Hyperglycemia predicts mortality after CABG: postoperative hyperglycemia predicts dramatic increases in mortality after coronary artery bypass graft surgery

Abstract

Objective Risk of morbidity and mortality after coronary artery bypass graft surgery (CABG) is higher in patients with clinical diabetes mellitus (DM). We evaluated whether outcomes are affected by postoperative hyperglycemia in CABG patients independent of preoperative DM diagnosis. Research Design and Methods A total of 2297 consecutive CABG patients were studied. The first glucose value after surgery completion (mean 15 min) was tested as a predictor of outcome. Primary outcome variables were prolonged ventilation (>24 h), deep sternal wound infection, renal failure, permanent stroke, any reoperation, length of stay (>14 days) and mortality. All outcomes except for prolonged ventilation and length of stay were tracked out to 30 days postoperatively. Patients were stratified by glycemic control: Low (glucose <80), normal (referent, glucose 80–110), high (glucose 111–200) and very high (glucose >200 mg/dl). Multivariable logistic regression was used to determine the independent predictive value of glycemic groups, adjusted for outcome specific risk scores from the Society of Thoracic Surgeons model. Results Patient distribution among groups low through very high were 44 (1.9%), 476 (20.7%), 1425 (62.0%) and 352 (15.3%). Greater complication rates were noted in the very high group when compared with the referent group: prolonged ventilation (adjusted odds ratio (OR)=2.66, P<.001), length of stay >14 days (adjusted OR=2.06, P=.004) and mortality (adjusted OR=7.71, P<.001). Conclusion Patients with blood glucose values >200 mg/dl immediately after CABG had an increased risk of complications, including mortality, independent of a clinical diagnosis of DM. This study documents the high risk associated with early postoperative hyperglycemia in this group, suggesting the need for prospective trials of glycemic control.