Elevated glycosylated haemoglobin (HbA1c) is a risk marker in coronary artery bypass surgery

Abstract

Objective: To evaluate if glycosylated haemoglobin 1 (HbA1c) was associated with increased risk of infection and mortality after coronary artery bypass grafting (CABG).

Design: Prospective observational study. Preoperative HbA1c concentrations were correlated to outcome in patients followed for an average of 3.5 years after CABG.

Results: HbA1c was > or =6% in 68% of 161 patients with diabetes mellitus (DM) and in 3% of 444 patients without DM. Superficial sternal wound infection was observed in 13.9% if HbA1c > or =6% versus in 5.5% if <6% (p=0.007). Mediastinitis occurred in 4.9% if HbA1c > or =6% and in 2.1% if HbA1c <6% (p=0.20) (Hazard ratio (HR) 1.9, 95% CI 0.6-5.9). Follow-up mortality was 18.9% in patients with HbA1c > or =6% compared to 4.1% if HbA1c <6% (p<0.001) with HR 5.4, (95% CI 3.0-10.0) after multivariable adjustment. The risk of death was similar regardless of DM diagnosis.

Conclusions: HbA1c > or =6% was associated with an increased risk of postoperative superficial sternal wound infections and a trend for higher mediastinitis rate and significantly higher mortality three years after CABG.