Body mass index and outcome after coronary artery bypass surgery

Morbidity and mortality after surgical interventions are influenced by different preoperative factors. We investigated the impact of body mass index (BMI) on outcome after coronary artery bypass grafting (CABG).

A total of 4 749 CABG patients were divided into 4 groups: low BMI (or=35 kg/m(2), n=146). The incidence of severe perioperative complications (heart failure, renal failure or perioperative stroke), 30-day mortality, length of stay (LOS) and long-term survival were compared. A multivariate analysis with BMI, age, gender and Cleveland Clinic risk score as independent variables and 30-day mortality as dependent variable was performed.

Compared to patients with normal BMI, low BMI patients had higher incidence of severe complications (12.5 vs 7.0%, P=0.039), higher 30-day mortality (6.2 vs 1.7 %, P=0.001) and inferior cumulative long-term survival (P=0.04). Patients with moderately increased BMI had longer LOS (10.8 vs 9.0 days, P=0.003) but no difference in incidence of severe complications or mortality. Patients with severely increased BMI had a higher incidence of severe complications (12.3 vs 7.0%, P=0.015, longer LOS (13.0 vs 9.0 days, P<0.001), but no significant difference in early or long-term mortality. Low but not high BMI was an independent predictor for 30-day mortality.

The results suggest that low BMI is associated with increased morbidity and mortality after CABG. Overweight is associated with more postoperative complications and longer hospitalisation but not with an increased early or long-term mortality.