Risk factors and mode of death in isolated hypertrophic cardiomyopathy in children.

OBJECTIVES: This study was designed to review outcomes of pediatric isolated hypertrophic cardiomyopathy (HCM) managed uniformly at a single institution and assess whether reported adult risk factors for sudden death are predictive in pediatric HCM.

BACKGROUND: Cardiac death in HCM occurs suddenly (SCD) or may be nonsudden (non-SCD). Little data exists on non-SCD in children. Risk factors for SCD in adult HCM are characterized and consensus management strategies detailed. Their application to children is uncertain and treatment strategies vary.

METHODS: A retrospective cohort study of children with HCM was performed. Primary end points were cardiac death and transplantation. Frequency and outcomes of known adult risk factors were assessed. Outcomes analysis was performed using Kaplan-Meier curves and Cox regression analysis.

RESULTS: Ninety-six patients were included. The average age at diagnosis was 10.6 +/- 5.4 years, and mean follow-up was 6.4 +/- 5.2 years. Primary end points occurred in 11 patients over the 20-year follow-up (11%), 4 underwent cardiac transplant and 7 died (3 suddenly). Extreme left ventricular hypertrophy (z-score: >6) and an abnormal blood pressure response to exercise were predictive of non-SCD (p < 0.02 and p < 0.03, respectively). Kaplan-Meier survival analysis predicts an 82% survival over a 20-year period.

CONCLUSIONS: In children with isolated HCM managed primarily with exercise restriction and medication, cardiac death occurred infrequently. Non-SCD or transplant was at least as common as SCD. Extreme left ventricular hypertrophy and blunted blood pressure response to exercise were associated with an increased risk of non-SCD.