OBJECTIVE: We aimed to examine the long-term clinical outcomes, graft patency, and remodeling capacities of onlay anastomoses using 4 different grafts. METHODS: The cross-sectional areas of onlay anastomoses were measured using coronary angiography or computed tomography and compared with the estimated standard areas of normal arteries to assess changes in the onlay anastomosis area over time. RESULTS: One hundred eight patients underwent onlay grafting (with coronary endarterectomy: 43 arteries
without: 84). The operative mortality rate was 1.85%, and the average follow-up period was 102.8 ± 52.4 months (range, 6-217 months). The reintervention-free rate was 99.2%, and late death occurred in 30 patients, including 6 cardiac deaths. The estimated survival rates were 93.6%, 79.0%, 71.3%, 56.1%, and 48.1% at 1, 5, 10, 14, and 18 years, respectively. Early angiography in 93 patients resulted in a 98.1% patency rate. Follow-up angiography on 78 patients showed a distant patency rate of 96.6% at an average of 52.7 ± 42.5 months (range, 6-180 months). Early enlargement of the onlay anastomosis reduced its size to match the native standard lumen long-term, regardless of the graft material used. CONCLUSIONS: Onlay grafting, with or without endarterectomy, maintained anastomotic patency with major branch preservation and favorable long-term remodeling of the anastomoses, leading to luminal equalization and smoothing.