title: Electrical storm in patients with transvenous implantable cardioverter-defibrillators: incidence, management and prognostic implications.
abstract: OBJECTIVE
  The purpose of this study was to determine the precise incidence, therapeutic options and prognostic implications of electrical storm in patients with transvenous implantable cardioverter-defibrillator (ICD) systems.
  
  
  BACKGROUND
  Approximately 50% to 70% of patients treated with an ICD receive appropriate device-based therapy within the first 2 years. Most arrhythmic events require only one appropriate ICD firing for termination. However, some patients receive multiple appropriate shocks during a short period of time, a condition referred to as "arrhythmic or electrical storm."
  
  
  METHODS
  This prospectively designed observational study comprised 136 recipients of transvenous ICDs who were followed for 403+/-242 days. Electrical storm was defined as ventricular tachycardia or fibrillation resulting in device intervention > or = 3 times during a single 24-h period.
  
  
  RESULTS
  During follow-up, 57/136 patients (42%) received appropriate ICD therapy. Electrical storm occurred in 14/136 patients (10%) at an average of 133+/-135 days after ICD implantation. The mean number of arrhythmic episodes constituting electrical storm was 17+/-17 (range: 3 to 50; median 8) per patient. In 12 patients, electrical storm required hospital admission. The arrhythmia cluster could be terminated by a combined therapy with beta-blockers and intravenous amiodarone whereas class I antiarrhythmic drugs were only occasionally successful. The cumulative probability of survival as estimated by the Kaplan-Meier method showed that patients with an episode of electrical storm did not have a worse outcome compared to those without such an event.
  
  
  CONCLUSIONS
  Electrical storm represents a frequent event in patients treated with modern ICDs. It occurs most commonly late after ICD implantation and can be managed by combined therapy with beta-blockers and amiodarone. Electrical storm does not independently confer increased mortality.
authors.affiliation: Department of Internal Medicine, JW Goethe University, Frankfurt, Germany.
authors.forename: S C
authors.initials: SC
authors.lastname: Credner
authors.forename: T
authors.initials: T
authors.lastname: Klingenheben
authors.forename: O
authors.initials: O
authors.lastname: Mauss
authors.forename: C
authors.initials: C
authors.lastname: Sticherling
authors.forename: S H
authors.initials: SH
authors.lastname: Hohnloser
mesh_terms: D000328:Adult; D000368:Aged; D017704:Baroreflex; D017147:Defibrillators, Implantable; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012008:Recurrence; D017180:Tachycardia, Ventricular / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000503:physiopathology / Q000628:therapy*