title: Safety and efficacy of advanced atrial pacing therapies for atrial tachyarrhythmias in patients with a new implantable dual chamber cardioverter-defibrillator.
abstract: OBJECTIVE
  This study evaluated the safety and efficacy of atrial pacing therapies for the treatment and prevention of atrial tachycardia (AT) or atrial fibrillation (AF) in a new dual chamber implantable cardioverter defibrillator (ICD).
  
  
  BACKGROUND
  Patients with an ICD may also experience AT or AF that is amenable to pace termination.
  
  
  METHODS
  The efficacy of atrial antitachycardia pacing (ATP) therapies for atrial tachycardia or atrial fibrillation (AT/AF) was determined in 151 patients after implantation of a GEM III AT ICD (Medtronic Inc., Minneapolis, Minnesota). The percentage of episodes successfully terminated was adjusted for multiple episodes per patient.
  
  
  RESULTS
  A total of 717 of 728 (96%) episodes classified as AT or AF were judged to be appropriate detections. By device classification, atrial ATP terminated 187 of 383 (40% adjusted) episodes classified as AT compared with 65 of 240 episodes classified as AF (26% adjusted, p = 0.013). Atrial Ramp or Burst+ ATP terminated 184 of 378 episodes of AT (39% adjusted), whereas 50-Hz Burst pacing therapy terminated only 12 of 109 episodes of AT (12% adjusted) and 65 of 240 episodes of AF (26% adjusted). If efficacy was defined as termination of AT/AF within 20 s of delivery of the pacing therapy, ATP therapies terminated 139 of 383 (32% adjusted) episodes of AT compared with 34 of 240 episodes of AF (15% adjusted, p = 0.003). Efficacy was dependent on AT cycle length. Frequent transitions between AT and AF predicted inefficacy of atrial ATP (p < 0.001). Ventricular proarrhythmia secondary to atrial ATP was not observed.
  
  
  CONCLUSIONS
  Atrial ATP therapies terminate many episodes of AT without ventricular proarrhythmia. The addition of 50-Hz Burst pacing has minimal efficacy for AT/AF.
authors.affiliation: Foothills Hospital and the division of Cardiology, University of Calgary, 3330 Hospital Drive Northwest, Calgary, Alberta, Canada T2N 4N1. amgillis@ucalgary.ca
authors.forename: Anne M
authors.initials: AM
authors.lastname: Gillis
authors.forename: Christina
authors.initials: C
authors.lastname: Unterberg-Buchwald
authors.forename: Herwig
authors.initials: H
authors.lastname: Schmidinger
authors.forename: Santini
authors.initials: S
authors.lastname: Massimo
authors.forename: Kevin
authors.initials: K
authors.lastname: Wolfe
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Kavaney
authors.forename: Mary F
authors.initials: MF
authors.lastname: Otterness
authors.forename: Stefan H
authors.initials: SH
authors.lastname: Hohnloser
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects / Q000379:methods*; D017147:Defibrillators, Implantable / Q000009:adverse effects; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D013610:Tachycardia / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome