Venoarterial extracorporeal membrane oxygenation (VA-ECMO) with vs. without left ventricular unloading by Impella: a systematic review and meta-analysis

Background and aims: The use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) for the treatment of cardiogenic shock (CS) may result in left ventricle overload and distension. Percutaneous microaxial flow pump Impella in addition to VA-ECMO (ECPELLA) is an emerging option to overcome these collateral effects. Aim of this study is to assess whether the addition of Impella to VA-ECMO is an effective and safe unloading strategy. Methods and results: We performed a systematic literature review of studies comparing ECPELLA vs. ECMO alone in patients with CS. The primary endpoint was early mortality (in-hospital or 30-day mortality). The secondary endpoints were bleeding, need for kidney replacement therapy, haemolysis, infections, and limb ischaemia. A total of 3469 potentially relevant articles were screened and eight retrospective studies including 11.137 patients were selected. There was no significant difference in early mortality (Risk Ratio, RR 0.90, 95% CI 0.78-1.03) between ECPELLA and ECMO. Nevertheless, there was a borderline significant reduction in early mortality with ECPELLA (RR 0.74, 95% CI 0.55-1.00) at sensitivity analysis selectively including studies reporting propensity matched analysis. ECPELLA was associated with increased bleeding (RR 1.45, 95% CI 1.20-1.75), need for kidney replacement therapy (RR 1.54, 95% CI 1.19-1.99), haemolysis (RR 1.71, 95% CI 1.41-2.07) and limb ischaemia (RR 1.43, 95% CI 1.17-1.75) and with a non-significant increase in severe infections (RR 1.26, 95% CI 0.84-1.89), compared with ECMO alone. Conclusion: Among patients with cardiogenic shock, ECPELLA is associated with increased complications compared with ECMO. Whether reducing ventricular overload with Impella among patients treated with ECMO reduces early mortality needs to be confirmed by further investigations.