10-year outcomes post coronary artery bypass grafting in Asian patients with ischemic cardiomyopathy: a comprehensive analysis of survival and cardiac performance

BACKGROUND: Coronary artery bypass grafting (CABG) is the standard of care for patients with ischemic cardiomyopathy (ICM). Despite recent evidence supporting the role of CABG, long term outcomes for patients with ICM remain poor and 10-year results post CABG in ICM patients are under-reported, especially among Asians. Uncertainty on whether CABG improves cardiac performance and survival in the long term remains. In this study, we aim to analyze 10-year results concerning cardiac performance and survival post CABG in Asian patients with left ventricular ejection fraction (LVEF) ≤35% and predominant heart failure symptoms, and identify perioperative risk factors affecting long term survival and cardiac function. METHODS: Thirty-six patients with LVEF <35% who had CABG performed between the year 2006-2009 were selected from local hospital records for retrospective analysis. Outcomes of interest included post-operative cardiac symptoms, LVEF & 10-year all-cause and cardiac-event free survival. Survival analysis was performed using Kaplan Meier analysis, and predictive factors were identified with log- rank test and logistic regression analysis. RESULTS: The mean age of the cohort was 62.9±9.9 years. Operative mortality within 30 days was 5.6%. The 10-year all-cause mortality rate was 55.6%. The mean duration of survival was 105.9±8.3 months. Of the patients who did not survive till 10 years, 65.0% died of cardiac-related causes, with non-ST elevation myocardial infarction being the commonest cause. CABG improved LVEF (24.9% to 32.2%; P<0.001) and 66.7% of patients remained with impaired LVEF ≤35% post CABG. Post op NYHA class 3-4 symptoms (OR: 6.3; P=0.012) was the only predictive factor for 10 year all-cause mortality and post op LVEF improvement ≥5% (OR: 5.8; 95% CI, 1.1-29.9; P=0.036) was associated with improvement in NYHA class. Completeness of revascularization and viability of myocardium were not predictive of survival or changes in LVEF or NYHA class. CONCLUSIONS: The 10-year survival rates of Asian patients with ICM were similarly disappointing as its counterparts in the west. A majority of patients still suffered from cardiac-event related deaths. Post CABG NYHA class was found to be important in determining success and adequacy of treatment in patients with ICM and improvement in LVEF ≥5% was predictive of improvement of symptoms. Neither completeness of revascularization or presence of myocardial viability had any impact on survival in our patient cohort.