Coronary surgery in patients with diabetes mellitus: a risk-adjusted study on early outcome

We aimed at determining the effect of diabetes mellitus (diabetes) on short-term mortality and morbidity in a cohort of patients with ischemic disease undergoing coronary artery bypass surgery (CABG) at our institution.

A total of 4567 patients undergoing isolated CABG in a 10-year period were studied. Diabetes mellitus was present in 22.6% of the cases but the percentage increased from 19.1% in the beginning to 27% in the end of the study period (p<0.0001 for the decade time-trend). Compared with non-diabetic patients, the group with diabetes was older (61.5+/-8.4 years vs 60.4+/-9.5 years), had a higher body mass index (26.4+/-2.2 vs 26.0+/-2.2), comprised more women (17.5% vs 10.1%), and had a greater incidence of peripheral vascular disease (13.3% vs 8.8%), cerebrovascular disease (8.3% vs 4.3%), renal failure (2.7% vs 1.1%), cardiomegaly (14.0% vs 10.9%), class III-IV angina (43.4% vs 39.0%), triple-vessel disease (80.9% vs 73.7%) and patients with left ventricular dysfunction (all p<0.05). Demographic and peri-procedural data were registered prospectively in a computerized institutional database. Multivariate logistic regression was performed to assess the influence of diabetes as an independent risk factor for in-hospital mortality and morbidity.

The overall in-hospital mortality was 0.96% [n=44; diabetics: 1.0%, non-diabetics: 0.9% (p=0.74)]. The mortality of patients with diabetes decreased from 2.7% in the early period to 0.7% in the late period (p=0.03 for the time-trend). Postoperative in-hospital complications were comparable in the two groups in univariate analysis, with only cerebrovascular accident and prolonged length of stay being significantly higher in the diabetic patients (all p<0.05). In multivariate analysis, diabetes was not found to be an independent risk factor for in-hospital mortality (OR=0.61; 95% CI=0.28-1.30; p=0.19), but predicted the occurrence of mediastinitis (OR=1.80; 95% CI=1.01-3.22; p=0.049).

Despite worse demographic and clinical characteristics, diabetic patients could be surgically revascularized with low mortality and morbidity, comparable with control patients. Hence, our data do not support diabetes as a risk factor for significantly adverse early outcome following CABG.