Measuring myocardial salvage: hormone cardioprotection

Ischemic heart disease (IHD) is the leading cause of death and disability worldwide. For patients presenting with an acute ST-segment elevation myocardial infarction (STEMI) the treatment of choice is timely reperfusion by primary percutaneous coronary intervention (PPCI). However, the process of reperfusion can in itself independently induce myocardial injury and cardiomyocyte death—a phenomenon that has been termed “myocardial reperfusion injury” and that contributes to up to 50% of the final myocardial infarction (MI) size. Therefore, novel cardioprotective therapies are required to protect the heart against myocardial reperfusion injury in order to reduce MI size, preserve myocardial function, and prevent the onset of heart failure. In this regard, a number of hormones have been reported in preclinical animal studies and early clinical trials to reduce MI size when administered at the time of reperfusion. Assessing the cardioprotective efficacy of a novel therapy requires the measurement of the area at risk (AAR) of MI and MI size, as this allows the calculation of myocardial salvage, which is a more sensitive measure of cardioprotection than absolute MI size reduction as it takes into account the AAR. Cardiac magnetic resonance imaging (MRI) is an important imaging modality for assessing myocardial salvage in reperfused STEMI patients. The recent availability of hybrid simultaneous positron emission tomography (PET)/MRI will allow one to investigate the effects of novel cardioprotective therapies in the reperfused heart on cardiac metabolism, fibrosis, angiogenesis, apoptosis, and inflammation, providing new insights into the pathophysiology of acute MI and the post-MI remodeled heart. In this article, we review the emerging role of cardiac MRI to assess myocardial salvage of novel cardioprotective therapies such as hormones. L Heart Metab. 2015;66:13-18