Abstract 2552: Hypertrophic Cardiomyopathy in Children: Do Adult Risk Factors for Cardiac Death Apply

Introduction : Annual mortality in children with hypertrophic cardiomyopathy (HCM) has been reported to be 1– 6%. Risk factors for death in adult HCM patients have been characterized; their application to pediatric HCM is unknown. The purpose of this study was to correlate adult risk factors with outcomes in our pediatric population using a standard management strategy. Methods : A retrospective cohort study of children with HCM was performed. Death and cardiac transplant were the primary outcomes. Diagnosis was based on asymmetric septal or concentric hypertrophy as determined by echocardiography. Exclusion criteria included: genetic syndrome, mitochondrial or metabolic disorder, infants of diabetic mothers, congenital heart disease, systemic hypertension, diagnosis >18 years of age, or follow-up <1 year. Results : From 1/1/85 to 10/1/06, 96 patients met inclusion criteria. Mean age at diagnosis was 10.6 ± 5.4 years. Mean follow-up was 6.5 ± 5.2 years. 11 patients had an adverse outcome (7 deaths, 4 transplants). Kaplan-Meier analysis predicts an 82% survival over 20 years. Evidence of left ventricular outflow tract obstruction (LVOTO) occurred in =6% of patients, syncope in 23% and a family history for malignant HCM in 17%. Aborted sudden death occurred in 6%. 10% had non-sustained ventricular tachycardia. 58% of patients underwent at least one exercise treadmill test. All patients were restricted from strenuous activity. 95% of patients were on a β-blocker or calcium channel blocker, with 10% on both. Additional intervention depended on symptoms, family history, and degree of LVOTO. 17% had an implantable defibrillator (ICD). 10% were given a pacemaker due to LVOTO, and 5% underwent left ventricular myectomy. Only extreme LVH (>6 z-scores for BSA) and a blunted blood pressure response to exercise were statistically significant for worse outcomes (both p<0.02). Conclusions : A low mortality/transplantation rate occurred in children with isolated HCM whose management consisted of exercise restriction and medication, with or without an ICD. Management that included myectomy was uncommon. Patients with extreme LVH and a blunted blood pressure response to exercise are high-risk individuals.