VA-ECMO-Related Complications Seem not Causally Related to Mortality in Patients with Acute Myocardial Infarction Complicated by Cardiogenic Shock

T. Thevathasan (Berlin)¹, A. Freund (Leipzig)², U. Zeymer (Ludwigshafen am Rhein)³, J. Pöss (Leipzig)², T. Ouarrak (Ludwigshafen am Rhein)⁴, S. Schneider (Ludwigshafen am Rhein)⁵, H. Thiele (Leipzig)², S. Desch (Leipzig)^2
1Charité - Universitätsmedizin Berlin CC 11: Med. Klinik für Kardiologie Berlin, Deutschland; ²Herzzentrum Leipzig - Universität Leipzig Klinik für Innere Medizin/Kardiologie Leipzig, Deutschland; ³Institut für Herzinfarktforschung Ludwigshafen am Rhein, Deutschland; ⁴IHF GmbH Institut für Herzinfarktforschung, Ludwigshafen am Rhein, Deutschland IHF GmbH Institut für Herzinfarktforschung, Ludwigshafen am Rhein, Deutschland Ludwigshafen am Rhein, Deutschland; ⁵IHF GmbH Ludwigshafen am Rhein, Deutschland

Background: Recent randomised controlled trials, along with a meta-analysis of individual patient data, have demonstrated that the routine application of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) does not confer a survival benefit over standard medical therapy in patients experiencing acute myocardial infarction complicated by cardiogenic shock (AMI-CS). 
Purpose: This study sought to determine whether potential complications specifically associated with VA-ECMO might contribute to an elevated risk of mortality, possibly explaining the similar mortality outcomes observed between patients receiving VA-ECMO and those managed with conventional therapy in cases of AMI-CS.
Methods: Data was sourced from the ECLS-SHOCK trial, a randomised study comparing routine VA-ECMO implementation to medical therapy alone in infarct-related cardiogenic shock. The study employed causal mediation analyses, using VA-ECMO-related complications as a mediator in primary analyses, alongside logistic regression and analyses of death causality as secondary analyses. These analyses examined the impact of VA-ECMO-related complications on 30-day mortality, with adjustments made for bleeding and vascular complication risk factors.
Results: This analysis included a total of 417 patients. VA-ECMO-related complications were identified, particularly moderate to severe bleeding and peripheral vascular complications necessitating intervention. Out of the study population, 88 patients (21.1%) experienced complications likely attributable to VA-ECMO, predominantly within five days post-randomisation, with higher occurrences in the VA-ECMO group compared to the control group: bleeding in 49 (23.4%) vs. 20 (9.6%) patients, p<0.001, and peripheral vascular complications in 23 (11.0%) vs. 8 (3.8%) patients, p=0.01. However, causal mediation analyses indicated no significant mediating effect of VA-ECMO-related complications on 30-day mortality (p=n.s.; Figure). Logistic regression and mortality causality analyses similarly identified no significant correlation between the presence of VA-ECMO-related complications and mortality (p=n.s.).
Conclusion: In patients with AMI-CS, VA-ECMO use was linked to increased incidences of moderate to severe bleeding and intervention-requiring vascular complications. This causal mediation analysis suggests that VA-ECMO-related complications do not directly contribute to an elevated mortality risk.