title: Electrical storm in patients with an implantable defibrillator: incidence, features, and preventive therapy: insights from a randomized trial.
abstract: OBJECTIVE
  The purpose of this study was to assess the incidence, features, and clinical sequelae of 'electrical storm' (ES).
  
  
  RESULTS
  This study is a prospectively designed secondary analysis of SHIELD; a randomized trial of azimilide for suppression of ventricular tachycardia/fibrillation (VT/VF) leading to implanted cardioverter defibrillator (ICD) therapies. Systematic and rigorous follow-up and blinded adjudication of ICD therapy allowed identification of all ESs (>/=3 separate VT/VF episodes leading to ICD therapies within 24 h). Of 633 ICD recipients, 148 (23%) experienced at least one ES over 1-year follow-up. No clinical predictors of ES were identified. Frequent VT episodes accounted for 91% of all ESs, with the remaining being VF alone or both VT plus VF. ES led to a 3.1-fold increase in arrhythmia-related hospitalization (95% CI 2.3-4.3; P<0.0001) compared with patients with isolated VT/VF, and to a 10.2-fold increase (95% CI 6.4-16.3; P<0.0001) compared with patients without VT/VF. Compared with placebo, azimilide (75 and 125 mg/day) reduced the risk of recurrent ES by 37% (HR=0.63, 95% CI 0.35-1.11, P=0.11) and 55% (HR=0.45, 95% CI 0.23-0.87, P=0.018), respectively. However, the reduction in time-to-first ES did not reach statistical significance by both doses (75 and 125 mg) of azimilide (HR=0.82, 95% CI 0.56-1.19, P=0.29 and HR=0.69, 95% CI 0.46-1.04, P=0.07), respectively.
  
  
  CONCLUSIONS
  ES is common and unpredictable in ICD recipients and it is a strong predictor of hospitalization.
authors.affiliation: Division of Electrophysiology, Department of Cardiology, J.W. Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany. hohnloser@em.uni-frankfurt.de
authors.forename: Stefan H
authors.initials: SH
authors.lastname: Hohnloser
authors.forename: Hussein R
authors.initials: HR
authors.lastname: Al-Khalidi
authors.forename: Craig M
authors.initials: CM
authors.lastname: Pratt
authors.forename: Jose M
authors.initials: JM
authors.lastname: Brum
authors.forename: Daljit S
authors.initials: DS
authors.lastname: Tatla
authors.forename: Patrick
authors.initials: P
authors.lastname: Tchou
authors.forename: Paul
authors.initials: P
authors.lastname: Dorian
mesh_terms: D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D015331:Cohort Studies; D017147:Defibrillators, Implantable; D005260:Female; D006801:Humans; D006827:Hydantoins; D048289:Imidazolidines / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000627:therapeutic use*; D011446:Prospective Studies; D017180:Tachycardia, Ventricular / Q000517:prevention & control / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D000889:Anti-Arrhythmia Agents; D002121:Calcium Channel Blockers; D006827:Hydantoins; D048289:Imidazolidines; D010879:Piperazines; C086123:azimilide