title: Tachyarrhythmia Cycle Length in Appropriate versus Inappropriate Defibrillator Shocks in Brugada Syndrome, Early Repolarization Syndrome, or Idiopathic Ventricular Fibrillation.
abstract: OBJECTIVE
  Implantable cardioverter-defibrillators (ICDs) are indicated in patients with Brugada syndrome (BS), early repolarization syndrome (ERS), or idiopathic ventricular fibrillation (IVF) who are at high risk for sudden cardiac death. The optimal ICD programming for reducing inappropriate shocks in these patients remains to be determined. We investigated the difference in the mean cycle length of tachyarrhythmias that activated either appropriate or inappropriate ICD shocks in these three patient groups to determine the optimal ventricular fibrillation (VF) zone for minimizing inappropriate ICD shocks.
  
  
  METHODS
  We selected 41 patients (35 men) (mean age±standard deviation=42.6±13.0 year) who received ICD shocks between April 1996 and April 2014 to treat BS (n=24), ERS (n=9), or IVF (n=8). Clinical and ICD interrogation data were retrospectively collected and analyzed for all events with ICD shocks.
  
  
  RESULTS
  Of the 244 episodes, 180 (73.8%) shocks were appropriate and 64 (26.2%) were inappropriate. The mean cycle lengths of the tachyarrhythmias that activated appropriate and inappropriate shocks were 178.9±28.7 ms and 284.8±24.4 ms, respectively (p<0.001). The cutoff value with the highest sensitivity and specificity for discriminating between appropriate and inappropriate shocks was 235 ms (sensitivity, 98.4%; specificity, 95.6%). When we programmed a single VF zone of ≤270 ms, inappropriate ICD shocks were reduced by 70.5% and appropriate shocks were missed in 1.7% of these patients.
  
  
  CONCLUSIONS
  Programming of a single VF zone of ≤270 ms in patients with BS, ERS, or IVF could reduce inappropriate ICD shocks, with a low risk of missing appropriate shocks.
authors.affiliation: Division of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Woo Seok
authors.initials: WS
authors.lastname: Lee
authors.affiliation: Division of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jun
authors.initials: J
authors.lastname: Kim
authors.affiliation: Division of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Chang-Hee
authors.initials: CH
authors.lastname: Kwon
authors.affiliation: Division of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Choi
authors.affiliation: Division of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Uk
authors.initials: U
authors.lastname: Jo
authors.affiliation: Division of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Yoo Ri
authors.initials: YR
authors.lastname: Kim
authors.affiliation: Division of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Gi-Byoung
authors.initials: GB
authors.lastname: Nam
authors.affiliation: Division of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Kee-Joon
authors.initials: KJ
authors.lastname: Choi
authors.affiliation: Division of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: You-Ho
authors.initials: YH
authors.lastname: Kim
keywords: Brugada syndrome; Cardioverter defibrillator, implantable; Ventricular fibrillation