title: Optimizing implantable cardioverter-defibrillator treatment of rapid ventricular tachycardia: antitachycardia pacing therapy during charging.
abstract: BACKGROUND
  Previous studies in implantable cardioverter-defibrillator (ICD) patients demonstrated the efficacy and safety of antitachycardia pacing (ATP) for rapid ventricular tachycardias (VT). To prevent shock delay in case of ATP failure, a new feature (ATP during charging) was developed to deliver ATP for rapid VT while charging for shock.
  
  
  OBJECTIVE
  The purpose of this study was to determine the efficacy and safety of this new feature.
  
  
  METHODS
  In a prospective, nonrandomized trial, patients with standard ICD indication received an EnTrust ICD. VT and ventricular fibrillation (VF) episodes were reviewed for appropriate detection, ATP success, rhythm acceleration, and related symptoms.
  
  
  RESULTS
  In 421 implanted patients, 116 VF episodes occurred in 37 patients. Eighty-four (72%) episodes received ATP during or before charging. ATP prevented a shock in 58 (69%) of 84 episodes in 15 patients. ATP stopped significantly more monomorphic (77%) than polymorphic VTs (44%, P = .05). Five (6%) episodes accelerated after ATP but were terminated by the backup shock(s). No symptoms were related to ATP during charging. In four patients, 38 charges were saved by delivering ATP before charging. Of 98 induced VF episodes, 28% were successfully terminated by ATP versus 69% for spontaneous episodes (P <.01).
  
  
  CONCLUSIONS
  Most VTs detected in the VF zone can be painlessly terminated by ATP delivered during charging, with a low risk of acceleration or symptoms. ATP before charging allows delivery of two ATP attempts before shock in the same time that would otherwise be required to deliver only one ATP plus a shock. It also offers potential battery energy savings.
authors.affiliation: Evangelisches und Johanniter Klinikum Niederrhein GmbH, Herzzentrum Duisburg, Klinik für Kardiologie und Angiologie, Duisburg, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schoels
authors.forename: David
authors.initials: D
authors.lastname: Steinhaus
authors.forename: W Ben
authors.initials: WB
authors.lastname: Johnson
authors.forename: Gilles
authors.initials: G
authors.lastname: O'hara
authors.forename: Joerg O
authors.initials: JO
authors.lastname: Schwab
authors.forename: Inge
authors.initials: I
authors.lastname: Jenniskens
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Degroot
authors.forename: Feng
authors.initials: F
authors.lastname: Tang
authors.forename: Erhard
authors.initials: E
authors.lastname: Helmling
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D017147:Defibrillators, Implantable; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000628:therapy*