BACKGROUND: The aim of this retrospective study was to evaluate whether the level of preoperative glycosylated hemoglobin (HbA1c) is associated with incidence of major adverse events in patients undergoing elective coronary bypass surgery.
METHODS: This was a retrospective observational study of 1,116 patients undergoing elective, isolated aortocoronary bypass surgery over a period of 5 years. Two groups were investigated, one with a preoperative HbA1c level ≤6.5% and the other with HbA1c superior to 6.5%. We used propensity modelling to calculate inverse probability of treatment weights (IPTW) for quantifying the association of increased HbA1c on outcome.
RESULTS: According to inclusion criteria, 589 patients (mean age, 68.1 years; female:14%) were included in the analysis. HbA1c was ≤ 6.5% in 410 patients (69.6%) and was higher than 6.5% in 179 patients (30.4%). The in-hospital mortality rate before and after IPTW was not significantly higher in HbA1c>6.5% groups (1.0% vs. 3.4% p=0.054 and 1.1% vs. 3.5% p=0.076). After IPTW, the risk for major cardiovascular events was higher in patients with HbA1c>6.5%, odds ratio [OR] 3.19, confidence interval [CI] 1.48 to 6.87, p=0.003, and the risk for sternal infection OR 8.07 (CI 2.79-23.39, p<0.001), for sepsis OR 5.36 (CI 1.56 -18.46, p=0.008), and renal failure OR 3.16 (CI 1.12-8.88, p=0.03).
CONCLUSION: Preoperatively, inadequately-treated diabetes mellitus that may be expressed as elevated HbA1c, which is directly associated with an elevated incidence of adverse events following elective coronary revascularization surgery.
