Mechanical circulatory support with Impella versus intra-aortic balloon pump or medical treatment in cardiogenic shock—a critical appraisal of current data

Patients suffering from cardiogenic shock (CS) have a high mortality and morbidity. The Impella percutaneous left-ventricular assist device (LVAD) decreases LV preload, increases cardiac output, and improves coronary blood flow. We aimed to review and meta-analyze available data comparing Impella versus intra-aortic pump (IABP) counterpulsation or medical treatment in CS due to acute myocardial infarction or post-cardiac arrest. Study-level data were analyzed. Heterogeneity was assessed using the I2 statistic. Risk rates were calculated and obtained using a random-effects model (DerSimonian and Laird). Four studies were found suitable for the final analysis, including 588 patients. Primary endpoint was short-term mortality (in-hospital or 30-day mortality). In a meta-analysis of four studies comparing Impella versus control, Impella was not associated with improved short-term mortality (in-hospital or 30-day mortality; RR 0.84; 95% CI 0.57–1.24; p = 0.38; I2 55%). Stroke risk was not increased (RR 1.00; 95% CI 0.36–2.81; p = 1.00; I22 0%), but risk for major bleeding (RR 3.11 95% CI 1.50–6.44; p = 0.002; I2 0%) and peripheral ischemia complications (RR 2.58; 95% CI 1.24–5.34; p = 0.01; I2 0%) were increased in the Impella group. In patients suffering from severe CS due to AMI, the use of Impella is not associated with improved short-time survival but with higher complications rates compared to IABP and medical treatment. Better patient selection avoiding Impella implantation in futile situations or in possible lower risk CS might be necessary to elucidate possible advantages of Impella in future studies.