The Relation between Obesity and Mortality in Postcardiotomy Veno-arterial Membrane Oxygenation

Background: Obesity is an important health problem in cardiac surgery and among patients requiring post-cardiotomy veno-arterial extracorporeal membrane oxygenation (V-A ECMO). Still, it remains unclear whether these patients are at risk for unfavorable outcomes after post-cardiotomy V-A ECMO. The current study aimed to evaluate the association between body mass index (BMI and in-hospital outcomes in this setting. Methods: The Post-cardiotomy Extracorporeal Life Support (PELS-1)-study is an international, multi-center study. Patients requiring post-cardiotomy V-A ECMO in 36 centers from 16 countries between 2000-2020 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, secondary outcomes included major adverse events. Mixed logistic regression models were applied to evaluate associations between BMI and mortality. Results: The study cohort included 2046 patients (median age 65 years, n=838 females (41.0%). In-hospital mortality was 60.3%, without statistically significant differences among BMI classes for in-hospital mortality or major adverse events (p=0.225 and p=0.126). The crude association between BMI and in-hospital mortality was not statistically significant after adjustment for comorbidities and intra-operative variables (Class I odds ratio [OR] 1.21 95% confidence interval [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. Conclusions: BMI is not associated to in-hospital outcomes adjustment for confounders in patients undergoing post-cardiotomy V-A ECMO. Therefore, BMI itself should not be incorporated in the risk stratification for PC V-A ECMO.