Korean Circ J.  2007 Jul;37(7):318-326. 10.4070/kcj.2007.37.7.318.

A Novel Index of Microcirculatory Resistance for Invasively Assessing Myocardial Viability after Primary Angioplasty for Treating Acute Myocardial Infarction: Comparison with FDG-PET Imaging

• Lim HS
• Tahk SJ
• Yoon MH
• Woo SI
• Choi WJ
• Hwang JW
• Li DH
• Seo KW
• Park JS
• Kim JW
• Kang SJ
• Choi BJ
• Choi SY
• Hwang GS
• Shin JH

• KMID: 2227059
• DOI: http://doi.org/10.4070/kcj.2007.37.7.318

Abstract

BACKGROUND AND OBJECTIVES: The state of the coronary microcirculation is an important determinant of the myocardial viability and clinical outcomes for patients suffering with acute myocardial infarction (AMI). However, there are scant comparative studies on the most reliable invasive, on-site measurement for assessing the microvascular integrity and myocardial viability in AMI patients. The aim of this study is to evaluate the usefulness of a novel index of microcirculatory resistance (IMR) and the coronary physiologic parameters for predicting the myocardial viability after primary percutaneous coronary intervention (PCI) in AMI patients.
SUBJECTS AND METHODS
Twenty-four patients (21 males, mean age: 55+/-11 years) underwent primary PCI for AMI (LAD: 17, RCA: 6, LCX: 1) were enrolled. After successful PCI, using a pressure-temperature sensor-tipped coronary wire, the thermodilution-derived CFR (CFRthermo) and coronary wedge pressure (Pcw) were measured and the ratio of the Pcw and the mean aortic pressure (Pcw/Pa) was calculated, along with the IMR, which was defined as the distal coronary pressure divided by the inverse of the hyperemic mean transit time. 18F-fluorodeoxyglucose (FDG) PET was performed after primary PCI at 7 days post-AMI to evaluate the myocardial viability by the regional percentage of FDG uptake in the infarct-related segments.
RESULTS
There were good correlations between all the coronary pressure measurements and the regional FDG uptake (CFRthermo, r=0.454, p=0.026; Pcw, r=-0.407, p=0.048; Pcw/Pa, r=-0.480, p=0.018; IMR, r=-0.696, p<0.001, respectively). Multiple logistic regression analysis demonstrated that the IMR was an adjusted predictor for myocardial viability as defined by the 50% FDG-PET threshold value among all the coronary pressure measurements (OR=0.884, p=0.021). The cut-off value of IMR for predicting myocardial viability was 22 U (a sensitivity of 82%, a specificity of 85% and an accuracy of 85%).
CONCLUSIONS
Intracoronary pressure wire-based indexes are useful for on-site assessment of myocardial viability after primary PCI. IMR is a novel index that represents the microvascular integrity, and it is a better predictor of myocardial damage than the current techniques for evaluating the microvasculature after primary PCI.

Keyword

Myocardial infarction; Pressure; Viability; Positron-emmission tomography

MeSH Terms

Angioplasty*
Arterial Pressure
Humans
Logistic Models
Male
Microcirculation
Microvessels
Myocardial Infarction*
Percutaneous Coronary Intervention
Pulmonary Wedge Pressure
Sensitivity and Specificity

Figure

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  Fig. 1. Diagrammatic representation of the 20-segment model of FDG-PET imaging: for regional analysis, the anterior region is defined by segments 1,7 and 13, the septal region by segments 2, 3, 8, 9, 14 and 15, the inferior region by segments 4, 10 and 16, the lateral region by segments 5, 6, 11, 12, 17 and 18 and the apex by segments 19 and 20. FDG: 18 F-fluorodeoxyglucose, PET: positron emission tomography.

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  Fig. 2. The relationship between intracoronary pressure wire measurements and FDG-uptake. Regional FDG uptake is plotted against coronary wedge pressure (P cw), P cw to mean aortic pressure (P a) ratio (P cw/P a), thermodilution coronary flow reserve (CFR thermo) and index of microcirculatory resistance (IMR). Correlation coefficients are shown. FDG: 18 F-fluorodeoxyglucose.

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  Fig. 3. Comparison of receiver operating characteristic (ROC) curve analysis of physiologic parameters using intracoronary pressure wire for the prediction of myocardial viability as defined by the 50% FDG-PET threshold value. The best cut-off value (BVC) and the area under ROC curve (AUC) of each parameter were shown.

Reference

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