Early and long-term outcomes of bilateral internal mammary artery versus radial artery grafting: A national cohort study.

OBJECTIVE: To compare early and long-term outcomes of bilateral internal mammary artery (BIMA) grafting versus left internal mammary artery (LIMA) plus radial artery (RA) grafting in patients undergoing isolated coronary artery bypass grafting (CABG). METHODS: This retrospective national cohort study included patients undergoing isolated CABG with multiarterial grafting in Uruguay between 2002 and 2022. Patients undergoing BIMA grafting or LIMA+RA grafting were identified from a mandatory national cardiac surgery database. Propensity score matching with multiple imputation was used to balance baseline characteristics between the 2 groups. Long-term survival was assessed using Kaplan-Meier analysis, Cox proportional hazards models, and restricted mean survival time (RMST). Competing-risk regression (Fine-Gray) was used to evaluate repeat percutaneous coronary intervention. Effect modification by sex and diabetes was explored. RESULTS: Among 2882 patients (2132 BIMA and 750 LIMA+RA), 4203 matched (with replacement) patients were analyzed. At 10 years, RMST did not differ between groups (9.06 years for BIMA vs 8.98 years for LIMA+RA; P = .36), and BIMA grafting was associated with improved long-term survival (hazard ratio, 0.73; 95% confidence interval, 0.55-0.93; P = .03) which was not supported by sensitivity analyses. There was no interaction with sex or with diabetes. BIMA grafting was associated with lower operative mortality but with a higher rate of mechanical ventilation and longer duration of inotrope use. No between-group differences were observed in major ischemic events, deep sternal wound infection, or repeat revascularization. CONCLUSIONS: In this national cohort, BIMA grafting improved early outcomes but did not confer a consistent overall long-term survival advantage compared with LIMA+RA grafting. A lack of support from sensitivity analyses implies the need for an individualized approach.