Mechanical left ventricular unloading in cardiogenic shock treated with venoarterial extracorporeal membrane oxygenation: a systematic review and meta-analysis

Objective To evaluate if mechanical left ventricular unloading could reduce mortality in patients with cardiogenic shock undergoing venoarterial extracorporeal membrane oxygenation (VA-ECMO). Methods We searched MEDLINE, Embase, and the Cochrane Library for randomized controlled trials and propensity score-matched studies published until December 20, 2023. The primary outcome was mortality at the longest follow-up. We used a Mantel-Haenszel random effects meta-analysis and reported the pooled results with a risk ratio (RR) and 95% confidence interval (CI). The review protocol was registered on PROSPERO International prospective register of systematic review (CRD42024498665). Results We identified two randomized controlled trials and eleven propensity score-matched studies, totaling 9858 patients. Mechanical left ventricular unloading was significantly associated with reduced mortality at the longest follow-up (RR, 0.89; 95% CI, 0.84-0.94; P = 0.0001; moderate certainty of evidence), which was confirmed in studies using intraaortic ballon pump (IABP). Benefits of mechanical unloading were also observed in terms of successful VA-ECMO weaning (RR, 1.15; 95% CI, 1.02-1.29; P = 0.02; low certainty of evidence) and favorable neurological outcome (two studies; RR, 2.45; 95% CI, 1.62-3.69; P < 0.0001; low certainty of evidence), although we observed an increased incidence of major bleeding (RR, 1.27; 95% CI, 1.02-1.59; P = 0.03; low certainty of evidence) and hemolysis (RR, 1.49; 95% CI, 1.10-2.02; P = 0.01; moderate certainty of evidence). Conclusions Among adult patients with cardiogenic shock treated with VA-ECMO, mechanical left ventricular unloading was associated with reduced mortality, which was confirmed in studies using IABP as an unloading device.