Abstract 16525: Left Ventricular Unloading Before, Not After, Reperfusion Limits Infarct Size and Improves Survival in Acute Myocardial Infarction: A Bench to Bedside Study
Ischemia-reperfusion injury (IRI) is a major determinant of myocardial damage in acute myocardial infarction (AMI). We explored the hypothesis that reducing left ventricular wall stress (LV unloading) with an axial flow catheter (Impella) before, not after, coronary reperfusion reduces infarct size and improves survival.
Methods: We first employed a model of AMI. After 90 minutes of LAD occlusion, adult, male swine (n=4/group) were randomized to: 1) 120 minutes of reperfusion alone (IRI), 2) 30 minutes of LV unloading before 120 minutes of reperfusion (Impella to Balloon Group; ITB) or 3) 30 minutes of reperfusion followed by LV unloading and an additional 120 minutes of reperfusion (Balloon to Impella Group; BTI). Infarct size, myocardial kinase activity, and mitochondrial integrity were quantified. To explore the clinical utility of LV unloading before reperfusion we retrospectively studied all patients in the USPella registry presenting with ST-segmentc elevation AMI and cardiogenic shock who received an Impella within 120 minutes before (n=41; STEMI-ITB) or within 120 minutes after (n=76; STEMI-BTI) percutaneous reperfusion between 2009 and 2014.
Results: Compared to IRI alone, infarct size was reduced in the ITB group, not the BTI group (62±2% vs 33±6% vs 58±15%, IRI vs ITB vs BTI, p<0.01 for IRI vs ITB; p<0.05 for ITB vs BTI). Levels of phosphorylated Akt, Erk-1/2, and GSK3b were increased within the infarct zone in the ITB, not BTI group. Mitochondrial numbers and markers of integrity were higher within the infarct zone in the ITB, compared to IRI or BTI. In the registry, in-hospital (51% vs 28%, p=0.02) and 30-day survival (42% vs 20%, p=0.03) were higher in the STEMI-ITB than the STEMI-BTI group. A STEMI-ITB time of less than 60 minutes (n=38) was associated with higher in-hospital survival than a STEMI-BTI time of less than 60 minutes (n=40) (50% vs 25%, p=0.02).
Conclusion: Primary LV unloading before, not after, coronary reperfusion reduces infarct size, increases cardioprotective signaling, and improves mitochondrial integrity. These findings are supported by improved survival among patients treated with an Impella before, not after reperfusion in AMI. Future studies are required to explore the clinical utility of primary LV unloading in AMI.
Author Disclosures: N.K. Kapur: Research Grant; Significant; Abiomed, Maquet, Cardiac Assist. Speakers Bureau; Significant; Abiomed, Heartware, Maquet. Consultant/Advisory Board; Significant; Abiomed, Thoratec, Maquet, Cardiac Assist. V. Paruchuri: None. X. Qiao: None. K. Morine: None. L. Buiten: None. N. Josephy: Employment; Significant; Abiomed Inc. M. Hout: Employment; Significant; Abiomed Inc. R.H. Karas: None.
- © 2015 by American Heart Association, Inc.