Outcomes of on-pump versus off-pump coronary artery bypass graft surgery in the high risk (AusSCORE > 5)

Background: Coronary artery bypass graft surgery (CABG) has been established as the preferred intervention for coronary revascularisation in the high-risk population. Off-pump coronary artery bypass (OPCAB) may further reduce mortality and morbidity in this population subgroup. This study presents the largest series of high-risk (AusSCORE > 5) OPCAB patients in Australia and New Zealand. Methods: We reviewed the Australian and New Zealand Society of Cardiac and Thoracic Surgeons' (ANZSCTS) database for high-risk patients (n=7822) undergoing isolated CABG surgery and compared the on-pump coronary artery bypass (ONCAB) (n=7277) with the OPCAB (n=545) technique. Preoperative and intraoperative risk factors, and postoperative outcomes were analysed. Survival analysis was performed after cross-matching the database with the national death registry to identify long-term mortality. Results: The ONCAB and OPCAB groups had similar risk profiles based on the AusSCORE. Thirty-day mortality (ONCAB vs OPCAB 3.9% vs 2.4%, p=0.067) and stroke (ONCAB vs OPCAB 2.4% vs 1.3%, p=0.104) were similar between the two groups. OPCAB patients received fewer distal anastomoses than ONCAB patients (2.5±1.2 vs 3.3±1.0, p<0.001). The rates of new postoperative atrial arrhythmia (28.3% vs 33.3%, p=0.017) and blood transfusion requirements (52.1% vs 59.5%, p=0.001) were lower in the OPCAB group, while duration of ICU stay in hours (97.4±187.8 vs 70.2±152.8, p<0.001) was longer. There was a non-significant trend towards improved 10-year survival in OPCAB patients (74.7% vs. 71.7%, p=0.133). Conclusions: In the high-risk population, CABG surgery has a low rate of mortality and morbidity suggesting that surgery is a safe option for coronary revascularisation. OPCAB reduces postoperative morbidity and is a safe procedure for 30-day mortality, stroke and long-term survival in high-risk patients.