Is extreme obesity a risk factor for increased in-hospital mortality and postoperative morbidity after cardiac surgery? Results of 2251 obese patients with BMI of 30 to 50

Objective: The number of patients with extreme obesity requiring cardiac surgery is increasing. The aim of the present study was to evaluate the perioperative outcome, complication rate and 30-day mortality of these patients. Methods: Data of 13139 patients (9584 males, 3555 females) undergoing cardiac surgery from 1/94 to 12/04 were analyzed. We compared 2251 obese patients with a BMI of 30 to 50 (mean age 64.3 years; group A) with 10888 non-obese patients (mean age 66.1 years; group B). The incidence of diabetes mellitus was 34.5% in group A, and 24.2% in group B. Results: Isolated CABG was performed in 1771 patients from group A (3.4 grafts/pt.) and in 8066 patients from group B (3.2 grafts/pt.). Concomitant procedures were performed in 460 patients (group A) vs. 2645 (group 13). Frequency of bilateral internal thoracic artery grafting was 49.4% (group A) vs. 44.9% (group B). There were no significant differences between the two groups with regard to the duration of surgery (180 vs. 171 min), the number of reoperations for bleeding (4.7% vs. 5.0%), ventilation times, length of stay in the intensive care unit (2.6 vs. 2.4 days) or 30-day mortality (2.0% vs. 2.8%). The incidence of diabetes and occurrence of sternal dehiscence was higher in group A (1.6% vs. 0.7%; p < 0.01). Sternal complications were strongly associated with diabetes and the combined use of bilateral ITA grafts but not with isolated obesity. The incidence of sternal dehiscence was associated with the male gender (group A 1.9% vs. 0.7%; group B 0.9% vs. 0.3%). Conclusion: Severe obesity does not per se enhance perioperative mortality. A BMI of 30 to 50 combined with diabetes mellitus and bilateral ITA grafting increases the risk for sternal complications.