Left Ventricular Unloading Using Intra-aortic Entrainment Pumping Before Reperfusion Reduces Post-AMI Infarct Size

BACKGROUND: Anterior myocardial infarction standard of care prioritizes swift coronary reperfusion. Recent studies show left ventricular (LV) unloading with transvalvular axial flow pumps for 30 minutes before reperfusion (vs immediate reperfusion) decreases 28-day infarct size. Intra-aortic entrainment pumping, using hardware located away from the heart to provide support throughout the cardiac cycle, decreases effective systemic vascular resistance and augments visceral blood flow and pressure, and may reproduce this benefit with a decreased risk. This study characterized the hemodynamic effects of unloading before and during reperfusion using intra-aortic entrainment pumping and investigated whether unloading decreased anterior myocardial infarction scar size. METHODS AND RESULTS: Yorkshire swine were subjected to 90 minutes of left anterior descending artery balloon occlusion and randomly assigned to immediate reperfusion (n = 6) vs 30 minutes unloading before reperfusion followed by 120 minutes of further unloading (n = 7). Unloading was achieved using percutaneous entrainment pumping in the descending aorta. The anterior myocardial infarction model matches that used in recent transvalvular pumping studies. Mortality before randomization was 22%. After randomization, mortality was 36% for immediate reperfusion and 0% for unloading. Unloading showed immediate hemodynamic benefit that increased through reperfusion and continued support, leading to distinct differences in cardiac function between groups after 30 minutes of reperfusion. Unloading increased stroke volume and cardiac efficiency at this timepoint relative to preocclusion baseline and reduced 28-day LV scar size by 37%-45%. CONCLUSIONS: We present the first preclinical data showing extracardiac LV unloading before coronary reperfusion using intra-aortic entrainment pumping decreases 28-day infarct size. Extracardiac unloading to decrease LV scar size may provide an alternative to transvalvular pumping with potential advantages, including reduced risk.