Impella in cardiogenic shock following acute myocardial infarction: a systematic review and meta-analysis

Cardiogenic shock (CS) conveys a high mortality risk. A cardiac assist device may serve as bridge to patient recovery. We aimed to provide a pooled estimate on mortality and complications from studies evaluating the use of the left ventricular assist device Impella in CS following acute myocardial infarction. In addition, we evaluated whether mortality risk differed with device placement before or after percutaneous coronary intervention (PCI).

We searched Medline, Embase and Web of Science from 2005 until July 2019 for observational studies or clinical trials on this specific patient group. Studies were required to report on 30-day all-cause mortality and device-related complications. We calculated pooled proportions with 95% confidence intervals (CI) using random effects models and the inverse variance method.

Overall, 671 patients from 11 studies (2 randomized and 9 observational) were included. Pooled proportions showed a 30-day mortality of 54.6% (95% CI 47.3-61.8; P = 0.22; I² = 65.8%). Among complications, major bleeding was found in 19.9% (95% CI 14.2-27.3; P < 0.05; I² = 69.1%), hemolysis in 10.5% (95% CI 7.2-15.0; P < 0.05; I² = 52.1%), limb ischemia in 5.0% (95% CI 2.6-9.5; P < 0.05; I² = 48.3%) and stroke in 3.8% of patients (95% CI 2.4-5.9; P < 0.05; I² = 0%). Sensitivity analysis demonstrated a statistically significant risk reduction in 30-day mortality when Impella was implanted prior to PCI as compared to after PCI, risk ratio (RR): 0.71, CI 0.58-0.86, P = 0.001, I² = 0%.

Pooled estimates of Impella use in myocardial infarction with CS revealed a high 30-day mortality; however, as compared to post-PCI, Impella initiation prior to PCI was associated with a survival benefit.