Work

The impact of low body mass index on clinical outcomes after coronary artery bypass graft surgery

Year: 2025

Type: article

Abstract: Objective To clarify the effects of being underweight on clinical outcomes after coronary artery bypass grafting (CABG) and possible associated sex differences. Methods The study population included 5914 patients who underwent their first isolated CABG; patients with acute myocardial infarction were excluded. Clinical outcomes within and beyond 30 days after CABG were compared across groups on the basis of preoperative body mass index (BMI): underweight (BMI <18.5; n=318), normal (18.5 ≤ BMI < 25; n=3835), overweight (25 ≤ BMI < 30; n=1580), and obese (BMI ≥30; n=181). Results The cumulative 30-day incidence of all-cause death was 3.2%, 1.2%, 0.4%, and 1.1% in the underweight, normal, overweight, and obese groups, respectively (log-rank P < .001). This trend was more prominent in men than in women (4.0%, 1.3%, 0.4%, and 1.6%, log-rank P < .001; 1.7%, 0.9%, 1.1%, and 0.0%, log-rank P = .74). The cumulative 5-year incidence of all-cause death >30 days after CABG was significantly greater in the underweight group (27.1%, 16.6%, 10.1%, and 6.5%; log-rank P < .001). The greater risk of being underweight and the lower risk of being overweight or obese relative to normal were significant for all-cause death (adjusted hazard ratio, 1.22 [95% confidence interval, 1.00-1.49]; 0.77 [0.68-0.89]; and 0.63 [0.42-0.95], respectively). Furthermore, the excess mortality risk of being underweight relative to normal was significant in men (1.32 [1.03-1.68]) but not in women (1.14 [0.80-1.63]) (interaction P = .01). Conclusions Being underweight was associated with increased short- and long-term mortality after CABG, especially in men, whereas being overweight or obese was associated with decreased long-term mortality after CABG.

Source: JTCVS Open

DOI: 10.1016/j.xjon.2025.08.003