Long-Term Follow-Up of Children and Adolescents Diagnosed with Hypertrophic Cardiomyopathy: Risk Factors for Adverse Arrhythmic Events

Our aim was to identify prognostic factors for an arrhythmic event (AE) in children with hypertrophic cardiomyopathy (HCM) without a previous AE. One hundred thirty-one nonconsecutive patients (a parts per thousand currency sign20 years) with HCM but no previous AE were evaluated at the NIH Clinical Center from 1980 to 2001. At a median follow-up of 6.4 years, 22 patients experienced an AE [sudden death (SD) (n = 12), resuscitated cardiac arrest (n = 3), clinical sustained ventricular tachycardia (VT) (n = 2), and implantable cardiac defibrillator discharge (n = 5)], resulting in a 2% annual AE rate. Baseline factors that were most predictive in univariate risk analysis included ventricular septal thickness (ST) (P = 0.01), VT induction by programmed ventricular stimulation (PVS) (P = 0.01), age (P = 0.05), and presyncope/syncope (P = 0.05). In multivariate analysis, ST, age, presyncope/syncope, and PVS were not independently predictive of risk for an AE. However, the 5-year event rates for AE was 15% (95% CI: 5-23%) if ST a parts per thousand yen 20 mm, 19% (95% CI: 6-31%) when age a parts per thousand yen 13 years and ST a parts per thousand yen 20 mm were combined together, and 23% (95% CI: 3-39%) when PVS and ST a parts per thousand yen 20 mm were combined together. Of the various risk factors that were considered in our pediatric HCM cohort, ST and inducible VT were the most significant univariate predictors of risk for an AE. More traditional risk factors identified in older patients (family history of SD, VT on Holter, and exercise-induced hypotension) were not predictive of an AE in patients age under 21 years.