Association between HbA1c levels and clinical outcomes in patients undergoing ısolated coronary artery bypass grafting

Purpose: Several studies have indicated that elevated HbA1c levels may increase adverse postoperative outcomes in cardiac surgery. However, the consistency of this relationship remains unclear. This study aimed to evaluate the impact of preoperative HbA1c levels on postoperative clinical outcomes in patients undergoing isolated coronary artery bypass grafting (CABG). Materials and methods: A total of 169 patients who underwent elective, primary, isolated CABG under cardiopulmonary bypass (CPB) between January 2022 and January 2024 were retrospectively analyzed. Patients were divided into three groups based on their preoperative HbA1c levels: Group I (<5%), Group II (5-6.5%), and Group III (>6.5%). Demographic characteristics, preoperative risk factors, operative details, and postoperative complications were recorded. Logistic regression analysis was used to assess the relationship between HbA1c levels and postoperative outcomes such as atrial fibrillation, sternal wound infection, and chest tube drainage. Results: The prevalence of diabetes mellitus (82.1%) and peripheral arterial disease (32.8%) was significantly higher in Group III (p<0.05). Postoperative complications, including sternal wound infection (p=0.036), atrial fibrillation (p=0.006), and higher 24-hour drainage volume (p=0.01), were more frequent in this group. HbA1c >6.5% was an independent predictor of sternal wound infection (OR:3.81; 95% CI:1.25-11.5) and atrial fibrillation (OR:2.25; 95% CI:1.17-4.32). Additionally, HbA1c positively correlated with drainage volume (r=0.172, p=0.026) and erythrocyte suspension usage (r=0.201, p=0.01). Conclusion: High preoperative HbA1c levels are associated with increased risk of postoperative complications. HbA1c may serve as a valuable predictor of adverse outcomes, and optimizing glycemic control before surgery could improve prognosis.