Abstract 2882: The Impact of Diabetic Status on Coronary Bypass Graft Patency: Insights from the Radial Artery Patency Trial
BACKGROUND: Despite worse outcomes in diabetics after coronary artery bypass grafting (CABG) surgery, clinical trials have not examined graft patency in this high risk group. This study aimed to determine the impact of diabetes on graft patency at 1-year after CABG, using data from a multicentre randomized clinical trial.
METHODS: The Radial Artery Patency Trial enrolled 561 patients undergoing CABG, comparing graft patency of the saphenous vein (SV) versus radial artery (RA) at 1-year post-CABG. Randomization was within patients. Multivariable models accounted for within patient clustering, demographics, operative factors and post-discharge medication.
RESULTS: Angiographic follow-up was acquired for 440 patients at 1-year, each with a study RA and a control SV graft: 325 non-diabetic patients and 115 diabetics (93 oral therapy, 22 insulin). There were more females in the diabetic cohort (19% vs 11%, p=0.02); other pre-operative characteristics were similar. The number of distal anastomoses was similar. The proportion of small sized target vessels was greater in diabetic patients (p=0.04). At 1-year, 33/230 study grafts (14.4%) were occluded in the diabetic group versus 63/650 (9.7%) in the non-diabetic group (p=0.052). Multivariable regression found diabetes to be a significant independent predictor of 1-year graft occlusion (RR 1.45, 95% CI 1.03–2.05, 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 diabetic group (19% vs 12%, p=0.04). Radial artery grafting was protective in the diabetic cohort (RA: 11/115 occluded [9.5%] vs SV: 22/115 occluded [19.1%], McNemar’s corrected p=0.05, RR 0.42, 95% CI 0.16–1.01) and non-diabetics (RA: 25/325 occluded [7.7%] vs SV: 38/325 occluded [11.7%], McNemar’s corrected p=0.11, RR 0.63, 95% CI: 0.35–1.10). Clinical outcomes were no different between diabetics and non-diabetics by 1-year.
CONCLUSIONS: Coronary bypass graft occlusions were more common among diabetics versus non-diabetics at 1-year follow-up angiography, mainly because of more frequent SV graft failure in diabetics. RA, compared to SV grafting, is protective in both diabetic and non-diabetic patients.