Effect of Myocardial Viability Assessed by Cardiac Magnetic Resonance on Survival in Patients With Severe Left Ventricular Dysfunction.

Background: Myocardial viability assessment in revascularization of ischemic heart failure remains controversial. This study evaluated the prognostic utility of cardiac magnetic resonance (CMR) late gadolinium enhancement (LGE) in ischemic heart failure. Methods and Results: This study retrospectively analyzed subjects with ischemic heart failure and left ventricular ejection fraction (LVEF) ≤35%, who underwent CMR at a single center in 2004-2014 before undergoing coronary artery bypass grafting (CABG) or optimal medical therapy (OMT). Analyses were stratified by treatment. Myocardial segments were deemed non-viable if LGE exceeded 50% wall thickness. Overall and anterior viability were assessed. Outcomes were all-cause mortality, cardiovascular (CV) mortality and major adverse CV events. Among 165 subjects (mean (±SD) age 57.5±8.5 years, 152 males), 79 underwent CABG and 86 received OMT. A greater number of non-viable segments was significantly associated with higher all-cause and CV mortality in the CABG group (adjusted hazard ratios 1.17 [95% confidence interval {CI} 1.01-1.37; P=0.04] and 1.25 [95% CI 1.01-1.56; P=0.045], respectively), but not in the OMT (P>0.05) group. Anterior wall viability did not affect outcomes. Conclusions: The extent of myocardial viability assessed by LGE appeared to identify patients with a differential survival benefit from CABG in this retrospective, small cohort study. These findings raise interesting hypotheses that need to be validated in larger prospective studies.