Prevalence and clinical significance of elevated preoperative glycosylated hemoglobin in diabetic patients scheduled for coronary artery surgery.

OBJECTIVE

To establish what is the prevalence of elevated HbA1c among diabetic patients scheduled for coronary surgery and whether this may influence their postoperative outcome.

METHODS

We performed a retrospective review of our departmental cardiac surgical database over a 3-year period (2006-2008). Among the 2665 patients, who underwent coronary revascularization, 782 (29.3%) patients had diabetes mellitus, with 735 (94.0%) patients having their HbA1c assessed preoperatively up to 3 days before the start of the procedure. Patients with preoperative normal or elevated HbA1c (>7%) were compared regarding their hospital mortality, morbidity (defined as any postoperative complication such as stroke, renal failure, wound infection, perioperative myocardial infarction (MI), and others) as well as mean intensive care unit (ICU) and hospital stay. Patients for comparisons were matched to achieve similar preoperative status with a use of a Greedy matching procedure. Chi-square test was performed to compare variables of interest; p<0.05 was considered significant.

RESULTS

Elevated HbA1c levels were present in 38.4% of diabetic patients - 57.1% of patients among insulin-dependent diabetics, 27.3% of patients on oral medication, and in 7.7% of patients whose diabetes was treated with diet only. In a direct comparison and after matching for preoperative variables, elevated HbA1c levels increased only the frequency of perioperative MI (p=0.01). Other complications, length of ICU and hospital stay as well as early mortality were similar in both the groups.

CONCLUSIONS

Elevated HbA1c levels are common among diabetic patients scheduled for coronary surgery, particularly in patients receiving insulin, and are associated with more frequent occurrence of perioperative MI.