© 2014 The American Association for Thoracic Surgery. Objectives:We conducted a multicenter observational cohort study of the effect of completeness of revascularization on long-term survival after coronary artery bypass grafting. We also investigated the impact of age and off-pump surgery.Methods: The Veterans Affairs Continuous Improvement in Cardiac Surgery Program was used to identify all patients (N = 41,139) with left main and 3-vessel coronary artery disease who underwent nonemergency coronary artery bypass grafting from October 1997 to April 2011. The primary outcome measure, all-cause mortality, was compared between patients with complete revascularization and patients with incomplete revascularization. Survival functions were estimated with the Kaplan-Meier method and compared by using the log-rank test. Propensity scores calculated for each patient were used to match 5509 patients undergoing complete revascularization to 5509 patients undergoing incomplete revascularization. A subgroup analysis was performed in patients aged at least 70 years and patients who underwent off-pump coronary artery bypass grafting.Results: In the unmatched groups, several risk factors were more common in the incomplete revascularization group, as was off-pump coronary artery bypass grafting. In the matched groups, risk-adjusted mortality was higher in the incomplete revascularization group than in the complete revascularization group at 1 year (6.96% vs 5.97%; risk ratio [RR], 1.17; 95% confidence interval [CI], 1.01-1.34), 5 years (18.50% vs 15.96%; RR, 1.16; 95% CI, 1.07-1.26), and 10 years (32.12% vs 27.40%; RR, 1.17; 95% CI, 1.11-1.24), with an overall hazard ratio of 1.18 (95%CI, 1.09-1.28; -Rfpag < .0001). The hazard ratio for patients aged 70 years or more was 1.125 (95% CI, 1.001-1.263; P = .048). The hazard ratio was 1.47 (95% CI, 1.303-1.655) for the unmatched off-pump coronary artery bypass grafting group and 1.156 (95% CI, 1.000-1.335) for the matched off-pump coronary artery bypass grafting group.Conclusions: Incomplete revascularization is associated with decreased long-term survival, even in elderly patients. Surgeons should consider these findings when choosing a revascularization strategy, particularly if off-pump coronary artery bypass grafting is contemplated.