Abstract 17383: Total Left Ventricular Unloading with Impella® during Ischemia Reperfusion Minimizes Infarct Size, Preserves Left Ventricular Function and Prevents Chronic Heart Failure

Background: Despite marked advances of revascularization, acute myocardial infarction (MI) remains a major cause of chronic heart failure (CHF). Since excessive oxygen demand relative to supply is the fundamental mechanism of ischemia, we previously demonstrated, using a conventional left ventricular assist device (VAD), that total left ventricular (LV) unloading markedly reduced the MI size in ischemia reperfusion (IR) model through minimizing the myocardial oxygen consumption in acute experiment. The purpose of this investigation was to examine if the transvascular VAD, Impella®, could totally unload LV during IR and preserve LV function in chronic phase. Methods: We allocated 15 dogs into 3 groups, Sham (n=4), IR (n=6) and IR+Impella® (n=5). In IR and IR+Impella®, we ligated the left anterior descending artery for 180min through a left thoracotomy and then reperfused. In IR+Impella®, we introduced Impella® through the left subclavian artery from 60 min after the beginning of ischemia to 90 min after reperfusion. We then assessed LV function and MI size 4 weeks after IR injury. Results: Under Impella® support, LV pressure was much lower than arterial pressure indicating total LV unloading. In comparison with IR, Impella® significantly improved LV ejection fraction (2D-echo, Fig) (Sham 64±2.8, IR 48±3.1, IR+Impella® 64±1.2%, p=0.0007), lowered LVEDP (Sham 5.9±1.1, IR 16±3.7, IR+Impella® 4.3±0.87mmHg, p<0.05) and increased end-systolic elastance (sonomicrometric volumetry) (Sham 11±3.1, IR 5.7±1.5, IR+Impella® 12±1.6 mmHg/ml, p<0.05). Furthermore, Impella markedly reduced MI size (%LV circumferential area, IR 18±9.2, IR+Impella® 2.1±0.76%, p=0.0044, Fig) and decreased NT-proBNP (Sham 1004±462, IR 3385±677, IR+Impella® 1463±217pg/ml). Conclusions: Total LV unloading during IR with Impella® strikingly reduces MI size and preserves LV function in chronic phase. Impella® is a powerful tool in the management of acute MI in preventing CHF.