Methods: Between August 2007 and March 2011, a total of 1,673 consecutive patients (1,209 males, 464 females; mean age 58.6±9.9 years; range 21 to 87 years) who underwent isolated CABG at Shariati Hospital, Tehran, Iran were retrospectively analyzed. The patients were classified into four groups based on the BMI values: underweight (BMI ≤19 kg/m², n=55), normal/overweight (BMI 20-29 kg/m², n=523), obese (BMI 30-39 kg/m², n=739) and morbidly obese (BMI ≥40 kg/m², n=356). Preoperative characteristics were compared among the four groups. Effects of BMI on postoperative mortality and morbidity were evaluated using the stepwise multivariate logistic regression analysis.

Results: There was no significant difference in the mortality rate among the groups. Intra-aortic balloon pump (IABP) was the only independent predictor of postoperative mortality in the multivariate logistic regression analysis (OR=20.5, 95% CI=8.6-50.5; p<0.001). Body mass index was independently associated with postoperative pulmonary complications (OR=1.6, 95% CI=1.2-2.1; p=0.001).

Conclusion: Our study results suggest that BMI is an independent predictor of post-CABG pulmonary complications, but not of post-CABG mortality.