Low‐ Versus High‐capacity Impella for CS After AMI: A Systematic Review and Pooled Data Analysis

BACKGROUND: Acute myocardial infarction with cardiogenic shock (AMI-CS) remains highly fatal despite advances in revascularization and intensive care. The Impella, a micro-axial pump, offers a potential balance of hemodynamic support and minimal invasiveness. AIMS: This study examined its optimal configuration of low- versus high-capacity for effectiveness and safety. METHODS: We conducted a systematic review and pooled analysis of 20 studies, including three randomized controlled trials (RCTs) and 3896 AMI-CS patients, comparing high-capacity (Impella 5.0/5.5) versus low-capacity (Impella 2.5/CP) devices. The primary outcome was in-hospital or 30-day mortality, with secondary endpoints including mortality on support, ischemic and bleeding complications, acute kidney injury requiring renal replacement therapy (RRT), and hemolysis. RESULTS: Among the included patients, 2022 received low-capacity Impella, while 771 received high-capacity Impella. The high-capacity Impella group demonstrated lower in-hospital or 30-day mortality (41.4% vs. 45.4%; p = 0.045) and significantly reduced mortality on support (17.9% vs. 46.1%; p < 0.001). Major bleeding events (1.4% vs. 6.0%; p < 0.001) and ischemic complications (3.9% vs. 5.9%; p = 0.05) were also lower in the high-capacity group. However, transfusion requirements were higher in the high-capacity Impella cohort (52.1% vs. 23.1%; p < 0.001). There were no significant differences in stroke rates (4.3% vs. 4.3%; p = 1.0) or AKI requiring RRT (36.5% vs. 34.9%; p = 0.69). CONCLUSION: High-capacity Impella, when compared to low-capacity devices, may provide superior survival benefits and lower complication rates, particularly in reducing ischemic and major bleeding events, in AMI-CS patients. These findings support the early consideration of high-capacity Impella in treatment algorithms.