title: Prevention of sudden cardiac death with implantable cardioverter-defibrillators in children and adolescents with hypertrophic cardiomyopathy.
abstract: OBJECTIVE
  The aim of this study was to determine the efficacy of implantable cardioverter-defibrillators (ICDs) in children and adolescents with hypertrophic cardiomyopathy (HCM).
  
  
  BACKGROUND
  HCM is the most common cause of sudden death in the young. The availability of ICDs over the past decade for HCM has demonstrated the potential for sudden death prevention, predominantly in adult patients.
  
  
  METHODS
  A multicenter international registry of ICDs implanted (1987 to 2011) in 224 unrelated children and adolescents with HCM judged at high risk for sudden death was assembled. Patients received ICDs for primary (n = 188) or secondary (n = 36) prevention after undergoing evaluation at 22 referral and nonreferral institutions in the United States, Canada, Europe, and Australia.
  
  
  RESULTS
  Defibrillators were activated appropriately to terminate ventricular tachycardia or ventricular fibrillation in 43 of 224 patients (19%) over a mean of 4.3 ± 3.3 years. ICD intervention rates were 4.5% per year overall, 14.0% per year for secondary prevention after cardiac arrest, and 3.1% per year for primary prevention on the basis of risk factors (5-year cumulative probability 17%). The mean time from implantation to first appropriate discharge was 2.9 ± 2.7 years (range to 8.6 years). The primary prevention discharge rate terminating ventricular tachycardia or ventricular fibrillation was the same in patients who underwent implantation for 1, 2, or ≥3 risk factors (12 of 88 [14%], 10 of 71 [14%], and 4 of 29 [14%], respectively, p = 1.00). Extreme left ventricular hypertrophy was the most common risk factor present (alone or in combination with other markers) in patients experiencing primary prevention interventions (17 of 26 [65%]). ICD-related complications, particularly inappropriate shocks and lead malfunction, occurred in 91 patients (41%) at 17 ± 5 years of age.
  
  
  CONCLUSIONS
  In a high-risk pediatric HCM cohort, ICD interventions terminating life-threatening ventricular tachyarrhythmias were frequent. Extreme left ventricular hypertrophy was most frequently associated with appropriate interventions. The rate of device complications adds a measure of complexity to ICD decisions in this age group.
authors.affiliation: Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation, Minneapolis, MN 55407, USA. hcm.maron@mhif.org
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Maron
authors.forename: Paolo
authors.initials: P
authors.lastname: Spirito
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ackerman
authors.forename: Susan A
authors.initials: SA
authors.lastname: Casey
authors.forename: Christopher
authors.initials: C
authors.lastname: Semsarian
authors.forename: N A Mark
authors.initials: NA
authors.lastname: Estes
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Shannon
authors.forename: Euan A
authors.initials: EA
authors.lastname: Ashley
authors.forename: Sharlene M
authors.initials: SM
authors.lastname: Day
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pacileo
authors.forename: Francesco
authors.initials: F
authors.lastname: Formisano
authors.forename: Emmanuela
authors.initials: E
authors.lastname: Devoto
authors.forename: Aristidis
authors.initials: A
authors.lastname: Anastasakis
authors.forename: J Martijn
authors.initials: JM
authors.lastname: Bos
authors.forename: Anna
authors.initials: A
authors.lastname: Woo
authors.forename: Camillo
authors.initials: C
authors.lastname: Autore
authors.forename: Robert H
authors.initials: RH
authors.lastname: Pass
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Boriani
authors.forename: Ross F
authors.initials: RF
authors.lastname: Garberich
authors.forename: Adrian K
authors.initials: AK
authors.lastname: Almquist
authors.forename: Mark W
authors.initials: MW
authors.lastname: Russell
authors.forename: Luca
authors.initials: L
authors.lastname: Boni
authors.forename: Stuart
authors.initials: S
authors.lastname: Berger
authors.forename: Martin S
authors.initials: MS
authors.lastname: Maron
authors.forename: Mark S
authors.initials: MS
authors.lastname: Link
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001315:Australia; D002170:Canada; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy*; D002423:Cause of Death; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D016001:Confidence Intervals; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D004562:Electrocardiography / Q000379:methods; D005060:Europe; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D016016:Proportional Hazards Models; D012042:Registries; D018570:Risk Assessment; D012720:Severity of Illness Index; D012737:Sex Factors; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States