Left Ventricular Unloading With Impella Versus IABP in Patients With VA-ECMO: A Systematic Review and Meta-Analysis.

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) use for circulatory support in cardiogenic shock results in increased left ventricular (LV) afterload. The use of concomitant Impella or intra-aortic balloon pump (IABP) have been proposed as adjunct devices for LV unloading. The authors sought to compare head-to-head efficacy and safety outcomes between the 2 LV unloading strategies. We conducted a search of Medline, EMBASE, and Cochrane databases to identify studies comparing the use of Impella to IABP in patients on VA-ECMO. The primary outcome of interest was in-hospital mortality. The secondary outcomes included transition to durable LV assist devices/cardiac transplantation, stroke, limb ischemia, need for continuous renal replacement therapy, major bleeding, and hemolysis. Pooled risk ratios (RRs) with 95% confidence interval and heterogeneity statistic I 2 were calculated using a random-effects model. A total of 7 observational studies with 698 patients were included. Patients on VA-ECMO unloaded with Impella vs IABP had similar risk of short-term all-cause mortality, defined as either 30-day or in-hospital mortality- 60.8% vs 64.9% (RR 0.93 [0.71 to 1.21], I 2  = 71%). No significant difference was observed in transition to durable LV assist devices/cardiac transplantation, continuous renal replacement therapy initiation, stroke, or limb ischemia between the 2 strategies. However, the use of VA-ECMO with Impella was associated with increased risk of major bleeding (57.2% vs 39.7%) (RR 1.66 [1.12 to 2.44], I 2  = 82%) and hemolysis (31% vs 7%) (RR 4.61 [1.24 to 17.17], I2 = 66%) compared with VA-ECMO, along with IABP. In conclusion, in patients requiring VA-ECMO for circulatory support, the concomitant use of Impella or IABP had comparable short-term mortality. However, Impella use was associated with increased risk of major bleeding and hemolysis.