SHOCK3: Comparing Veno-arterial Extracorpeal Membrane Oxygenation (VA-ECMO) vs. VA-ECMO plus Impella (ECPELLA) on Mortality in Patients with Cardiac Arrest After an Acute Myocardial Infarction (AMI)

Abstract

Background: More than 800,000 people suffer from an AMI in the United States every year. One of the most feared complications of an AMI is cardiac arrest, and even if return of spontaneous circulation is achieved, profound cardiogenic shock (CS) is a common sequalae. VA-ECMO is utilized to support patients with CS, and now more frequently, used in conjunction with an Impella to off-load the left ventricle, though a paucity of evidence supports this practice. The goal of this study was to determine whether a mortality difference was observed in VA-ECMO alone vs ECPELLA in patients with CS after cardiac arrest secondary to an AMI. Methods: A dual-center, retrospective chart review of 52 patients who suffered cardiac arrest from an AMI and were supported with VA-ECMO or ECPELLA was performed. Univariable comparisons consisting of baseline demographics, cardiac arrest data, catheterization laboratory reports and intensive care unit (ICU) data were compared between the two groups using chi-squared analysis, independent t-test, and Wilcoxon Rank Sum Test to determine statistical significance. Cox proportional hazard models were constructed to test the independent association between treatment groups and mortality, controlling for various acute physiology and post-cardiac arrest prognostic scores. Results: Thirty-four patients received VA-ECMO only, and 16 patients were supported with an ECPELLA strategy. Ninety-day mortality was 67.6% in the VA-ECMO group, and 87.5% in the ECPELLA group. There was no statistically significant difference between the groups within regards to mortality (Hazard Ratio (HR): 1.69, 95% confidence interval 0.86-3.30). This remained true even when adjusting for the following validated prognostic scores: Simplified Acute Physiology Score II (SAPS), Survival after veno-arterial ECMO (SAVE), modified SAVE, Cardshock, and Charlson Comorbidity index. There we no differences in baseline demographic data nor ICU complications between the groups. Patients who experienced a ST elevated myocardial infarction (STEMI) were more likely to be in the VA-ECMO group rather than the ECPELLA group (p=0.044). Conclusion: Our results found no significant differences in mortality in patients with CS after cardiac arrest secondary to an AMI when treated with VA-ECMO vs ECPELLA. It should be highlighted that the study population was only 52 patients, thus the power of the study was significantly limited. Therefore, more experience and broader collaboration/data sharing is needed to identify if ECPELLA is a beneficial acute cardiac support strategy in this patient population.Figure 1. VA-ECMO vs ECPELLA Survival Curve