Influence of preoperative hemoglobin A1c on early outcomes in patients with diabetes mellitus undergoing off-pump coronary artery bypass surgery

Objective: There seem to be modifiable components of diabetes in terms of glycemic control to improve surgical outcome. The aim of the study was to evaluate impact of preoperative glycated hemoglobin (HbA1c) level in patients with diabetes mellitus undergoing off-pump coronary bypass (OPCAB) on perioperative glycemic variability and short-term outcome.

Methods: Medical records of 703 patients with diabetes mellitus who underwent OPCAB from 2005 to 2017 were reviewed. The perioperative goal of glycemic control was <180 mg/dL. Patients were divided into 2 groups according to HbA1c level (<7.0% or ≥7.0%). Glycemic variability during surgery and up to 24 hours after surgery was assessed by coefficient of variation (CV). Primary outcome was defined as composite of postoperative permanent stroke, prolonged ventilation, deep sternal wound infection, renal failure, reoperation, and 30-day mortality.

Results: Incidence of composite of postoperative morbidity and mortality endpoints was greater in patients with HbA1c ≥7.0% (21% vs 15%, P = .041). Perioperative time-weighted average glucose concentration was also greater in patients with HbA1c ≥7.0%, whereas the CV did not show any difference. Multivariable logistic regression analysis revealed that congestive heart failure, chronic kidney disease, moderate mitral regurgitation or greater, preoperative hemoglobin level, and preoperative HbA1c ≥7.0% were independently associated with composite of postoperative morbidity and mortality, but perioperative CV and time-weighted average glucose ≥200 mg/dL were not.

Conclusions: Increased preoperative HbA1c (≥7.0%) level reflecting long-term glycemic control seems to exert an adverse influence on outcome, whereas the influence of perioperative glycemic variables appear to be abrogated using a target glucose level of <180 mg/dL in patients with diabetes mellitus undergoing OPCAB.