title: Impact of accelerated ventricular tachyarrhythmias on mortality in patients with implantable cardioverter-defibrillator therapy.
abstract: BACKGROUND
  Anti-tachycardia pacing (ATP) and shock delivery may induce or accelerate tachyarrhythmias in patients with implantable cardioverter-defibrillator (ICD). We investigated the incidence, triggers and impact on mortality of accelerated ventricular tachyarrhythmias.
  
  
  METHODS
  Database analysis concerning ventricular tachyarrhythmias accelerated by ATP or shock in 1275 ICD patients (age at implantation 59.7 ± 14.0 years; 81% male).
  
  
  RESULTS
  Within a mean follow-up period of 5.3 ± 4.0 years, intracardiac electrograms were available in 1170 patients (91.8%). Overall 157 episodes of accelerated ventricular tachyarrhythmias were found in 100 of 1170 patients (8.5%). Termination of tachyarrhythmias was achieved by shock delivery in 153 episodes (96.8%). Triggers of accelerated tachyarrhythmias were appropriate ATP in 139 (88.5%) and inappropriate ATP in 14 (8.9%), as well as appropriate and inappropriate shocks in 2 (1.3%) episodes, respectively. Chronic heart failure was significantly correlated with the occurrence and recurrence of acceleration (p<0.001). Patients with accelerated ventricular tachyarrhythmia and subsequent shock therapy revealed higher all-cause mortality (HR 1.760; 95% CI 1.286-2.410; p<0.001) as well as higher cardiac mortality (HR 2.555; 95% CI 1.446-4.513; p=0.001). The correlation between acceleration and all-cause mortality was independent of left ventricular function (HR 2.076; 95% CI 1.633-2.639; p<0.001).
  
  
  CONCLUSIONS
  Ventricular ATP with arrhythmia acceleration and subsequent shock delivery is a frequent and serious complication of ICD therapy that predominantly occurs in patients with reduced left ventricular function. Finally, occurrence of accelerated ventricular tachyarrhythmias was associated with increased all-cause mortality.
authors.affiliation: Department of Internal Medicine II, Division of Cardiology, Medical University of Vienna, Vienna, Austria. christoph.schukro@meduniwien.ac.at
authors.forename: Christoph
authors.initials: C
authors.lastname: Schukro
authors.forename: Lukas
authors.initials: L
authors.lastname: Leitner
authors.forename: Johannes
authors.initials: J
authors.lastname: Siebermair
authors.forename: Thomas
authors.initials: T
authors.lastname: Pezawas
authors.forename: Günter
authors.initials: G
authors.lastname: Stix
authors.forename: Johannes
authors.initials: J
authors.lastname: Kastner
authors.forename: Herwig
authors.initials: H
authors.lastname: Schmidinger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D017147:Defibrillators, Implantable / Q000639:trends; D004554:Electric Countershock / Q000401:mortality* / Q000639:trends; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy*; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy*; D055815:Young Adult