Should obese patients undergo on- or off-pump coronary artery bypass grafting?

OBJECTIVES: To determine if on- or off-pump coronary artery bypass grafting (CABG) makes a difference to in-hospital mortality and long-term survival in obese patients.

METHODS: Analysis of consecutive patients on a validated prospective cardiac surgery database was performed for patients undergoing isolated CABG. Obesity was defined as a body mass index (BMI) >30 kg/m(2). Uni- and multivariate analyses were performed for in-hospital mortality and long-term survival. A propensity analysis was also performed.

RESULTS: The overall mortality rate was 2.1% (N = 284) for all cases, N = 13 369. The mortality rate for obese patients (N = 4289) was 2.3%, and for non-obese patients (N = 9080) it was 2.0%; P = 0.4. The median follow-up was 7.0 (interquartile range 4.1-10.1) years. Univariate analysis identified that in-hospital mortality was significantly lower in obese patients undergoing off-pump CABG; P = 0.01. No significant difference existed with regard to non-obese patients; P = 0.55. Kaplan-Meier survival analysis identified that off-pump CABG was associated with improved survival in obese patients; P = 0.01. Multivariate analysis of non-obese patients did not identify on- or off-pump CABG as a significant factor determining in-hospital mortality or long-term survival. Multivariate analysis of obese patients identified off-pump CABG as being associated with significantly reduced in-hospital mortality (odds ratio [OR] 0.56, 95% confidence interval [CI] 0.34-0.93, P = 0.03), and significantly improved long-term survival (hazard ratio 0.81, 95% CI 0.67-0.98, P = 0.03). In-hospital mortality and long-term survival were significantly affected by the era of surgery, regardless of patients' BMI. Propensity matching of non-obese patients (N = 6088, 1:1 matching) did not identify on- or off-pump CABG as a significant factor determining in-hospital mortality or long-term survival. Propensity matching of obese patients (N = 2980, 1:1 matching) identified on-pump CABG as a significant factor determining in-hospital mortality (OR 0.50, 95% CI 0.26-0.98, P = 0.04), but having no effect on long-term survival.

CONCLUSIONS: Univariate, multivariate and propensity matching suggest that obese patients undergoing CABG have reduced in-hospital mortality if they undergo revascularization with the off-pump technique.