Obesity is an important health problem in cardiac surgery and among patients requiring postcardiotomy venoarterial extracorporeal membrane oxygenation (V-A ECMO). Still, whether these patients are at risk for unfavorable outcomes after postcardiotomy V-A ECMO remains unclear. The current study evaluated the association between body mass index (BMI) and in-hospital outcomes in this setting.

The Post-cardiotomy Extracorporeal Life Support (PELS-1) study is an international, multicenter study. Patients requiring postcardiotomy V-A ECMO in 36 centers from 16 countries between 2000 and 2020 were included. Patients were divided in 6 BMI categories (underweight, normal weight, overweight, class I, class II, and class III obesity) according to international recommendations. Primary outcome was in-hospital mortality, and secondary outcomes included major adverse events. Mixed logistic regression models were applied to evaluate associations between BMI and mortality.

The study cohort included 2046 patients (median age, 65 years; 838 women [41.0%]). In-hospital mortality was 60.3%, without statistically significant differences among BMI classes for in-hospital mortality (P = .225) or major adverse events (P = .126). The crude association between BMI and in-hospital mortality was not statistically significant after adjustment for comorbidities and intraoperative variables (class I: odds ratio [OR], 1.21; 95% CI, 0.88-1.65; class II: OR, 1.45; 95% CI, 0.86-2.45; class III: OR, 1.43; 95% CI, 0.62-3.33), which was confirmed in multiple sensitivity analyses.

BMI is not associated to in-hospital outcomes after adjustment for confounders in patients undergoing postcardiotomy V-A ECMO. Therefore, BMI itself should not be incorporated in the risk stratification for postcardiotomy V-A ECMO.