Equipoise between radial artery and right internal thoracic artery as the second arterial conduit in left internal thoracic artery-based coronary artery bypass graft surgery: a multi-institutional study

OBJECTIVES: Multiple arterial coronary artery grafting (MABG) improves long-term survival compared with single arterial CABG (SABG), yet the best second arterial conduit to be used with the left internal thoracic artery (LITA) remains undefined. Outcomes in patients grafted with radial artery (RA-MABG) versus right internal thoracic artery (RITA-MABG) as the second arterial graft were compared with SABG. METHODS: Multi-institutional, retrospective analysis of non-emergent isolated LITA to left anterior descending coronary artery CABG patients was performed using institutional Society of Thoracic Surgeon National Adult Cardiac Surgery Databases. 4484 (54.5%) SABG [LITA +/- saphenous vein grafts (SVG)], 3095 (37.6%) RA-MABG (RA +/- SVG) and 641 (7.9%) RITA-MABG (RITA +/- SVG) patients were included. The RITA was used as a free (68%) or in situ (32%) graft. RA grafts were principally anastomosed to the ascending aorta. Longterm survival was ascertained from US Social Security Death Index and institutional follow-up. Triplet propensity matching and covariate-adjusted multivariate logistic regression were used to adjust for baseline differences between study cohorts. RESULTS: Compared with the SABG cohort, the RITA-MABG cohort was younger (58.6 +/- 10.2vs65.9 +/- 10.4, P < 0.001), had a higher prevalence of males (87% vs 65%, P < 0.001) and was generally healthier (MI: 36.7% vs 56.7%, P < 0.001, smoking: 56.8% vs 61.1%, IDDM: 3.0% vs 14.4%, CVA: 2.6% vs 10.0%). The RA-MABG cohort was generally characterized by a risk profile intermediate to that of SABG and RlTA-MABG. Unadjusted 5-, 10- and 15-year survival rates were best in RITA-MABG (95.2%, 89% and 82%), intermediate in RA-MABG (89%, 74%, 57%) and worst in SABG (82%, 61% and 44%) cohorts (all P < 0.001). Propensity matching yielded 551 RA-MABG, RITA-MABG and SABG triplets, which showed similar 30-day mortality. Late survival (16 years) was equivalent in the RA-MABG and RITA-MABG cohorts [68.2% vs 66.7%, P = 0.127, hazard ratio (HR) = 1.28 (0.96-1.71)] and both significantly better than SABG (61.1%). The corresponding SABG versus RITA-MABG and SABG versus RA-MABG HRs (95% confidence interval) were 1.52 (1.18-1.96) and 1.31 (1.01-1.69) with P < 0.002 and P = 0.038, respectively. CONCLUSIONS: RA-MABG or RITA-MABG equally improve long-term survival compared with SABG and thus should be embraced by the Heart Team as the therapy of choice in LITA-based coronary artery bypass surgery.