Strategies of left ventricular unloading during VA-ECMO support: a network meta-analysis

Background: Left ventricle (LV) unloading during VenoArterial ExtraCorporeal Membrane Oxygenation (VA-ECMO) reduces the risk of LV distention, stagnation and pulmonary congestion resulting from the increased afterload. Lacking direct comparisons between unloading strategies we used network meta-analysis to indirectly compare different unloading approaches. Methods: A literature research was performed to include all studies on VA-ECMO reporting data on mechanical LV unloading. The pre-specified outcome was in-hospital death. Results: Literature search identified 389 studies: 16 were included in the analysis (3930 patients). Two strategies of mechanical LV unloading were compared: afterload reduction (IABP) and preload reduction (Impella pump, right upper pulmonary/trans-septal catheters, LV surgical vents). Any LV unloading strategy was associated with mortality reduction with overall OR = 0.54; 95% CI 0.42–0.70; p < .001. Targeting afterload was associated with reduced mortality (OR = 0.61 95% CI 0.46–0.81; p < .001; I2 = 61%), as targeting preload (OR = 0.34 95% CI 0.21–0.55; p < .001; I2 = 0%). Significant between group difference was observed (p = .04): to further explore this we performed a network meta-analysis. Indirect comparisons between afterload and preload reduction were estimated. Any unloading technique was confirmed better than none but preload targeting resulted better than afterload targeting. Conclusion: Any unloading strategy in VA-ECMO patients was associated with lower mortality as compared to no-unloading. Preload reduction strategies resulted superior to afterload reduction.