Short-Term Risk of Bilateral Internal Mammary Artery Grafting in Diabetic Patients

This study compares the morbidity and mortality at 30 days following the use of bilateral internal mammary arteries (BIMA) vs a single internal mammary artery (SIMA) at the time of coronary artery bypass grafting (CABG) in patients with a preoperative HbA1c. Patients undergoing CABG from January 2008 to December 2016 reported to the Society of Thoracic Surgeons database were retrospectively reviewed. The patients were divided into 2 groups: use of BIMA or use of SIMA and propensity matched. To assess the effect of preoperative HbA1c, both groups were further divided into 5 subgroups: patients without diabetes mellitus (DM), or patients with DM and a preoperative HbA1c level in one of four groups (< 7%, 7-9%, 9-11%, or >11%). The postoperative outcomes in both the BIMA and SIMA groups were compared. There were 700,504 and 28,115 patients with measured preoperative HbA1c levels in the SIMA and BIMA groups, respectively. Propensity score matching identified 23,635 comparable patients in each group for analysis. There was no difference in postoperative mortality between the BIMA and SIMA groups (1.3% vs 1.2%). The incidences of sternal wound infection (SWI) in patients undergoing placement of BIMA vs SIMA were: 0.8% vs 0.4% with no DM (P < 0.0001), 1.9% vs 1.0% with HbA1c < 7% (P < 0.001), 2.4% vs 1.2% with HbA1c 7-9% (P < 0.001), 2.8% vs 1.4% with HbA1c 9-11% (P = 0.02), 4.1% vs 1.5% with HbA1c > 11% (P = 0.01). Based on the incidence of SWI, BIMA is a reasonable approach with an HbA1c<7%.