Time-Varying Association of the Second Internal Thoracic Artery with Long-Term Survival after Coronary Artery Bypass Grafting

Background The survival advantages of bilateral internal thoracic artery (BITA) grafts in coronary artery bypass grafting (CABG) surgery remain unclear. Therefore, this study aims to systematically evaluate the time-dependent influence of BITA on long-term survival in elective CABG patients presenting with stable multivessel coronary artery disease. Methods Data from 3,693 patients undergoing isolated CABG with single internal thoracic artery (SITA) or BITA, with or without additional vein grafts, between 2002 and 2012 were retrospectively analyzed. The entire cohort was divided into BITA and SITA groups (830 vs. 2,863 patients). A 1:3 propensity score matching was performed. Subsequent analysis of a subgroup meeting Randomized comparison of the clinical Outcome of single versus Multiple Arterial grafts (ROMA) trial criteria ( n = 1,339) followed a 1:1 matching. Differences in restricted mean survival time (RMST) estimates were used to assess the time-varying association of BITA with long-term survival. Results In-hospital mortality (SITA 1.8% vs. BITA 1.1%, p = 0.2) and major postoperative complications were similar between the matched groups. However, long-term survival was significantly higher in BITA patients for the matched whole cohort (15-year survival: 64 vs. 51%, respectively; p < 0.001) and the ROMA-like population (76 vs. 60%, respectively; p < 0.001). RMST demonstrated an incremental survival advantage of BITA over SITA grafting over time for both the whole and ROMA-like populations (0.1, 0.5, and 1.1 years, and 0.1, 0.4, and 1.0 years at 5-, 10-, and 15-year follow-up, respectively) Conclusion BITA grafting is safe and associated with superior long-term survival compared with SITA and vein grafts, with benefits extending beyond 5 years for the entire cohort and beyond 10 years for ROMA criteria patients.