The effect of viable myocardium on left ventricular function after elective revascularization in patients with myocardial infarction by dual-isotope simultaneous acquisition myocardial perfusion-metabolic imaging

Objective: To evaluate the effect of myocardial viability on left ventricular function after elective revascularization in patients with myocardial infarction by 99Tcm-MIBI and 18F-FDG dual-isotope simultaneous acquisition (DISA) myocardial perfusion-metabolic imaging. Methods: Ninety-one patients clinically confirmed of myocardial infarction underwent DISA imaging. Based on the results of echocardiography, the patients were divided into heart failure group (group A) and normal cardiac function group (group B). After PCI, left ventricular function was measured by echocardiography in 1, 3 and 6 months. The t-test and χ2-test were used to compare the difference between the two groups using SPSS 13.0. Results: The average number of diseased segments by myocardial perfusion imaging was 9.8±3.5 and 5.4±2.6 in groups A and B, respectively (t=6.87, P<0.01). The average number of diseased segments by myocardial metabolic imaging was 7.5±3.4 and 4.6±2.8 in groups A and B, respectively (t=4.46, P<0.01). There were 173 segments with viable myocardium (173/458: 37.8%) in group A and 188 segments with viable myocardium (188/307: 61.2%) in group B (χ2=40.61, P<0.001). The summed perfusion score (SPS), summed metabolism score (SMS) and summed difference score (SDS=SMS-SPS) were 28.43±11.86 vs 21.36±9.54, 20.17±8.52 vs 15.19±5.74 and 0.39±3.17 vs -12.72±4.55, respectively in groups A and B (t=3.15, P<0.01; t=3.32, P<0.01; t=15.59, P<0.01). The mean change of LVEF (ΔLVEF) and the mean change of left ventricular end-diastole dimension (ΔLVEDd) of the patients with more than 4 viable myocardial segments in group A were significantly more than those in group B((12.81±2.62)% vs (5.90±1.91)%, t=16.33, P<0.001; (-13.13±4.20) mm vs (-7.75±2.31) mm, t=6.86, P<0.001). However, the ΔLVEF and ΔLVEDd of the patients with less than 4 viable myocardial segments in group A were significantly less than those in group B (t=3.25, P<0.01; t=4.92, P<0.001). Conclusion: The amount of viable myocardium in infarct myocardium is an important factor for left ventricular function recovery after elective revascularization. (authors)