Obesity and the risk of early and late mortality after coronary artery bypass graft surgery

Abstract

Background Obesity is often considered to be a significant risk factor for postoperative mortality when selecting candidates for coronary artery bypass grafting (CABG). Methods We included all patients undergoing a first isolated CABG at the Karolinska Hospital in Stockholm, Sweden, between 1980 and 1995 (n = 6728). Patients were categorized on the basis of body mass index (BMI): non-overweight (BMI <25 kg/m 2), overweight (25 kg/m 2 ≤ BMI <30 kg/m 2), and obese (BMI ≥30 kg/m 2). Multivariate Cox regression was used to assess the risk of re-operation for bleeding, deep sternal wound infection, and early (≤30 days) and late (≤5 years) mortality rates. Results The average length of follow-up was 6.5 years. There were 252 re-operations for bleeding, 53 deep sternal wound infections, and 628 deaths. Patients who were obese had a significantly lower risk of re-operation for bleeding (risk ratio [RR], 0.32; 95% CI, 0.19–0.53), but a greater risk of deep sternal wound infection (RR, 2.66; 95% CI, 1.21–5.88) compared with patients who were not overweight. However, patients who were obese and patients who were not overweight experienced similar 30-day (RR, 0.65; 95% CI, 0.34–1.27), 1-year (RR, 0.56; 95% CI, 0.29–1.10), and 5-year mortality rates (RR, 0.91; 95% CI, 0.66–1.25). Results for patients who were overweight were consistent with those of patients who were obese. Conclusion Patients who are obese are not at a greater risk of early and late mortality after CABG compared with patients who are not overweight, although they appear to have a lower risk of re-operation for bleeding and a greater risk of deep sternal wound infection. Therefore, obesity per se is not a contraindication for CABG.