**8. RIMA versus radial artery as a second choice arterial conduit**

With favorable clinical results for both RIMA and radial artery use, it is then necessary to decide which is the better choice as a second arterial conduit when attempting to achieve multiple arterial revascularization.

Ruttman *et al.* studied 1,001 patients undergoing CABG procedures either receiving RIMA grafts or radial artery grafts as second conduits after LIMA grafts with or without concomitant saphenous vein grafts added when necessary. Propensity-score matched analysis was performed on the two patient groups to examine the short and long-term outcomes of BIMA grafting versus LIMA plus radial artery grafting. Overall, the evidence provides strong support for the use of the RIMA over the radial artery as a second choice arterial conduit. Radial artery graft occlusion and disease rates were significantly higher than both IMA and saphenous vein anastomoses, with occlusion/disease rates of 37.9%, 10.2%, and 20.9%, respectively. Survival rates for BIMA grafting were 98.9% at 1, 3, and 5 years post-operatively, compared with rates for the radial artery group of 96.8%, 96.3%, and 93.0% at the same postoperative years. The BIMA group also had significantly higher rates of major cardiac and cerebrovascular events-free survival than the radial artery group at the same yearly intervals post-operatively [32].

In a 10-year prospective, randomized trial, Hayward *et al.* examined angiographic out‐ comes of patients receiving either a radial artery, RIMA, or saphenous vein graft to the second largest coronary target after the LAD, which was grafted with the LIMA. Patients were randomized to two groups: those less than 70 years of age received either a radial artery or RIMA as the second arterial conduit, and those greater than 70 years of age re‐ ceived either a radial artery or saphenous vein. At a mean follow up of 5.5 years, a total of 350 patients between the two groups had angiography performed. In the first group, Kaplan-Meier estimates of graft patency were 89.8% for the radial artery and 83.2% for the RIMA (p = 0.06). In the second group, patency estimates were 90.0% for the radial ar‐ tery and 87.0% for the saphenous vein (p = 0.29). With no significant difference in the pa‐ tency rates between the conduits in each of the two groups, the results show that the choice of conduit for the second largest coronary target does not significantly affect pa‐ tency, giving surgeons flexibility in their revascularization plans [33].
