title: Arrhythmia characterization and long-term outcomes in catecholaminergic polymorphic ventricular tachycardia.
abstract: BACKGROUND
  Catecholaminergic polymorphic ventricular tachycardia (CPVT) is characterized by adrenergically induced ventricular tachycardia (VT) associated with syncope and sudden death.
  
  
  OBJECTIVE
  This study sought to characterize arrhythmias associated with CPVT with respect to provocation by exercise and drugs, electrocardiographic characteristics, and association with long-term outcomes; and to explore the relation between age and clinical presentation.
  
  
  METHODS
  Seventy patients from 16 families were evaluated with exercise and selective adrenaline challenge, and screened for RyR2 mutations. CPVT was diagnosed in probands with symptoms and stress- or adrenaline-provoked VT, or in asymptomatic relatives with provoked VT or RyR2 mutations. Patients were followed up for recurrent syncope, VT, and sudden death.
  
  
  RESULTS
  Twenty-seven patients including 16 probands were identified (median age 35 years, 67% female). Presentation was cardiac arrest in 33% and syncope in 56%, and 11% were asymptomatic. Polymorphic or bidirectional VT was provoked with exercise in 63% and adrenaline in 82%. The initiating beat of VT was late-coupled and wide (coupling interval 418 ± 42 ms; QRSd 131 ± 17 ms), and QRS morphology suggested an outflow tract origin in 59%. During follow-up of 6.2 ± 5.7 years, 2 patients died despite an implantable cardioverter-defibrillator (ICD), 4 patients received ICD therapy for VT, and 5 patients had inappropriate therapy for supraventricular tachycardia. Patients presenting with late-onset CPVT (age > 21; n = 10) were often female (80%) and less likely to have RyR2 (Ryanodine receptor type 2) mutations (33%), and fatal events were not observed during follow-up (4.1 ± 3.6 years).
  
  
  CONCLUSIONS
  Ventricular arrhythmia in CPVT is often initiated from the outflow tract region. Despite β-blocker therapy and selective ICD implantation, breakthrough arrhythmias occur and may be associated with adverse outcomes.
authors.affiliation: University of Western Ontario, Ontario, Canada.
authors.forename: Raymond W
authors.initials: RW
authors.lastname: Sy
authors.forename: Michael H
authors.initials: MH
authors.lastname: Gollob
authors.forename: George J
authors.initials: GJ
authors.lastname: Klein
authors.forename: Raymond
authors.initials: R
authors.lastname: Yee
authors.forename: Allan C
authors.initials: AC
authors.lastname: Skanes
authors.forename: Lorne J
authors.initials: LJ
authors.lastname: Gula
authors.forename: Peter
authors.initials: P
authors.lastname: Leong-Sit
authors.forename: Robert M
authors.initials: RM
authors.lastname: Gow
authors.forename: Martin S
authors.initials: MS
authors.lastname: Green
authors.forename: David H
authors.initials: DH
authors.lastname: Birnie
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Krahn
mesh_terms: D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D002395:Catecholamines / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D004247:DNA / Q000235:genetics*; D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009864:Ontario / Q000453:epidemiology; D012307:Risk Factors; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics*; D015996:Survival Rate / Q000639:trends; D013575:Syncope / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D017180:Tachycardia, Ventricular / Q000150:complications / Q000235:genetics* / Q000378:metabolism; D013997:Time Factors; D055815:Young Adult; D000098850:Polymorphic Catecholaminergic Ventricular Tachycardia
chemical_list: D000319:Adrenergic beta-Antagonists; D002395:Catecholamines; D019837:Ryanodine Receptor Calcium Release Channel; D004247:DNA