Efficacy of Mechanical Circulatory Support Used Before Versus After Primary Percutaneous Coronary Intervention in Patients with Cardiogenic Shock From ST-Elevation Myocardial Infarction: A Systematic Review and Meta-Analysis.

BACKGROUND: Optimal timing to initiate mechanical circulatory support (MCS) in patients with ST-elevation myocardial infarction (STEMI) complicated by cardiogenic shock (CS) remains unclear with studies showing conflicting results on whether to start before or after primary percutaneous coronary intervention (PPCI). This study aims to examine the association between mortality and MCS initiated before vs after PPCI in patients with STEMI complicated by CS. METHODS: We systematically searched PubMed, Embase, and Scopus for abstracts and full-text articles from inception to October 2021. Studies were included if they evaluated the association of mortality in patients who initiated MCS (specifically intra-aortic balloon pump (IABP), Impella, and venoarterial extracorporeal membrane oxygenation (VA-ECMO)) before PPCI versus after PPCI, specifically in patients with STEMI complicated by CS. Data were integrated using the random-effects models. RESULTS: Ten studies involving 1,352 patients (956, 203, and 193 patients underwent IABP, Impella, and VA-ECMO respectively) with STEMI complicated by CS were included. There was no difference in mortality using IABP before or after PPCI ([OR] 1.77, 95% CI 0.77-1.61, I2 = 27%, p = 0.57). Nevertheless, Impella and VA-ECMO started before PPCI were significantly associated with a reduced risk of mortality compared to that started after PPCI ([OR] 0.49, 95% CI 0.26-0.92, I2 = 0%, p = 0.03 and [OR] 0.29, 95% CI 0.14-0.62, I2 = 0%, p = 0.001, respectively). CONCLUSIONS: In patients with STEMI complicated by CS undergoing PPCI, the use of IMPELLA or VA-ECMO prior to PPCI significantly decreased mortality, in contrast to IABP, in which no difference in mortality was found between using it before or after PPCI. More rigorous studies are needed to clarify this association.