The impact of diabetic status on coronary artery bypass graft patency - Insights from the radial artery patency study

Background-Despite worse outcomes in diabetics after coronary artery bypass grafting surgery, studies have not examined graft patency in this high-risk group. This study examined the impact of diabetes on graft patency, 1-year postcoronary artery bypass grafting, using data from a multicenter randomized trial. Methods and Results-The Radial Artery Patency Study enrolled 561 patients undergoing coronary artery bypass grafting, comparing graft patency of the saphenous vein (SV) versus radial artery 1-year postcoronary artery bypass grafting. Angiographic follow-up was acquired for 440 patients (115 diabetics, 325 nondiabetics), each with a study radial artery and a control SV graft. Preoperative characteristics were similar. The proportion of small-sized target vessels was greater in diabetics (P = 0.04). At 1 year, 33 of 230 study grafts (14.4%) were occluded in the diabetics versus 63 of 650 (9.7%) in the nondiabetics (P = 0.052). Multivariable regression found diabetes to be a significant independent predictor of 1-year graft occlusion (relative risk, 1.45; 95% CI, 1.03 to 2.05; P = 0.03) along with female gender, SV conduit, and small target-vessel size. A significantly higher proportion of SV grafts were occluded in the diabetics (19% versus 12%, P = 0.04). Radial artery grafting was protective in the diabetic cohort (radial artery: 11 of 115 occluded [9.5%] versus SV: 22 of 115 occluded [19.1%], McNemar corrected P = 0.05; relative risk, 0.42; 95% CI, 0.16 to 1.01) and nondiabetics (radial artery: 25 of 325 occluded [7.7%] versus SV: 38 of 325 occluded [11.7%], McNemar corrected P = 0.11; relative risk, 0.63; 95% CI, 0.35 to 1.10). Conclusions-Coronary artery bypass grafting occlusions were more common among diabetics versus nondiabetics at 1-year angiography, mainly because of more frequent SV graft failure in diabetics. Radial artery, compared with SV grafting, is protective in both diabetic and nondiabetic patients.