In children, DCM is a diverse disorder with outcomes that depend largely on cause, age, and heart failure status at presentation. Race, sex, and age affect the incidence of disease. Most children do not have a known cause of DCM, which limits the potential for disease-specific therapies.

Background-Current information on the epidemiology and outcomes of hypertrophic cardiomyopathy (HCM) in children is limited by disease diversity and small case series. Methods and Results-The Pediatric Cardiomyopathy Registry has collected prospective and retrospective data on children diagnosed with HCM since 1990. We identified the various causes of HCM in childhood and determined the relationship between outcomes, cause, and age at presentation. Of 855 patients Ͻ18 years of age with HCM, 8.7% (nϭ74) had inborn errors of metabolism, 9.0% (nϭ77) had malformation syndromes, 7.5% (nϭ64) had neuromuscular disorders, and 74.2% (nϭ634) had idiopathic HCM. Children with HCM associated with inborn errors of metabolism and malformation syndromes have significantly worse survival than the other 2 groups. Patients with idiopathic HCM diagnosed before 1 year of age (nϭ227) had worse survival from the time of diagnosis than those diagnosed after 1 year of age (nϭ407). Patients with idiopathic HCM who survived to at least 1 year of age, however, had an annual mortality rate of 1% that was similar regardless of whether they were diagnosed before or after 1 year of age. Conclusions-In children, HCM is a diverse disorder with outcomes that depend largely on cause and age. Patients presenting before 1 year of age have the broadest spectrum of causes and the poorest outcome. In those children with idiopathic HCM who survive beyond age 1, however, survival is independent of age at diagnosis, with an annual mortality rate (1%) that is much lower than previously reported in children and is not different from has been found in population-based studies in adults.

The estimated incidence of pediatric cardiomyopathy in two large regions of the United States is 1.13 cases per 100,000 children. Most cases are identified at an early age, and the incidence varies according to sex, region, and racial or ethnic origin.

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