Comparable clinical outcomes of radial artery grafts versus right internal mammary artery grafts during CABG, suggests study

The researchers revealed that RIMA and RA conduits for coronary artery bypass grafting (CABG) were associated with comparable 5-year major adverse cardiac and cerebrovascular events (MACCE), immediate postoperative complications, and 5-year survival after propensity score matching (PSM).

CABG remains the gold standard for treating obstructive atheromatous disease within the coronary arteries, with excellent short- and long-term postoperative outcomes. A left internal mammary artery (LIMA) graft is standardly used in revascularization of the left anterior descending coronary artery, however, there has been no clarity on the consensus on the best secondary conduit for additional grafting.

Eishan Ashwat, Division of Cardiac Surgery, Department of Cardiothoracic Surgery, University of Pittsburgh, and colleagues aimed to compare the clinical outcomes of radial artery grafts during CABG to those of the right internal mammary artery grafts.

For this purpose, they conducted a retrospective, single-institution cohort study of isolated CABG with multiple grafts between 2010-2022. PSM was performed using a 1:1 match ratio to balance graft cohorts.

Long-term postoperative survival was compared among RA and RIMA groups. Similarly, MACCE were compared among both cohorts, with MACCE comprising myocardial infarction (MI), death, stroke, and coronary revascularization. Kaplan-Meier estimation was performed for mortality, while cumulative incidence estimation was used for MACCE.

8,774 patients underwent CABG. Of those, 1,674 patients who underwent multi-arterial CABG were included in the analysis. 326 patients received RA grafts, and 1,348 received RIMA grafts. 

The study led to the following findings:

• PSM yielded a cohort of 323 RA patients and 323 RIMA patients.
• After matching, groups were well-balanced across all baseline variables.
• There were no significant differences in immediate postoperative complications or long-term survival, with 5-year survival estimates of 89.5% for the RA group versus 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 versus 24.1% in the RIMA group), especially after 1-year follow-up (21.6% in the RA group versus 15.1% in the RIMA group).
• For RA patients, there were higher rates of repeat revascularization in the 5-year postoperative period (14.7% in the RA group versus 5.3% in the RIMA group), particularly in the territory revascularized by the RA during the index operation (45.7% in the RA group versus 10.3% in the RIMA group).

"The findings showed that RA and RIMA secondary conduits for CABG were associated with comparable deep sternal wound infection, operative mortality, 5-year survival, and 5-year MACCE," the researchers wrote.

Reference:

Ashwat, E., Brown, J. A., Yousef, S., Ahmad, D., Wang, Y., Thoma, F. W., Serna-Gallegos, D., Yoon, P., West, D., Chu, D., Bonatti, J., Kaczorowski, D., & Sultan, I. (2024). Radial Artery versus Right Internal Mammary Artery as a Second Conduit during Coronary Artery Bypass Grafting. American Heart Journal. https://doi.org/10.1016/j.ahj.2024.01.006