Identification of Risk Factors for Arrhythmia in Children and Adolescents With Hypertrophic Cardiomyopathy

This study will review medical information collected on children and adolescents with hypertrophic cardiomyopathy (HCM) to try to identify risk factors for arrhythmias (abnormal heart rhythms) in these patients and better guide the choice of treatment options for them. Arrhythmias arising from the ventricle (lower heart chamber) can cause dizziness, fainting or cardiac arrest. Predictors of arrhythmias in adult HCM patients may not apply to children and teenagers with HCM. Children and adolescents 21 years of age or younger who were diagnosed with HCM and evaluated in the National Heart Lung and Blood Institute's Cardiology Branch between 1977 and 2002 may be eligible for this study. Participants do not undergo any further testing or data gathering beyond a review of their medical records; only existing data previously collected for research purposes are used. Medical records are reviewed for age of the patient on admission to the NIH; family history of sudden death, fainting, exercise-induced low blood pressure, and results of tests on heart structure and function.