612 Is Preoperative HbA1c a Predictive Biomarker of Postoperative Mortality and Morbidity in Patients Following Coronary Artery Bypass Graft Surgery

Haemoglobin A1c (HbA1c) is a blood-based biomarker that represents impaired glucose tolerance. Patients undergoing coronary artery bypass grafting (CABG) commonly have an elevated HbA1c, regardless of a prior diagnosis of diabetes mellitus. However, few studies have investigated HbA1c as a predictor of postoperative outcomes in a cohort of both diabetic and non-diabetic patients. This study sought to investigate the utility of preoperative HbA1c as a predictive biomarker of 30-day mortality and other major complications in all patients undergoing elective CABG. All patients identified from the ANZSCTS database (2010-2019) undergoing elective on-pump CABG at St Vincent’s Hospital, Melbourne with documented HbA1c levels were included (n=1,990). Patients were stratified into two groups by HbA1c levels (<6.5 or >=6.5) and chi-squared test used to compare incidence of postoperative outcomes in our primary analysis. Secondary analysis was performed using HbA1c as a continuous linear predictor, and correlation with outcomes assessed through multivariable logistic regression analysis. Increasing HbA1c level was independently associated with increased ICU readmission (OR 1.21 per one-unit increase, p<0.01) and sternal wound infection (OR 1.36, p=0.05). Furthermore, elevations in HbA1c level were negatively correlated with incidence of atrial fibrillation (OR 0.87, p<0.01). There was no statistically significant association between an elevated HbA1c and 30-day mortality (p=0.54). HbA1c may be a quick, inexpensive biomarker to predict those patients at increased risk of ICU readmission, sternal wound infection and atrial fibrillation following elective CABG, independent of their diabetic status.