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Prevention of Sudden Cardiac Death With Implantable Cardioverter-Defibrillators in Children and Adolescents With Hypertrophic Cardiomyopathy
Study Questions:
What is the efficacy of implantable cardioverter-defibrillators (ICDs) in children and adolescents with hypertrophic cardiomyopathy (HCM)?
Methods:
A multicenter international registry was created of pediatric patients with HCM undergoing device implantation between 1987 and 2011. A total of 224 children and adolescents with HCM judged to be at high risk for sudden death were included in the registry. ICDs were placed for primary prevention in 188 patients and secondary prevention in 36 patients.
Results:
Appropriate activation of defibrillators to terminate ventricular tachycardia occurred in 43 (19%) patients over a mean of 4.3 ± 3.3 years. The ICD intervention rate for devices placed for secondary prevention was 14% per year as compared with 3.1% for devices placed for primary prevention. There was no difference in discharge rate for ventricular tachycardia or fibrillation based on number of risk factors for patients with devices for primary prevention. The most common risk factor present for patients receiving appropriate therapies was extreme left ventricular hypertrophy. ICD-related complications occurred in 91 (41%) patients. Sixty-three patients (28%; 6.5% per year) experienced inappropriate shocks, whereas an additional 28 patients (12%) experienced other significant device-related complications. One patient died suddenly when a defective ICD failed to defibrillate a lethal arrhythmia.
Conclusions:
The authors concluded that ICDs are effective in terminating life-threatening ventricular tachyarrhythmias in high-risk pediatric patients with HCM, but are associated with a high rate of device complications.
Perspective:
This registry-based study investigated the efficacy of ICDs in the prevention of sudden cardiac death in pediatric patients with HCM. In the registry, device placement was at the discretion of the treating pediatric cardiologist and electrophysiologist. High-risk features guiding device placement included family history of premature HCM-related sudden death, extreme left ventricular hypertrophy, unexplained syncope inconsistent with neurocardiogenic syncope, nonsustained ventricular tachycardia (≥3 beats ≥120/minute), and hypotensive response to exercise. As patients were selected for these high-risk features, the study may not apply to the general population of pediatric patients with HCM. Importantly, the number of risk factors was not important in predicted appropriate device therapies, with 50% of appropriate therapies occurring in patients with only one risk factor. Device-related complication rates were high, occurring at a greater rate (9%) than appropriate interventions (3%) for the cohort undergoing device placement for primary prevention.
Keywords: Hypertrophy, Left Ventricular, Heart Defects, Congenital, Heart Conduction System, Cardiomyopathy, Hypertrophic, Electric Countershock, Syncope, Risk Factors, Primary Prevention, Child, Registries, Tachycardia, Ventricular, Secondary Prevention, Defibrillators, Implantable, Death, Sudden, Cardiac
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