Intensity of Glycemic Control Affects Long-Term Survival After Coronary Artery Bypass Graft Surgery

Ann Thorac Surg. 2019 Feb;107(2):477-484. doi: 10.1016/j.athoracsur.2018.07.078. Epub 2018 Sep 28.


Background: A patient's hemoglobin (Hb) A1c level, regardless of diabetic status, is a measure of glycemic control. Studies have found it is an independent predictor of short-term death in patients undergoing coronary artery bypass grafting (CABG). In this study, we used preoperative HbA1c to assess whether levels are associated with short-term and long-term survival after CABG.

Methods: From a regional registry of consecutive cases, we identified 6,415 patients undergoing on-pump isolated CABG from 2008 to 2015 with documented preoperative HbA1c level. We defined four HbA1c groups: less than 5.7% (n = 1,713), 5.7% to 6.4% (n = 2,505), 6.5% to 8.0% (n = 1,377), and more than 8% (n = 820). Relationship to in-hospital outcomes and long-term survival was assessed. Outcome rates and hazard ratios were adjusted for patient and disease risk factors using multivariable logistic regression and Cox models.

Results: The study included 3,740 patients (58%) not diagnosed as having diabetes and 2,674 with diabetes. Prediabetes (HbA1c 5.7% to 6.4%) was documented in 52% (n = 1,933) of nondiabetic patients. Higher HbA1c values were associated with younger age, female sex, greater body mass index, more comorbid diseases, lower ejection fraction, more 3-vessel coronary disease, and recent myocardial infarction (p < 0.05 trend for all). After adjustment for patient risk, greater HbA1c values were not associated with higher rates of in-hospital death or morbidity. Long-term survival was significantly worse as HbA1c increased. Risk of death increased by 13% for every unit increase in HbA1c (adjusted hazard ratio, 1.13; 95% confidence interval, 1.07 to 1.19; p < 0.001).

Conclusions: Preadmission glycemic control, as assessed by HbA1c, is predictive of long-term survival, with higher levels associated with poorer prognosis. Whether this risk can be modified by better glycemic control postoperatively remains to be determined.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Blood Glucose / metabolism*
  • Coronary Artery Bypass*
  • Coronary Artery Disease / blood
  • Coronary Artery Disease / surgery*
  • Diabetes Mellitus / blood
  • Diabetes Mellitus / mortality*
  • Female
  • Follow-Up Studies
  • Glycated Hemoglobin A / metabolism*
  • Humans
  • Male
  • Middle Aged
  • Postoperative Period
  • Registries*
  • Risk Factors
  • Survival Rate / trends
  • Time Factors
  • United States / epidemiology


  • Blood Glucose
  • Glycated Hemoglobin A