Pediatric cardiomyopathy is a heterogeneous disease with high morbidity and mortality in which children often present with fulminant disease leading to death or transplant. Highly sensitive and specific cardiac biomarkers or panels of biomarkers, representing different pathologic mechanisms or pathways, are the least invasive (a particularly important consideration in children) and most-cost-effective approach to the early detection of cardiac dysfunction. The long-term goal of this project is to identify such biomarkers in children with cardiomyopathy. These findings could represent a major advance in determining the most appropriate evidence-based clinical care for these children, including when to consider heart transplantation.