Predictive value of myocardial viability on the volume change of left ventricle after coronary artery bypass graft

Objective: To evaluate the predictive role of myocardial viability assessed by ⁹⁹Tc^m-MIBI GSMPI and ¹⁸F-FDG PET on the volume change of the left ventricle (LV) after coronary artery bypass graft (CABG) operation. Methods: From December 2013 to December 2014, 39 patients (37 males, 2 females; average age (64 ± 9) years) with ischemic cardiomyopathy planned for surgical revascularization in the Third Affiliated Hospital of Soochow University were prospectively recruited. All patients underwent ⁹⁹Tc^m-MIBI GSMPI and myocardial ¹⁸F-FDG PET to assess myocardial viability preoperatively and GSMPI to assess myocardial perfusion 3-6 months after CABG. Reduction of LV volume ≥ 10% was considered significant. Patients were divided into two groups based on the reduction of LV volume, and the clinical data were compared between the two groups including gender, age, BMI, history of hypertension, diabetes, hyperlipidemia, angina pectoris, CCS classification for angina pectoris, NYHA classification for functional status, EDV, ESV, LVEF, preoperative creatinine, Gensini score, the number of viable myocardium, scar and normal myocardium and follow-up duration, by independent-sample t test, χ² test and Mann-Whitney test. Multivariate logistic regression analysis was performed to determine the factors to predict reduction of LV volume after revascularization. ROC curve analysis was performed to determine the cut off number of hibernating segments for reduction of LV volume after revascularization. Results: The number of viable segments in the reduced group (n = 26) was significantly higher than that in the non-reduced group ((n = 13; 4.5 ± 2.8 vs 2.4 ± 1.5; t = -3.011, P < 0.05) and the number of scarring segments in the reduced group was significantly less than that in the non-reduced group (0(0, 1.0) and 1.0(0, 2.0); z = -2.084, P < 0.05). The clinical data between the 2 groups were not significantly different(i: -0.253 to 1.522, χ²: -1.014 to 1.251, all P > 0.05). The number of viable segments was directly related to reduction of LV volume after revascularization (odds ratio(OR) = 2.462, P < 0.05). ROC curve analysis revealed that 3 viable segments yielded the highest sensitivity, specificity and accuracy (all were 76.92%; 10/13, 20/26, 30/39) for predicting reduction of LV volume, and the AUC was 0.743. The rate of LV volume reduction in patients with more than 3 viable segments (86.96%, 20/23) was higher than that of patients with less than 3 viable segments (37.50%, 6/16; χ² = 10.39, P < 0.01). Conclusions: The reduced group has more viable segments and less scarring segments than the non-reduced group. The number of viable segments is directly related to LV volume reduction after revascularization. The presence of more than three mismatched segments on GSMPI and myocardial ¹⁸F-FDG PET in patients with ischemic cardiomyopathy before CABG is an independent predictor of LV volume reduction. (authors)