title: Performance of a new single-chamber ICD algorithm: discrimination of supraventricular and ventricular tachycardia based on vector timing and correlation.
abstract: OBJECTIVE
  Interval- and morphology-based algorithms have been used in modern implantable cardioverter defibrillators (ICDs) to discriminate supraventricular tachycardia (SVT) from other rhythms. A newly developed ICD discrimination algorithm, Rhythm ID (Guidant Corporation, St Paul, MN, USA), uses both interval-based metrics and an electrogram vector timing and correlation (VTC) algorithm in a dual-chamber ICD. In a single-chamber ICD, Rhythm ID contains only the VTC component. This study conducted a retrospective analysis of the performance of Rhythm ID for the detection of induced and spontaneous rhythms in a single-chamber ICD.
  
  
  RESULTS
  This study gathered the data from a prospective, multicentre clinical trial. Ninety-six patients were implanted with a dual-chamber ICD. For this study, each episode was analysed to determine the performance of the single-chamber ICD Rhythm ID algorithm. The mean age of the patients implanted with the device was 67+/-11 years. Seventy-eight patients were male. The primary cardiovascular disease was coronary artery disease and the primary tachyarrhythmia was monomorphic ventricular tachycardia (VT). The mean follow-up time was 11.4 months. A total of 369 induced and spontaneous ventricular arrhythmias was analysed. The algorithm detected 100% of ventricular arrhythmias. Four hundred and forty-two SVT episodes were analysed, including 145 induced and 297 spontaneous. The SVTs were atrial fibrillation (n=199), atrial flutter (n=135), and 1:1 SVT (n=108). The single-chamber ICD Rhythm ID algorithm successfully discriminated 403 SVT episodes and achieved a specificity of 91%.
  
  
  CONCLUSIONS
  The single-chamber version of Rhythm ID demonstrated high specificity without compromising sensitivity.
authors.affiliation: Deborah Heart and Lung Center, 200 Trenton Road, Browns Mills, NJ 08018, USA. corbisieror@deborah.org
authors.forename: Raffaele
authors.initials: R
authors.lastname: Corbisiero
authors.forename: Michael A
authors.initials: MA
authors.lastname: Lee
authors.forename: David R
authors.initials: DR
authors.lastname: Nabert
authors.forename: James A
authors.initials: JA
authors.lastname: Coman
authors.forename: David J
authors.initials: DJ
authors.lastname: Breiter
authors.forename: Mark
authors.initials: M
authors.lastname: Schwartz
authors.forename: Edward
authors.initials: E
authors.lastname: McKittrick
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000368:Aged; D000465:Algorithms; D003324:Coronary Artery Disease / Q000503:physiopathology / Q000628:therapy; D017147:Defibrillators, Implantable; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013617:Tachycardia, Supraventricular / Q000503:physiopathology / Q000628:therapy*; D017180:Tachycardia, Ventricular / Q000503:physiopathology / Q000628:therapy*