The effects of obesity on mortality following coronary artery bypass graft surgery: A retrospective study from a single center in China

Background: Coronary artery bypass graft (CABG) surgery has become a routine surgical procedure for patients with occlusive coronary artery atherosclerosis. Worldwide, increasing levels of obesity are associated with ischemic heart disease and systemic comorbidities. This retrospective study from a single center in China aimed to investigate the effects of obesity on patient mortality following CABG surgery. Material/Methods: Patients undergoing CABG (N=1471) were grouped according to body mass index (BMI) as normal weight (N=596), overweight (N=684), or obese (N=191). Baseline clinical characteristics and outcomes were recorded. Logistic regression analysis was performed for 30-day postoperative mortality. Kaplan-Meier survival curves were plotted, and Cox regression analysis investigated risk and protective factors for long-term mortality, with subgroup analysis for differences between on-pump and off-pump CABG groups. Results: The 30-day postoperative mortality was 5.0% in the normal-weight group, 1.3% in the overweight group, and 0% in the obese group. BMI was an independent protective factor for 30-day postoperative mortality (odds ratio=0.748; 95% confidence interval, 0.640-0.874; P<0.001). The 10-year mortality for the groups was 13.2% (normal), 7.8% (overweight), and 12.7% (obese). The >20-year mortality rates for the groups were 33.0% (normal), 41.5% (overweight), and 12.7% (obese). There was no significant correlation between BMI and long-term mortality. Being overweight had a protective effect against long-term mortality in the off-pump CABG subgroup. Conclusions: An “obesity paradox” was identified in postoperative outcomes in patients following CABG surgery, with an increased BMI associated with reduced 30-day postoperative mortality. This association was more significant in the off-pump CABG group.