Recent studies have once again brought into question the long term survival following off-pump coronary artery bypass grafting (OPCAB) compared to conventional on-pump coronary artery bypass grafting surgery (ONCAB). The primary aim of this study is to compare the long term risk-adjusted survival rates in patients undergoing coronary artery bypass grafting (CABG) using these two techniques.
We undertook a propensity score matched analysis of 10,293 patients who underwent CABG between 2000 – 2016 at our single institution. A logistic regression model was fitted using 14 covariates and their two-way interactions to calculate an estimated propensity score (AUC 0.69), from which 1:1 nearest neighbor matching was performed. Survival was assessed using the Kaplan-Meier method and log-rank test.
Of the total cohort, 8,319 patients had ONCAB and 1,974 had OPCAB. Prior to matching the OPCAB group had marginally higher EuroSCORE (3.7 ± 2.7 vs 3.5 ± 3, median and IQR 3[2, 5] vs 3[2, 5], p=0.016) and significantly lower average number of grafts per patient (2.39 ± 0.72 vs 2.75 ± 0.48, p<0.001. Post matching distributions between OPCAB and ONCAB showed a substantial improvement in balance in pre-operative patient characteristics. The two surgery groups differed significantly in survival (p<0.001). OPCAB demonstrated improved long-term survival at both 10 years (84.8%, 95% CI: (82.7, 86.9) vs 75.8%, 95% CI: (73.4%, 78.2%)) and 15 years (65.4%, 95% CI: (61.4%, 69.6%) vs 58.5%, 95% CI (54.9%, 62.3%)). Results of sensitivity analysis for 1:2 and 1:3 matched data were in concordance with these findings of survival.
At our institution, selected patients undergoing OPCAB have lower in-hospital morbidity and improved long term survival when compared to a matched population of ONCAB patients.