Radial Artery versus Right Internal Mammary Artery as a Second Conduit during Coronary Artery Bypass Grafting.

OBJECTIVE: To compare the clinical outcomes of radial artery (RA) grafts during CABG to those of right internal mammary artery (RIMA) grafts.

METHODS: This was a retrospective, single-institution cohort study of isolated CABG with multiple grafts between 2010-2022. To balance graft cohorts, propensity score matching (PSM) was performed using a 1:1 match ratio. Long-term postoperative survival was compared among RA and RIMA groups. Similarly, major adverse cardiac and cerebrovascular events (MACCE) were compared among both cohorts, with MACCE comprising death, myocardial infarction (MI), coronary revascularization, and stroke. Kaplan-Meier estimation was performed for mortality, while cumulative incidence estimation was utilized for MACCE.

RESULTS: A total of 8,774 patients underwent CABG. Of those, 1,674 (19.1%) patients who underwent multi-arterial CABG were included in this analysis. 326 (19.5%) patients received RA grafts and 1,348 (80.5%) received RIMA grafts. PSM yielded a cohort of 323 RA patients and 323 RIMA patients. After matching, groups were well-balanced across all baseline variables. No significant differences were observed in immediate postoperative complications or long-term survival, with 5-year survival estimates of 89.5% for the RA group vs 90.1% for the RIMA group. There was a non-significant trend toward a higher incidence of MACCE at 5 years in the RA group compared to the RIMA group (31.3% in the RA group vs. 24.1% in the RIMA group), especially after 1-year follow-up (21.6% in the RA group vs. 15.1% in the RIMA group). Specifically, for RA patients, there were higher rates of repeat revascularization in the 5-year postoperative period (14.7% in the RA group vs. 5.3% in the RIMA group), particularly in the territory revascularized by the RA during the index operation (45.7% in the RA group vs. 10.3% in the RIMA group).

CONCLUSION: Overall, RA and RIMA secondary conduits for CABG were associated with comparable immediate postoperative complications, 5-year MACCE, and 5-year survival after PSM. RA grafting was associated with significantly higher rates of repeat coronary revascularization at 5 years, specifically in the territory revascularized by the RA during the index operation.