Coronary artery disease remains the leading cause of death worldwide, and coronary artery bypass grafting (CABG) continues to play a central role in the treatment of advanced multivessel disease. For decades, surgeons have debated whether bypass surgery performed with cardiopulmonary bypass (on-pump CABG or ONCAB) offers superior long-term outcomes compared with surgery performed on the beating heart without cardiopulmonary bypass (off-pump CABG or OPCAB). While previous randomized trials and meta-analyses have provided conflicting results, very-long-term follow-up data extending beyond 10 years have remained limited.
In this study, investigators from Finland examined long-term survival and cardiovascular mortality among patients undergoing isolated primary CABG at a single cardiac surgery center between 1999 and 2016. The study included 2,935 patients, of whom 2,496 underwent conventional ONCAB and 439 underwent OPCAB. To minimize selection bias and account for differences in patient characteristics, the authors used propensity score matching to create a balanced cohort consisting of 402 OPCAB patients matched to 804 ONCAB patients.
The primary objective was to determine whether the choice of operative technique influenced overall survival over an extended follow-up period. Patients were followed through January 2024, providing a median follow-up of more than 12 years and a maximum follow-up approaching 24 years. This exceptionally long observation period represents one of the major strengths of the study.
The analysis demonstrated remarkably similar outcomes between the two surgical approaches. Median survival was 12.4 years in the ONCAB group and 12.6 years in the OPCAB group. Statistical analysis revealed no significant difference in all-cause mortality between groups, with a hazard ratio of 0.95 favoring neither strategy. Kaplan-Meier survival curves remained closely aligned throughout follow-up, further supporting equivalent long-term survival.
Cardiovascular mortality also showed no significant difference between groups. At 10 years, the cumulative incidence of cardiovascular death was approximately 18% in ONCAB patients and 19% in OPCAB patients. Competing-risk analyses confirmed that operative technique did not significantly influence cardiovascular mortality over time.
Although survival outcomes were similar, several procedural differences were observed. Patients undergoing ONCAB received more distal anastomoses and more venous and arterial grafts than OPCAB patients. This finding is consistent with prior studies suggesting that complete revascularization can be more technically challenging during beating-heart surgery. Despite these differences, the lower number of grafts in the OPCAB group did not translate into worse long-term survival.
Early postoperative outcomes were likewise comparable. Thirty-day mortality remained low in both groups, and no significant differences were observed in rates of stroke, myocardial infarction, atrial fibrillation, deep sternal wound infection, dialysis, reoperation, or intra-aortic balloon pump use. Biomarkers including troponin and creatinine levels were somewhat higher after ONCAB, reflecting the physiologic impact of cardiopulmonary bypass, but these differences did not appear to influence long-term outcomes.
The study contributes important evidence to a long-running surgical debate. Off-pump surgery was originally developed to avoid the inflammatory response, embolic complications, and organ dysfunction associated with cardiopulmonary bypass. Critics have argued that the technique may compromise graft quality or completeness of revascularization, potentially leading to inferior long-term outcomes. The current findings suggest that when performed by experienced surgeons and in appropriately selected patients, OPCAB can achieve survival comparable to traditional on-pump surgery.
The authors emphasize that patient selection remains critical. Current guidelines do not recommend one technique universally over the other. Instead, factors such as aortic calcification, comorbidities, coronary anatomy, and surgeon expertise should guide operative planning. Their results support a Heart Team approach in which surgical strategy is individualized rather than standardized.
Several limitations should be considered. The study was retrospective and observational, making residual confounding unavoidable despite propensity matching. Surgical practices evolved during the lengthy study period, and data regarding coronary lesion complexity and completeness of revascularization were limited. Nonetheless, the large cohort, prospectively maintained surgical database, and comprehensive national mortality follow-up strengthen the reliability of the findings.
Overall, this study provides compelling evidence that on-pump and off-pump CABG offer comparable long-term survival and cardiovascular mortality when performed in a contemporary cardiac surgery practice. These results support continued use of both techniques and reinforce the importance of tailoring operative strategy to individual patient characteristics and surgical expertise.
