Propensity-matched analysis of bilateral internal mammary artery vs single internal mammary artery in 7702 cases of isolated coronary artery bypass grafting

OBJECTIVES: To evaluate early outcomes of bilateral internal mammary artery (BIMA) compared with single IMA (SIMA) in patients who underwent isolated coronary artery bypass grafting (CABG). METHODS: Patients who received isolated CABG with SIMA or BIMA were retrospectively reviewed using the Japan Adult Cardiovascular Surgery Database from 210 institutions for 2008 and 2009. We performed a one-to-one matched analysis on the basis of estimated propensity scores for patients receiving either SIMA or BIMA and obtained two cohorts with 3851 patients in each group balanced for baseline characteristics out of 8136 SIMA and 4093 BIMA patients. We compared procedures actually performed, early outcomes including 30-day operative mortality and details of postoperative complications between the groups using Pearson's chisquare test, with P < 0.05 being statistically significant. RESULTS: Preoperative profiles in both groups included 20% females and 50% diabetes mellitus patients with a mean age of 67 years. Off-pump CABG was similar in both groups, being performed 75% of the time, with the mean number of anastomosis being 3.1 and 3.4 in the SIMA and BIMA groups, respectively (P < 0.0001). Thirty-day operative mortality was 1.2% in both groups, and the overall incidence of postoperative complications also was similar, although deep sternal infection was more frequent with BIMA (1.3 of SIMA and 2.3% of BIMA patients; P = 0.0001), while prolonged ventilation and renal failure were more frequent with SIMA (P < 0.05). CONCLUSIONS: The use of BIMA did not affect either short-term survival as postoperative mortality was low in both groups, or overall morbidity despite higher incidence of deep sternal infection.