Off-pump versus On-pump Coronary Artery Bypass Grafting in Patients With Severe Left Ventricular Dysfunction

Abstract

Background: The comparative effectiveness of off-pump (OPCAB) and on-pump coronary artery bypass grafting (ONCAB) in severe left ventricular dysfunction remains uncertain. Methods: We conducted a retrospective institutional cohort study of isolated CABG procedures performed from 1996 to 2023. Registry-coded severe dysfunction comprised left ventricular ejection fraction below 30% or the legacy category of 21–30%. The primary outcomes were 30-day mortality and long-term all-cause mortality. Propensity-score overlap weighting included calendar year and baseline clinical characteristics. Restricted mean survival and time-stratified models were used because proportional hazards were not satisfied. Results: Of 557 eligible operations with known pump status, 541 had usable survival time (301 ONCAB; 240 OPCAB); 140 deaths occurred. After weighting, all assessed covariates were balanced (maximum absolute standardized mean difference, 0.001). Weighted 30-day mortality was 8.7% after ONCAB and 3.8% after OPCAB (odds ratio 0.42, 95% confidence interval 0.13–1.34; p=0.144). Long-term mortality did not differ (hazard ratio 0.96, 95% confidence interval 0.67–1.37; p=0.819). Fifteen-year restricted mean survival differed by 0.33 years in favor of OPCAB. The proportional-hazards assumption was violated; neither the 0–5-year nor post-5-year estimate was significant. Conclusions: In this long-running, expertise-based cohort, OPCAB was associated with a numerically lower early mortality rate but no statistically reliable early or long-term advantage after calendar-era and baseline adjustment. The findings support equipoise and careful strategy selection rather than preferential use of either technique.