Complex coronary anatomy in coronary artery bypass graft surgery: impact of complex coronary anatomy in modern bypass surgery? Lessons learned from the SYNTAX trial after two years.

OBJECTIVE: SYNTAX study compares outcomes of coronary artery bypass grafting with percutaneous coronary intervention in patients with 3-vessel and/or left main disease. Complexity of coronary artery disease was quantified by the SYNTAX score, which combines anatomic characteristics of each significant lesion. This study aims to clarify whether SYNTAX score affects the outcome of bypass grafting as defined by major adverse cerebrovascular and cardiac events (MACCE) and its components over a 2-year follow-up period. METHODS: Of the 3075 patients enrolled in SYNTAX, 1541 underwent coronary artery bypass grafting (897 randomized controlled trial patients, and 644 registry patients). All patients undergoing bypass grafting were stratified according to their SYNTAX score into 3 tertiles: low (0-22), intermediate (22-32), and high (≥33) complexity. Clinical outcomes up to 2 years after allocation were determined for each group and further risk factor analysis was performed. RESULTS: Registry patients had more complex disease than those in the randomized controlled trial (SYNTAX score: registry 37.8 ± 13.3 vs randomized 29.1 ± 11.4; P < .001). At 30 days, overall coronary bypass mortality was 0.9% (registry 0.6% vs randomized 1.2%). MACCE rate at 30 days was 4.4% (registry 3.4% vs randomized 5.2%). SYNTAX score did not significantly affect overall 2-year MACCE rate of 15.6% for low, 14.3% for medium, and 15.4% for high SYNTAX scores. Compared with randomized patients, registry patients had a lower rate of overall MACCE rate (registry 13.0% vs randomized 16.7%; P = .046) and repeat revascularization (4.7% vs 8.6%; P = .003), whereas other event rates were comparable. Risk factor analysis revealed left main disease (P = .049) and incomplete revascularization (P = .005) as predictive for adverse 2-year outcomes. CONCLUSIONS: The outcome of coronary artery bypass grafting was excellent and independent from the SYNTAX score. Incomplete revascularization rather than degree of coronary complexity adversely affects late outcomes of coronary bypass.