Coronary artery bypass surgery improves restricted mean survival time in patients with ischemic cardiomyopathy

Clinical trials commonly use Cox proportional hazards models, which may be inaccurate when evaluating procedural interventions. Restricted mean survival time (RMST) is an alternative outcome measure that quantifies treatment effects without assuming proportional hazards. We determined outcomes based on RMST in the Surgical Treatment for Ischemic Heart Failure (STICH) trial, an international multicenter randomized clinical trial comparing coronary artery bypass grafting (CABG) plus optimal medical therapy to optimal medical therapy alone in patients with ischemic cardiomyopathy. For the primary endpoint of all-cause mortality, CABG plus medical therapy was superior to medical therapy alone at 10 years of follow up when using measures of RMST. In subgroup analyses evaluating all-cause mortality, there was a greater beneficial effect of CABG for racial/ethnic minorities vs. white patients. These findings reinforce the benefit of CABG and can be used to help quantify anticipated outcomes for patients with ischemic cardiomyopathy. • Clinical trials often compare therapies using Cox proportional hazards models, but proportional hazards may not be present. • Restricted mean survival time (RMST) compares outcomes between groups without assuming proportional hazards. • The STICH trial randomized patients with ischemic cardiomyopathy to CABG with medical therapy or medical therapy alone. • CABG with medical therapy had lowerall-cause mortality than medical therapy alone when using measures of RMST. • Clinical trials should consider reporting RMST measures routinely, particularly when proportional hazards are uncertain.