Study of association of preoperative glycosylated haemoglobin level and outcome after cardiac surgery

Background:  Diabetes mellitus involves 8.7% of the adult community in India, and its preponderance is rising.  Diabetes is an independent risk factor for complications after open cardiac surgery. Poor glycaemic control, measured by glycosylated haemoglobin A_1C (HbA_1c), is associated with high incidence of micro and macroangiopathy. HbA1c reflects the patient's prevailing sugar control over the previous 120-150 days.  Perioperative cardiac surgical risk scoring systems like Euro Score and STS scoring systems do not include HbA1c level as risk factor. We intended to study the correlation of preoperative HbA1c level and outcome after cardiac surgery.

Methodology:  A total of 350 patients who had undergone elective cardiac surgery were included. All patients were stratified into two groups, Group 1 with HbA_1c level < 7%, Group 2 >7%. Intraoperative and postoperative adverse events were documented retrospectively. The two groups of patients were compared with regard to their demographic data, operation risk, mortality and morbidity.

Results: Overall incidence of major adverse events (7.7%) and mortality (4.8%) were very low.  Incidence of sternal wound infection and prolonged ventilator support (> 24 hrs) were significant in group 2 compared to group 1 (p values were 0.03 and 0.01 respectively).

Conclusion: Preoperative HbA1c level may provide more accurate prognostic information about outcomes after all major open cardiac surgeries compared with a diabetes status alone.