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Beyond Reperfusion: Acute Ventricular Unloading and Cardioprotection During Myocardial Infarction.

ABSTRACT: Heart failure is a major cause of morbidity and mortality around the world, and myocardial infarction is its leading cause. Myocardial infarction destroys viable myocardium, and this dead tissue is replaced by a non-contractile scar that results in impaired cardiac function and a significantly increased likelihood of the patient developing heart failure. Limiting infarct scar size has been the target of pre-clinical and clinical investigations for decades. However, beyond reperfusion, few therapies have translated into the clinic that limit its formation. New approaches are needed. This review will focus on new clinical and pre-clinical data demonstrating that acute ventricular unloading prior to reperfusion by means of percutaneous left ventricular support devices reduces ischemia-reperfusion injury and limits infarct scar size. Emphasis will be given to summarizing our current mechanistic understanding of this new therapeutic approach to treating myocardial infarction.

SUBMITTER: Curran J

PROVIDER: S-EPMC6497619 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Beyond Reperfusion: Acute Ventricular Unloading and Cardioprotection During Myocardial Infarction.

Curran Jerry J Burkhoff Daniel D Kloner Robert A RA

Journal of cardiovascular translational research 20190122 2

Heart failure is a major cause of morbidity and mortality around the world, and myocardial infarction is its leading cause. Myocardial infarction destroys viable myocardium, and this dead tissue is replaced by a non-contractile scar that results in impaired cardiac function and a significantly increased likelihood of the patient developing heart failure. Limiting infarct scar size has been the target of pre-clinical and clinical investigations for decades. However, beyond reperfusion, few therap ...[more]

PMID: 30671717

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Project description:BACKGROUND:Heart failure after an acute myocardial infarction (AMI) is a major cause of morbidity and mortality worldwide. We recently reported that activation of a transvalvular axial-flow pump in the left ventricle and delaying myocardial reperfusion, known as primary unloading, limits infarct size after AMI. The mechanisms underlying the cardioprotective benefit of primary unloading and whether the acute decrease in infarct size results in a durable reduction in LV scar and improves cardiac function remain unknown. OBJECTIVES:This study tested the importance of LV unloading before reperfusion, explored cardioprotective mechanisms, and determined the late-term impact of primary unloading on myocardial function. METHODS:Adult male swine were subjected to primary reperfusion or primary unloading after 90 min of percutaneous left anterior descending artery occlusion. RESULTS:Compared with primary reperfusion, 30 min of LV unloading was necessary and sufficient before reperfusion to limit infarct size 28 days after AMI. Compared with primary reperfusion, primary unloading increased expression of genes associated with cellular respiration and mitochondrial integrity within the infarct zone. Primary unloading for 30 min further reduced activity levels of proteases known to degrade the cardioprotective cytokine, stromal-derived factor (SDF)-1?, thereby increasing SDF-1? signaling via reperfusion injury salvage kinases, which limits apoptosis within the infarct zone. Inhibiting SDF-1? activity attenuated the cardioprotective effect of primary unloading. Twenty-eight days after AMI, primary unloading reduced LV scar size, improved cardiac function, and limited expression of biomarkers associated with heart failure and maladaptive remodeling. CONCLUSIONS:The authors report for the first time that first mechanically reducing LV work before coronary reperfusion with a transvalvular pump is necessary and sufficient to reduce infarct size and to activate a cardioprotective program that includes enhanced SDF-1? activity. Primary unloading further improved LV scar size and cardiac function 28 days after AMI.

Project description:Ischemic heart failure after acute myocardial infarction (AMI) is a major cause of morbidity and mortality worldwide. We recently reported that activation of a trans-valvular axial-flow pump in the LV and delaying myocardial reperfusion, known as Primary Unloading, limits infarct size by reducing LV wall stress and increasing expression of the cardioprotective cytokine, stromal derived factor 1 alpha (SDF1a). The mechanisms underlying the cardioprotective benefit and sustained effect of Primary Unloading remain poorly understood. We now tested the importance of delayed reperfusion, the functional significance of SDF1a, and the late-term impact on myocardial function and scar size associated with Primary Unloading. Adult male swine were subjected to Primary Reperfusion or Primary Unloading after 90 minutes of left anterior descending artery occlusion. Compared to Primary Reperfusion, 30 minutes of Primary Unloading was necessary and sufficient prior to reperfusion to limit infarct size. Primary Unloading was associated with a global shift in gene expression within the infarct zone favoring cardioprotection. Compared to Primary Reperfusion, Primary Unloading for 30 minutes preserved SDF1a protein levels without changing SDF1a mRNA levels within the infarct zone and further promoted a shift towards anti-apoptotic signaling within the infarct zone. Primary Unloading reduced activity levels of proteases known to degrade SDF1a and blocking the SDF1a receptor, CXCR4, attenuated the cardioprotective effect of Primary Unloading. Primary Unloading further reduced LV scar size, improved cardiac function, limited expression of markers associated with heart failure and maladaptive remodeling within the non-infarct zone 28 days after acute myocardial infarction. In conclusion, we introduce that Primary Unloading for 30 minutes before, not after reperfusion limits infarct size, increases SDF1a levels within the infarct zone, and results in a durable reduction in LV scar size, improved cardiac function, and limits markers of heart failure and maladaptive remodeling 28 days after AMI.

Project description:Patients with acute myocardial infarction (AMI) complicated by acute heart failure or cardiogenic shock have high mortality with conventional management.This study evaluated outcomes of patients with AMI who received durable ventricular assist devices (VAD).Patients in the INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) registry who underwent VAD placement in the setting of AMI were included and compared with patients who received VAD for non-AMI indications.VAD were implanted in 502 patients with AMI: 443 left ventricular assist devices; 33 biventricular assist devices; and 26 total artificial hearts. Median age was 58.3 years, and 77.1% were male. At implantation, 66% were INTERMACS profile 1. A higher proportion of AMI than non-AMI patients had pre-operative intra-aortic balloon pumps (57.6% vs. 25.3%; p < 0.01), intubation (58% vs. 8.3%; p < 0.01), extracorporeal membrane oxygenation (17.9% vs. 1.7%, p < 0.01), cardiac arrest (33.5% vs. 3.3%, p < 0.01), and higher-acuity INTERMACS profiles. At 1 month post-VAD, 91.8% of AMI patients were alive with ongoing device support, 7.2% had died on device, and 1% had been transplanted. At 1-year post-VAD, 52% of AMI patients were alive with ongoing device support, 25.7% had been transplanted, 1.6% had left VAD explanted for recovery, and 20.7% had died on device. The AMI group had higher unadjusted early phase hazard (hazard ratio [HR]: 1.24; p = 0.04) and reduced late-phase hazard of death (HR: 0.57; p = 0.04) than the non-AMI group did. After accounting for established risk factors, the AMI group no longer had higher early mortality hazard (HR: 0.89; p = 0.30), but it had lower late mortality hazard (HR: 0.55; p = 0.02).Patients with AMI who receive VAD have outcomes similar to other VAD populations, despite being more critically ill pre-implantation. VAD therapy is an effective strategy for patients with AMI and acute heart failure or shock in whom medical therapy is failing.

Dataset Information

Beyond Reperfusion: Acute Ventricular Unloading and Cardioprotection During Myocardial Infarction.

Publications

Beyond Reperfusion: Acute Ventricular Unloading and Cardioprotection During Myocardial Infarction.

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