Off- vs. On-Pump Coronary Artery Bypass Grafting Long-Term Survival is Driven by Incompleteness of Revascularisation

Background: Off-pump coronary artery bypass grafting (CABG) negates the requirement for extracorporeal circulation used with the traditional on-pump approach. However, off-pump CABG is technically more challenging and may theoretically lead to less complete revascularisation. Recent data suggests a prognostic benefit for traditional on-pump CABG, but the mechanism for this remains unclear. We hypothesised that the inferior outcomes with off-pump CABG could be driven by the need for repeat revascularisation, with this benefit only becoming clear at long-term follow-up. We therefore evaluated short, medium and long-term outcomes of patients undergoing revascularisation with on vs. off-pump CABG. Methods: Electronic databases were searched to identify suitable randomised controlled trials enrolling ≥100 patients in each arm. Clinical outcomes were extracted at 30-days, 12-months or >4 years. The primary outcome was long-term all-cause death, while secondary outcomes included 30-day, 12-month and >4-year cardiac death, stroke, myocardial infarction or revascularisation. Results: Thirteen studies comprising 13,234 patients were included. Off-pump CABG was associated with an increased risk of all-cause death (Odds Ratio (OR) 1.18, 95% confidence interval (CI) 1.02–1.32, p = 0.01) and repeat bypass surgery (OR 2.57, 95%CI 1.23–5.39, p = 0.01) at long-term follow-up. A significant, increased requirement for revascularisation in off-pump was seen at 12-month follow-up (OR 1.59, 95%CI 1.09–2.33, p = 0.02). No differences were noted between groups at 30-days, 12-months and >4 years for myocardial infarction or stroke. Conclusions: Off-pump CABG is associated with significantly higher rates of all-cause mortality rate at long-term follow-up. These outcomes demonstrate a temporal relationship that may be driven by a greater requirement for repeat revascularisation at 1- and 5-year follow-up. Trial registration: CRD42018102019.