title: Efficacy of implantable cardioverter defibrillators in young patients with catecholaminergic polymorphic ventricular tachycardia: success depends on substrate.
abstract: BACKGROUND
  The effectiveness of implantable cardioverter-defibrillator (ICD) therapy for the management of catecholaminergic polymorphic ventricular tachycardia (VT) in young patients is not known. ICD discharges are not always effective and inappropriate discharges are common, both resulting in morbidity and mortality.
  
  
  RESULTS
  This is a multicenter, retrospective review of young patients with catecholaminergic polymorphic VT and ICDs from 5 centers. ICD discharges were evaluated to determine arrhythmia mechanism, appropriateness, efficacy of therapy, and complications. A total of 24 patients were included. Median (interquartile range) ages at onset of catecholaminergic polymorphic VT symptoms and ICD implant were 10.6 (5.0-13.8) years and 13.7 (10.7-16.3) years, respectively. Fourteen patients received 140 shocks. Ten patients (42%) experienced 75 appropriate shocks and 11 patients (46%) received 65 inappropriate shocks. On actuarial analysis, freedom from appropriate shock at 1 year after ICD implant was 75%. Of appropriate shocks, only 43 (57%) demonstrated successful primary termination. All successful appropriate ICD discharges were for ventricular fibrillation. No episodes of polymorphic VT or bidirectional VT demonstrated successful primary termination. The adjusted mean (95% confidence interval) cycle length of successful discharges was significantly shorter than unsuccessful discharges (168 [152-184] ms versus 245 [229-262] ms; adjusted P=0.002). Electrical storm occurred in 29% (4/14) and induction of more malignant ventricular arrhythmias in 36% (5/14). There were no deaths.
  
  
  CONCLUSIONS
  ICD efficacy in catecholaminergic polymorphic VT depends on arrhythmia mechanism. Episodes of ventricular fibrillation were uniformly successfully treated, whereas polymorphic and bidirectional VT did not demonstrate successful primary termination. Inappropriate shocks, electrical storm, and ICD complications were common.
authors.affiliation: Department of Pediatrics, Lucile Packard Children's Hospital, Stanford University, Palo Alto, CA, USA. cymiyake@texaschildrens.org
authors.forename: Christina Y
authors.initials: CY
authors.lastname: Miyake
authors.forename: Gregory
authors.initials: G
authors.lastname: Webster
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Czosek
authors.forename: Michal J
authors.initials: MJ
authors.lastname: Kantoch
authors.forename: Anne M
authors.initials: AM
authors.lastname: Dubin
authors.forename: Kishor
authors.initials: K
authors.lastname: Avasarala
authors.forename: Joseph
authors.initials: J
authors.lastname: Atallah
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D002170:Canada; D002648:Child; D015331:Cohort Studies; D016001:Confidence Intervals; D017147:Defibrillators, Implantable; D004562:Electrocardiography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D010349:Patient Compliance; D012008:Recurrence; D012189:Retrospective Studies; D018570:Risk Assessment; D018709:Statistics, Nonparametric; D015996:Survival Rate; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000188:drug therapy / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D016896:Treatment Outcome; D014481:United States; D055815:Young Adult; D000098850:Polymorphic Catecholaminergic Ventricular Tachycardia
chemical_list: D000889:Anti-Arrhythmia Agents
keywords: arrhythmia; catecholaminergic polymorphic ventricular tachycardia; electrical storm; implanted cardioverter defibrillator; pediatric; ventricular tachycardia