title: Clinical experience with a new detection algorithm for differentiation of supraventricular from ventricular tachycardia in a dual-chamber defibrillator.
abstract: BACKGROUND
  Inadequate therapy for supraventricular tachyarrhythmias (SVT) is a frequent problem of implantable cardioverter defibrillators (ICD). Dual-chamber ICDs have been developed to improve discrimination of SVT from ventricular tachycardia (VT). We investigated the positive predictivity, sensitivity, and specificity of a new algorithm, the SMART detection trade mark algorithm, incorporated in the Phylax AV (Biotronik) dual-chamber ICD.
  
  
  RESULTS
  Two hundred nine patients (185 men, age 64 +/- 11 years) received a Phylax AV ICD with SMART detection trade mark activated. In 138 of these patients, 1,245 sustained tachycardia episodes with a detailed electrogram were stored in the device during a follow-up period of 10 +/- 6 months. Episodes were correctly classified as ventricular fibrillation (VF, n = 178) in 52 patients, VT (n = 641) in 98 patients, and SVT (n = 385) in 48 patients by the algorithm. Forty-one true SVT episodes (3.3%) were misclassified as VT: atrial fibrillation (n = 7) and flutter (n = 1), sinus tachycardia (n = 12), and other SVT (n = 21). The positive predictivity for VF/VT was 94.5% (95% CI 92.7-95.8) uncorrected and 94.5% (95% CI 92.9-95.8%) corrected with the generalized equation estimation (GEE) method. The positive predictivity for SVT was 100%. The specificity was 88.9% (95% CI 85.6-91.6%) uncorrected and 89.0% (95% CI 85.6-91.6%) corrected with the GEE method with a sensitivity of 100%.
  
  
  CONCLUSIONS
  The SMART detection trade mark algorithm was safe and reliable for the detection of all ventricular tachycardias. Although its specificity was high, it should be improved with regard to SVT to avoid inappropriate ICD therapies.
authors.affiliation: Universitätsklinikum Aachen, Germany.
authors.forename: Anil-Martin
authors.initials: AM
authors.lastname: Sinha
authors.forename: Christoph
authors.initials: C
authors.lastname: Stellbrink
authors.forename: Andreas
authors.initials: A
authors.lastname: Schuchert
authors.forename: Bernhard
authors.initials: B
authors.lastname: Mox
authors.forename: Luc
authors.initials: L
authors.lastname: Jordaens
authors.forename: Dominique
authors.initials: D
authors.lastname: Lamaison
authors.forename: Jaswinder
authors.initials: J
authors.lastname: Gill
authors.forename: Andrew
authors.initials: A
authors.lastname: Kaplan
authors.forename: Bela
authors.initials: B
authors.lastname: Merkely
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000145:classification / Q000175:diagnosis / Q000628:therapy; D017147:Defibrillators, Implantable; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005060:Europe / Q000453:epidemiology; D005189:False Positive Reactions; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013617:Tachycardia, Supraventricular / Q000175:diagnosis* / Q000628:therapy*; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000628:therapy*; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology