Sex differences in venoarterial extracorporeal membrane oxygenation utilisation and clinical outcomes in Australia

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is increasingly utilised in critically ill patients with severe cardiac failure and cardiac arrest, yet sex-specific differences in presentation, utilisation, and clinical outcomes are not well understood.

The EXCEL registry is a binational registry capturing data on patients requiring ECMO in Australia and New Zealand. Data were collected on adult patients supported with VA-ECMO in Australia from February 2019 to December 2024. Patients were stratified by sex to assess differences in demographics, clinical characteristics, ECMO indications, complications, and outcomes. Multivariable logistic regression analyses conditional on several baseline covariates assessed associations between sex, in-hospital mortality, and major bleeding.

Among 1443 patients undergoing VA-ECMO, 32.7% female and 67.3% were male. Females were younger, had lower APACHE IV scores, and more commonly required ECMO for myocarditis, pulmonary embolism, and advanced pulmonary hypertension. Conversely, males predominantly presented with acute myocardial infarction and more frequently had cardiac arrest with a shockable rhythm. Unadjusted in-hospital mortality was comparable between sexes; however, following adjustment, female sex independently predicted higher in-hospital mortality (OR 1.41, 95% CI 1.07-1.87; p = 0.015) and major bleeding (OR 1.40, 95% CI 1.03-1.91; p = 0.033).

Female patients represent one third of the VA-ECMO population and are a distinct cohort to male patients. Despite younger age and fewer traditional risk factors, female sex is associated with increased adjusted risk of in-hospital mortality and bleeding in VA-ECMO patients. These findings should be interpreted as an adjusted association that is contingent on the completeness of covariate adjustment.