title: A new method to investigate the response to the morphology discrimination algorithm in patients with ICD.
abstract: BACKGROUND
  Inappropriate therapy for supraventricular tachyarrhythmia is still a major problem in implantable cardioverter defibrillators (ICD). The morphology discrimination algorithm compares the morphology of a tachycardia electrogram with a stored template on a beat-to-beat basis. However, algorithm responders could not yet be identified prior to the occurrence of first tachycardia episodes. We analyzed whether rapid atrial pacing and/or exercise testing can be used for identification of responders and compared the results with ICD detected tachycardia.
  
  
  METHODS
  22 patients (16 male, 61+/-14 years) with dual-chamber ICDs have been enrolled. Patients underwent a standardized bicycle exercise testing and an atrial pacing protocol. For both tests, morphology match scores of 8 consecutive beats were analyzed for each 10-bpm-step increment above sinus rhythm. Patients were categorized as responders, if morphology match was > or = 90% of tested heart rates. During follow-up, ICD stored episodes with morphology discrimination activated were evaluated.
  
  
  RESULTS
  There were no significant differences between morphology match (85+/-29% vs. 84+/-27%) and linear regression slope B (-0.19+/-0.87 vs. -0.20+/-0.48) during exercise testing and atrial pacing. 16 patients (73%) were classified as responders. During follow-up (739+/-338 days) 121 sustained supraventricular (n=88) and ventricular tachycardia (n=33) were detected in 10 patients (45%). Specificity for tachycardia discrimination was 78% overall, 100% in responders and 22% in non-responders.
  
  
  CONCLUSIONS
  Exercise testing and atrial pacing were equally suitable for identification of patients who seem to respond to the morphology discrimination algorithm with a high specificity for ventricular tachycardia discrimination. Thus, morphology match tests are suggested to optimize tachycardia discrimination and to reduce inadequate therapies.
authors.affiliation: Department of Cardiology, Klinikum Coburg, Germany. amsinha@gmx.de
authors.forename: Anil-Martin
authors.initials: AM
authors.lastname: Sinha
authors.forename: Rainer
authors.initials: R
authors.lastname: Schimpf
authors.forename: Jörg Otto
authors.initials: JO
authors.lastname: Schwab
authors.forename: Frank
authors.initials: F
authors.lastname: Birkenhauer
authors.forename: Ole A
authors.initials: OA
authors.lastname: Breithardt
authors.forename: Johannes
authors.initials: J
authors.lastname: Brachmann
authors.forename: Volker
authors.initials: V
authors.lastname: Schibgilla
authors.forename: Peter
authors.initials: P
authors.lastname: Hanrath
authors.forename: Christoph
authors.initials: C
authors.lastname: Stellbrink
mesh_terms: D000465:Algorithms; D016009:Chi-Square Distribution; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000503:physiopathology; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013617:Tachycardia, Supraventricular / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome