title: Electrical storms in patients with an implantable cardioverter defibrillator.
abstract: OBJECTIVE
  In some patients with an implantable cardioverter defibrillator (ICD), multiple episodes of electrical storm (ES) can occur. We assessed the prevalence, features, and predictors of ES in patients with ICD.
  
  
  METHODS
  Eighty-five patients with an ICD were analyzed. ES was defined as the occurrence of two or more ventricular tachyarrhythmias within 24 hours.
  
  
  RESULTS
  Twenty-six patients experienced at least one ES episode, and 16 patients experienced two or more ES episodes. The first ES occurred 209 ± 277 days after ICD implantation. In most ES cases, the index arrhythmia was ventricular tachycardia (65%). There were no obvious etiologic factors at the onset of most ES episodes (57%). More patients with a structurally normal heart (p = 0.043) or ventricular fibrillation (VF) as the index arrhythmia (p = 0.017) were in the ES-free group. Kaplan-Meier estimates and a log-rank test showed that patients with nonischemic dilated cardiomyopathy (DCMP) (log-rank test, p = 0.016) or with left ventricular ejection fraction < 35% (p = 0.032) were more likely to experience ES, and that patients with VF (p = 0.047) were less affected by ES. Cox proportional hazard regression analysis showed that nonischemic DCMP correlated with a greater probability of ES (hazard ratio, 3.71; 95% confidence interval, 1.16-11.85; p = 0.027).
  
  
  CONCLUSIONS
  ES is a common and recurrent event in patients with an ICD. Nonischemic DCMP is an independent predictor of ES. Patients with VF or with a structurally normal heart are less likely to experience ES.
authors.affiliation: Division of Cardiology, Cardiac and Vascular Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Pil Sang
authors.initials: PS
authors.lastname: Song
authors.forename: June Soo
authors.initials: JS
authors.lastname: Kim
authors.forename: Dae-Hee
authors.initials: DH
authors.lastname: Shin
authors.forename: Jung Wae
authors.initials: JW
authors.lastname: Park
authors.forename: Ki In
authors.initials: KI
authors.lastname: Bae
authors.forename: Chang Hee
authors.initials: CH
authors.lastname: Lee
authors.forename: Dong Chae
authors.initials: DC
authors.lastname: Jung
authors.forename: Dong Ryeol
authors.initials: DR
authors.lastname: Ryu
authors.forename: Young Keun
authors.initials: YK
authors.lastname: On
mesh_terms: D000328:Adult; D000368:Aged; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000209:etiology; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000209:etiology