Impact of body mass index on long-term mortality after coronary artery bypass grafting: a retrospective cohort study

Objectives: The obesity paradox in cardiac surgery suggests that obesity may be protective and associated with better survival after surgery. The aim of this study was to assess the impact of patients’ body mass index (BMI) on late mortality after isolated coronary artery bypass grafting (CABG). Methods: All consecutive patients who underwent isolated CABG at our institution from 2014 to 2020 were included. Patients were divided into four groups according to (BMI): underweight (BMI <20.0 kg/m 2 ), normal weight (BMI 20.0–24.9 kg/m 2 ), overweight (BMI, 25–30 kg/m 2 ), and obese (BMI > 30 kg/m 2 ). The long-term mortality was analyzed as primary end-point. The univariable and multivariable analysis was performed using Cox regression modeling. Results: The study population consisted of 6448 patients including 104 (1.6%), 1296 (20.1%), 2946 (45.7%), and 2102 (32.6%) in the consecutive study groups. Mean follow-up time was 4.69 ± 2.17 years. Overall 30-day mortality was 2.5%. Univariable analysis showed survival benefit in all patients with increased weight in comparison to normal weight group; with HR 0.776, 95% CI 0.675–0.891, P < 0.001 in the overweight, and HR 0.767, 95% CI 0.661–0.890, P < 0.001 in the obese patients group. Multivariable analysis revealed better survival in both overweight and obese patients in comparison to normal weight group (HR 0.836, 95% CI 0.727–0.961, P = 0.012, and HR 0.854, 95% CI 0.734–0.994, P = 0.042, respectively). Conclusions: Increased weight is associated with better long-term survival in patients after CABG, both in the overweight and obese patients