307: Bilateral internal mammary artery bypass grafting: long-term clinical benefits of a consecutive series of 1000 patients

Abstract

Bilateral internal mammary arteries (BIMA) remain still widely underutilized in coronary artery bypass grafting (CABG). This historical cohort study evaluated the early and long term outcomes of BIMA grafts in isolated CABG in a single institution. Between 1996 and 2008, we performed elective, isolated, primary, multiple CABG using bilateral internal mammary artery (IMA) grafts and supplemental venous grafts for multivessel coronary disease in 1000 consecutive patients. The mean age of the overall population was 64±15 years. 20% of patients were diabetics with a left ventricular ejection fraction (LVEF) ≤45% in 28% of patients. Comorbidities were represented by chronic renal failure, chronic obstructive pulmonary disease and peripheral artery disease in 11%, 11,5% and 26,9% of cases respectively. Acute coronary syndrome represented the initial clinical presentation in 41% of cases. The 30-day mortality rate was 2.8%. Early postoperative morbidity included myocardial infarction (2,2%), stroke (0,9%), mesenteric ischemia (0,7%), sternitis requiring reintervention (6,7%) and supraventricular arrhythmia (23,1%). The follow-up (between 3 and 14,8 years; mean follow up: 6,4±5 years) revealed 103 deaths. Kaplan-Meier 8-year survival rates for patients <65 and 65 to 74 years of age were 88% and 66% respectively (p<0,01). Multiple regression analysis showed that age ≥ 65 years at baseline (odds ratio (OR): 2,3; 95% confidence interval (CI): 1,3 to 4, p<0,001), acute coronary syndrome (OR: 1,9; 95% CI: 1,1 to 3,4, p=0,02), chronic renal failure (OR: 2,7; 95% CI, 1,4 to 5,2, p<0,001), peripheral artery disease (OR: 3,1; 95% CI, 1,8 to 5,5, p<0,001) and LVEF ≤45% (OR: 2,6; 95% CI, 1,4 to 4,5, p<0,001) were independent predictors of long term cardiovascular mortality. Our longitudinal analysis demonstrates that bilateral IMA grafting has a low operative risk and provides excellent long-term survival.