title: Failed anti-tachycardia pacing can be used to differentiate atrial arrhythmias from ventricular tachycardia in implantable cardioverter-defibrillators.
abstract: BACKGROUND
  Atrial fibrillation/tachycardia (AF/AT) may result in inappropriate therapies in implantable cardioverter-defibrillators (ICDs). The post-pacing interval (PPI) and tachycardia cycle length difference (PPI - TCL) has been previously demonstrated to indicate the proximity of the pacing site to a tachycardia origin.
  
  
  OBJECTIVE
  We postulated that the PPI and PPI - TCL would be greater in AT/AF vs. ventricular tachycardia (VT) after episodes of failed anti-tachycardia pacing (ATP).
  
  
  RESULTS
  This was a single-centre, retrospective study evaluating consecutive patients implanted with dual (DR)/biventricular (BIV) ICDs. Stored electrograms were used to determine whether the ATP captured the arrhythmia and the arrhythmia did not present with primary or secondary termination. Measurements were done using manual calipers. A total of 155 patients were included. There were 79 BIV and 76 DR devices. In total, 39 episodes were identified in 20 patients over a 23-month follow-up period. A total of 76 sequences of ATP (burst/ramp) were delivered, 28 (37%) of them inappropriate. Fifty-one events (18 AT/AF and 33 VT) were compared. The mean PPI was 693 ± 96 vs. 512 ± 88 ms (P < 0.01) and the mean PPI - TCL was 330 ± 97 vs. 179 ± 103 ms (P < 0.01) for AT/AF and VT, respectively. Cut-offs of 615 ms for the PPI [area under curve (AUC) 0.93; 95% confidence interval (CI): 0.84-1.00; P < 0.01] and 260 ms for PPI - TCL (AUC 0.86; 95% CI: 0.74-0.98; P < 0.01) were identified.
  
  
  CONCLUSIONS
  The PPI and PPI - TCL after failed ATP differs significantly between AF/AT and VT and are therefore useful indices to discriminate between supraventricular tachycardia and VT in ICDs.
authors.affiliation: Heart Rhythm Service, Queen's University and Kingston General Hospital, Kingston, ON K7L 2V7, Canada.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Michael
authors.affiliation: Heart Rhythm Service, Queen's University and Kingston General Hospital, Kingston, ON K7L 2V7, Canada.
authors.forename: Andres
authors.initials: A
authors.lastname: Enriquez
authors.affiliation: Heart Rhythm Service, Queen's University and Kingston General Hospital, Kingston, ON K7L 2V7, Canada barancha@kgh.kari.net.
authors.forename: Adrian
authors.initials: A
authors.lastname: Baranchuk
authors.affiliation: Heart Rhythm Service, Queen's University and Kingston General Hospital, Kingston, ON K7L 2V7, Canada.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Haley
authors.affiliation: Heart Rhythm Service, Queen's University and Kingston General Hospital, Kingston, ON K7L 2V7, Canada.
authors.forename: Jane
authors.initials: J
authors.lastname: Caldwell
authors.affiliation: Heart Rhythm Service, Queen's University and Kingston General Hospital, Kingston, ON K7L 2V7, Canada.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Simpson
authors.affiliation: Heart Rhythm Service, Queen's University and Kingston General Hospital, Kingston, ON K7L 2V7, Canada.
authors.forename: Hoshiar
authors.initials: H
authors.lastname: Abdollah
authors.affiliation: Heart Rhythm Service, Queen's University and Kingston General Hospital, Kingston, ON K7L 2V7, Canada.
authors.forename: Damian P
authors.initials: DP
authors.lastname: Redfearn
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation; D017147:Defibrillators, Implantable; D003937:Diagnosis, Differential; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013612:Tachycardia, Ectopic Atrial / Q000175:diagnosis* / Q000628:therapy*; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000628:therapy*
keywords: Anti-tachycardia pacing; ICD; Inappropriate therapies; SVT–VT discrimination; Ventricular tachycardia