = hyperemic Tmnmn / basal T/ basal Tmnmn

FFR = hyperemic Pd / hyperemic PaFFR = hyperemic Pd / hyperemic PaIMR = Pd IMR = Pd hyperemic Thyperemic Tmnmn

Measurement of coronary pressure parametersMeasurement of coronary pressure parametersMeasurement of coronary pressure parameters

Intracoronary Doppler MeasurementsIntracoronary Doppler Measurements

Measurement of CFRMeasurement of CFR

Intracoronary Doppler MeasurementsIntracoronary Doppler Measurements

Measurement of DDTMeasurement of DDT

2 sec

240

0

120

cm/s

Intracoronary Pressure MeasurementsIntracoronary Pressure Measurements

ThrombusThrombus

Equalization : G/C pressure with the sensor

Equalization : Equalization : G/C pressure G/C pressure with the sensorwith the sensor

bPdbPd

bPabPa

PcwPcwhPdhPd

hPahPa

hPd/hPa = FFRhPd/hPa = FFRhPd/hPa = FFR

bTmnbTmnhTmnhTmn

bTmn/hTmn = CFRthermo

bTbTmnmn/hT/hTmnmn = = CFRCFRthermothermo

Pd hTmn = IMRPdPd hThTmnmn = = IMRIMR

SalineSalineSalineSalineSalineSaline

AdenosineAdenosine

IMRIMR

Resistance = ∆ Pressure / Flow

1 / Tmn ≅ Flow

IMR = (Pd – Pv) / (1 / Tmn)

IMR = Pd Tmn

at maximal hyperemia…

Resistance = ∆ Pressure / Flow

1 / Tmn ≅ Flow

IMR = (Pd – Pv) / (1 / Tmn)

IMR = Pd Tmn

at maximal hyperemia…

Derivation of Index of Microcirculatory Resistance (IMR)Derivation of Index of Microcirculatory Resistance (IMR)Derivation of Index of Microcirculatory Resistance (IMR)

Adapted from: Pijls and De Bruyne, Coronary PressureKluwer Academic Publishers, 2000

• Clearly defined normal value• Not affected by resting hemodynamics

• Easy to perform

FFR vs. CFRFFR vs. CFR

IMR

Index of Microcirculatory Resistance (IMR)

Index of Microcirculatory Resistance (IMR)

Measurement of IMRMeasurement of IMR

IMR = 15 UIMR = 15 U

IMRIMR

Derivation of Index of Microcirculatory Resistance (IMR)Derivation of Index of Microcirculatory Resistance (IMR)Derivation of Index of Microcirculatory Resistance (IMR)

0 50 100 150 200 250 300Absolute flow (ml/min)Absolute flow (ml/min)

1 / T

mn

1 / T

mn

0

1.0

2.0

3.0

IMRIMR

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

TMR (mmHg/ml/min)TMR (mmHg/ml/min)

80

70

60

50

40

30

20

10

0

IMR

(mm

Hg·

s)IM

R (m

mH

g·s)

Correlation between IMR and TMR at 24 different combinations of myocardial resistance and epicardial stenosis severity

Correlation between IMR and TMR at 24 different combinations of Correlation between IMR and TMR at 24 different combinations of myocardial resistance and epicardial stenosis severitymyocardial resistance and epicardial stenosis severity

Aarnoudse, Fearon et al. Catheter Cardiovasc Interv. 2004;62(1):56-63.

Reproducibility of IMRReproducibility of IMR

Cor

rela

tion

with

bas

e lin

eC

orre

latio

n w

ith b

ase

line

IMRIMR CFRCFR FFRFFR

1.0

0.8

0.6

0.4

0.2

0.0

Martin et al. Circulation 2006;113;2054-2061

Mean correlation coefficients of IMR, CFR, FFR values comparing baseline measurements with each hemodynamic intervention

Mean correlation coefficients of IMR, CFR, FFR values comparing Mean correlation coefficients of IMR, CFR, FFR values comparing baseline measurements with each hemodynamic interventionbaseline measurements with each hemodynamic intervention

repeat baseline / RV pacing at 110 bpm nitroprusside infusion / dobutamine infusion

repeat baseline / RV pacing at 110 bpm repeat baseline / RV pacing at 110 bpm nitroprusside infusion / dobutamine infusionnitroprusside infusion / dobutamine infusion

Microvascular Integrity in AMIMicrovascular Integrity in AMI

The preservation of the microvascular functions (microvascular integrity) is an important determinants of improvement of the left ventricular function and clinical outcomes after PCI in AMI.

The indices of microvascular integrity were related with clinical outcomes of AMI patients.

Coronary flow reserve, Phasic coronary flow velocity pattern, Microvascular resistance index

: Index of microvascular resistance (IMR) Coronary capillary wedge pressure


Gibson et al. Circulation 2000;101;125-130

Epicardial TIMI 3 flow

9

0

Mor

talit

y (%

)

Epicardial TIMI 2/1/0 flow

TMPG 3 TMPG 0/1/2

9

0

Mor

talit

y (%

)

TMPG 3 TMPG 0/1/2

p = 0.04

4 way p = 0.008

0.7%

4.7%

7.4%

4.7%

6.8%

3.5%

n = 455 n = 294

Relationship of both TIMI grade and TMP grade to 30-day mortalityRelationship of both TIMI grade and TMP grade to 30Relationship of both TIMI grade and TMP grade to 30--day mortalityday mortality


After successful primary PCI for AMI, CFRperformed before discharge was correlated with 201Tl SPECT redistribution patterns and late LV contractility recovery.

F. Beygui et al., J Am Coll Cardiol 2002;40:877

Phasic Coronary flow velocity parameters or patterns is useful in predicting recovery of regional LV function.

Deceleration time of diastolic flow velocity (DDT) > 600msSystolic average peak velocity (SAPV) > 6.5 cm/sec

Akasaka et al. Circulation 1999;100:339


The parameter that correlates best with residual myocardial viability is coronary wedge pressure (Pcw) and this may be a useful index for predicting patient prognosis.

Shimada et al. Heart 2003;89:71–76

In AMI, collateral flow index (CFIp) seems to increase with the severity of microvascular dysfunction. Because higher CFIp was associated with poorer functional recovery, it provides a simple and useful estimate of clinical outcomes in AMI.

Yamamoto et al. J Am Coll Cardiol 2001;38:1383-9

Correlation between IMR and Peak CKCorrelation between IMR and Peak CK

0

1000

2000

3000

4000

5000

6000

7000

0 25 50 75 100 125 150 175

IMR

CK

R=0.54

P <0.001*

R p

CFR .26 0.22

TFG .13 0.50cTFC .09 0.65TMPG .027 0.89ST res .16 0.42

Shah et al. AHA 2006

Peak CK and IMRPeak CK and IMR

0

1000

2000

3000

4000

IMR <35 IMR>35

Peak

CK

P <0.001

1209 ±966

3387 ±1531


FollowFollow--Up Ejection Fraction and IMRUp Ejection Fraction and IMR

0

10

20

30

40

50

60

70

IMR < 35 IMR > 35

Ejec

tion

Frac

tion

(%)

P = 0.01

57.5 ±12

46.1 ±8


FollowFollow--Up Echo Wall Motion Score and IMRUp Echo Wall Motion Score and IMR

18.6

27.5

0

5

10

15

20

25

30

IMR < 35 IMR > 35

Wal

l Mot

ion

Scor

e

P = 0.01


IMR and Microvascular DamagesIMR and Microvascular Damages

TwentyTwenty--nine patients with STEMI treated with primary nine patients with STEMI treated with primary stenting.stenting.

IMR above the median level of 32 had greater peak CK IMR above the median level of 32 had greater peak CK (3128(3128±±1634 vs. 12011634 vs. 1201±±911 IU, p=0.002)911 IU, p=0.002)

IMRIMRrr pp

Peak CKPeak CK 0.540.54 0.0040.004Neutrophil %Neutrophil % 0.520.52 0.010.01

TMPGTMPG --0.420.42 0.030.03CFRCFR --0.430.43 0.030.03cTFCcTFC 0.540.54 0.0040.004

Fearon W et al. J Am Coll Cardiol 2008;51:560–5

ThreeThree--Month Wall MotionMonth Wall MotionScore With Low Versus High IMRScore With Low Versus High IMR


Relation Between Change in WMS and Relation Between Change in WMS and IMRIMR


Correlation between the IMR & percent Correlation between the IMR & percent change in Achange in A--WMSWMS

recovery of LV wall motion (–)

recovery of LV wall motion (+)

CutCut--off value of the IMR for predicting LV off value of the IMR for predicting LV wall motion recoverywall motion recovery

Sensitivity 73%Sensitivity 73%Specificity 100%Specificity 100%

Accuracy 89%Accuracy 89%

IMR and Changes of WMSIMR and Changes of WMS

Comparison of percent change in A-WMS in patientspresenting with an IMR ≤ 33 U and those presenting with

an IMR > 33 U

Comparison of percent change in AComparison of percent change in A--WMS in patientsWMS in patientspresenting with an IMR presenting with an IMR ≤≤ 33 U and those presenting with33 U and those presenting with

an IMR > 33 Uan IMR > 33 U

Correlation between the IMR and RegionalCorrelation between the IMR and RegionalFDG uptake imaged by PETFDG uptake imaged by PET

recovery of LV wall motion (–)recovery of LV wall motion (+)

FDG uptake with an IMR FDG uptake with an IMR ≤≤ 33 U and those 33 U and those presenting with an IMR > 33 Upresenting with an IMR > 33 U

Case 1 : CAGCase 1 : CAG

M/64 STEMI (ant.), onset to balloon time - 120 minM/64 STEMI (ant.), onset to balloon time - 120 min

Pre PCIPre PCI Post PCIPost PCI

Case 1 : IMRCase 1 : IMR

IMR : 11.7 U, CFRthermo : 2.0IMR : 11.7 U, CFRthermo : 2.0M/64 STEMI (ant.)M/64 STEMI (ant.)

Case 1 : FDG PETCase 1 : FDG PET

Myocardial Viability : FDG PET Myocardial Viability : FDG PET Myocardial Viability : FDG PET

FDG Uptake = 70.7%FDG Uptake = 70.7%

Case 1 : EchocardiogramCase 1 : Echocardiogram

After primary PCIAfter primary PCI

66‐‐mo followmo follow‐‐upup

Percent change in APercent change in A‐‐WMS: 42.1%WMS: 42.1%

Case 2 : CAGCase 2 : CAG

M/60 STEMI (ant.), onset to balloon time - 600 minM/60 STEMI (ant.), onset to balloon time - 600 min

Pre PCIPre PCI Post PCIPost PCI

Case 2 : IMRCase 2 : IMR

IMR : 72.3 U, CFRthermo : 1.7 IMR : 72.3 U, CFRthermo : 1.7 M/60 STEMI (ant.)M/60 STEMI (ant.)

Case 2 : FDG PETCase 2 : FDG PET

FDG Uptake = 37.4% FDG Uptake = 37.4%

Myocardial Viability : FDG PET Myocardial Viability : FDG PET Myocardial Viability : FDG PET

Case 2 : EchocardiogramCase 2 : Echocardiogram

After primary PCIAfter primary PCI

66‐‐mo followmo follow‐‐upup

Percent change in APercent change in A‐‐WMS: WMS: ‐‐8.3%8.3%

Advantage of IMRAdvantage of IMR

Highly reproducible index which is not affected hemodynamic conditons

IMR has good correlation with absolute coronary blood flow and true microvascular reistance

Limitations of IMRLimitations of IMR

• Lack of optimal cutoff value about microvascular dysfunction

• Additional procedure for inducing hyperemia• No large randomized clinical data

ConclusionsConclusions

IMR, a novel index representing the microvascular integrity, is a reliable parameter for the invasive, on-site assessment of myocardial viability after

primary PCI in AMI.

IMR, a novel index representing the microvascular IMR, a novel index representing the microvascular integrity, is a reliable parameter for the invasive, integrity, is a reliable parameter for the invasive, onon--site assessment of myocardial viability after site assessment of myocardial viability after

primary PCI in AMI.primary PCI in AMI.

What do interventionists need in clinical practice?

1) Epicardial Vessel FFR

2) Microvasculature IMR!!

Research Fellow 2009Research Fellow 2009

Dr Ramasamy, Dr Poddar from India RN, Seo Young ParkKorean Research Fellow, Ji Young Park

Dr Wang from Tianjin, China

Thank You for Your Attention!! Thank You for Your Attention!!

Korea University Guro Hospital

Korea University Guro Hospital

Thank you for your attention !Thank you for your attention !Thank you for your attention !

Documents

Value of Index of Microvascular Resistance (IMR) in ... · Value of Index of Microvascular Resistance (IMR) in Microvascular Integrity Seung-Woon Rha, Korea University Guro Hospital,