NRG1 and heart failure: Despite the documented beneficial role of Nrgs in cardiac function, circulating Nrg1 level was associated with heart failure severity,11 which did not correlate with the ability to repair damaged myocardium.77 In this regard, our study made an important finding that administration of rhNrg1 before ischemic insult protects myocardium while introduction of rhNrg1 postischemic stress aggravated MI.