Off-Pump Coronary Artery Bypass Grafting Using Bilateral Internal Mammary Artery: Clinical Follow-up and 20-Year Postoperative Survival

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Abstract

Background: Off-pump coronary artery bypass (OPCAB) surgery using bilateral internal mammary arteries (BIMA) has demonstrated improved mid-term survival and reduced perioperative risk. However, evidence regarding its long-term effectiveness and safety remains limited, particularly in Latin American populations.

Objectives: To describe long-term survival (20 years) in a consecutive cohort of patients undergoing exclusively OPCAB surgery with BIMA and to assess the impact of age, ventricular function, diabetic status, and body mass index (BMI) on survival.

Methods: This retrospective open cohort study included patients who underwent exclusively OPCAB surgery with BIMA between January 2003 and December 2023. Emergency surgeries, combined procedures, and patients with prior heart surgery were excluded. Follow-up ranged from a minimum of 1 year to 20 years after surgery. Demographic characteristics were obtained from medical records, and survival status was assessed by telephone follow-up. For the primary endpoint, survival was estimated using tables and Kaplan-Meier curves. Cox proportional hazards regression models were used to evaluate associations between time to death and age, ventricular function, type of angina, diabetic status, and BMI. Unadjusted and adjusted hazard ratios (HR) with 95% confidence intervals (CI) were reported.

Results: During the study period, 4495 patients were included, with a median follow-up of 6.13 years (interquartile range, IQR, 2.62-10.36). The mean age was 64.1 ± 9.27 years, and 8.34% (n = 375) were women. A total of 28.2% (n = 1269) had diabetes. The median BMI was 28 (IQR 25.8–30.5). Overall survival was 70% (95% CI 68-72%) at 10 years and 31% (95% CI 28-34%) at 20 years. In patients aged ≤65 years, survival was 87.8% (95% CI 85.8-89.6) at 10 years and 60.8% (95% CI 55.6-65.7) at 20 years. Age >65 years (adjusted HR 4.99; 95% CI 4.33-5.75; p <0.001) and severe ventricular dysfunction (adjusted HR 2.20; 95% CI 1.73-2.80; p <0.001) were independently associated with higher postoperative mortality. Diabetes was an independent predictor of mortality both without obesity (adjusted HR 1.30; 95% CI 1.13-1.50; p <0.001) and with obesity (adjusted HR 1.28; 95% CI 1.05-1.56; p = 0.015), whereas obesity without diabetes was not (adjusted HR 1.05; 95% CI 0.88-1.24; p = 0.603). Conclusion: In this 20-year retrospective cohort, off-pump CABG with BITA demonstrated high long-term survival in younger patients. Severe ventricular dysfunction and diabetes, with or without obesity, were independently associated with increased mortality, whereas obesity and was not independent an independent predictor of mortality.