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Published on: March 27, 2018
Intensity of Glycemic Control Affects Long-Term Survival After Coronary Artery Bypass Graft Surgery
Michael P Robich1, Alexander Iribarne2, Bruce J Leavitt3
1Maine Medical Center, Portland, Maine.
Insights
Higher hemoglobin A1c levels, indicating poorer glycemic control, predict worse long-term survival after coronary artery bypass grafting (CABG), regardless of diabetes status. This highlights the importance of preadmission glycemic control for CABG patient outcomes.
Area of Science:
- Cardiology
- Endocrinology
- Surgical Outcomes
Background:
- Hemoglobin A1c (HbA1c) measures glycemic control and predicts mortality in coronary artery bypass grafting (CABG) patients.
- Previous studies indicate HbA1c is an independent predictor of short-term death post-CABG.
- This study investigates the association between preoperative HbA1c levels and both short-term and long-term survival after CABG.
Purpose of the Study:
- To assess the relationship between preoperative hemoglobin A1c (HbA1c) levels and survival outcomes in patients undergoing coronary artery bypass grafting (CABG).
- To determine if elevated HbA1c, irrespective of diabetes diagnosis, impacts in-hospital and long-term survival post-CABG.
Main Methods:
- A cohort of 6,415 patients undergoing on-pump isolated CABG between 2008-2015 with documented preoperative HbA1c levels were analyzed.
- Patients were categorized into four HbA1c groups: <5.7%, 5.7%-6.4% (prediabetes), 6.5%-8.0%, and >8.0%.
- In-hospital outcomes and long-term survival were assessed using multivariable logistic regression and Cox models, adjusting for risk factors.
Main Results:
- Higher preoperative HbA1c levels were associated with younger age, female sex, higher BMI, more comorbidities, and greater coronary disease severity.
- No significant association was found between higher HbA1c values and increased in-hospital death or morbidity after risk adjustment.
- Long-term survival significantly worsened with increasing HbA1c levels, with a 13% increased risk of death per unit increase in HbA1c (aHR=1.13).
Conclusions:
- Preadmission glycemic control, indicated by HbA1c levels, is a significant predictor of long-term survival following CABG.
- Elevated HbA1c levels are associated with a poorer long-term prognosis in CABG patients, independent of diabetes status.
- Further research is needed to determine if postoperative glycemic control can modify this increased long-term mortality risk.
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.
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