title: Clinical and electrophysiologic predictors of ventricular tachyarrhythmia recurrence in patients with implantable cardioverter defibrillators.
abstract: BACKGROUND
  Not all patients experience recurrent sustained ventricular tachyarrhythmias after placement of an implantable cardioverter defibrillator (ICD). We evaluated the clinical and electrophysiologic predictors of ventricular tachycardia (VT) and ventricular fibrillation (VF) recurrence following ICD implantation.
  
  
  RESULTS
  Consecutive patients (n = 133) underwent 4 +/- 3 serial electrophysiologic studies (EPS) over 50 +/- 26 months following ICD implantation. Sustained VT/VF could always be induced during follow-up EPS in 49 patients; sustained VT/VF was sometimes induced during follow-up EPS in 47 patients; and sustained VT/VF could never be induced during follow-up EPS in 37 patients. Spontaneous VT/VF requiring ICD therapy occurred in 107 patients during follow-up. Patients with sustained VT/VF that was always inducible or sometimes inducible during follow-up experienced more frequent episodes of VT/VF following ICD implant (20.5, 95% CI 12.7-33.0; and 17.8, 95% CI 11.3-28.1 episodes/patient respectively; vs 3.0, 95% CI 2.0-4.6 episodes/patient for patients with VT/VF never induced, P < 0.001). Inducibility of sustained VT/VF post-ICD implant (P < 0.001) and sustained VT as the presenting arrhythmia (P = 0.02) were independent predictors of spontaneous VT/VF recurrence.
  
  
  CONCLUSIONS
  Reproducibly inducible VT/VF following ICD implantation predicts a high probability of VT/VF recurrence and identifies a cohort of patients who experience frequent episodes of VT/VF over time. Persistent noninducibility of sustained VT/VF identifies a group of patients who experience no or very few episodes of VT/VF recurrence.
authors.affiliation: Division of Cardiology, Foothills Hospital and Cardiovascular Research Group, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada. amgillis@ucalgary.ca
authors.forename: Anne M
authors.initials: AM
authors.lastname: Gillis
authors.forename: Robert S
authors.initials: RS
authors.lastname: Sheldon
authors.forename: D George
authors.initials: DG
authors.lastname: Wyse
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Duff
authors.forename: Margaret R
authors.initials: MR
authors.lastname: Cassidy
authors.forename: L Brent
authors.initials: LB
authors.lastname: Mitchell
mesh_terms: D000368:Aged; D015331:Cohort Studies; D017147:Defibrillators, Implantable; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012008:Recurrence; D012680:Sensitivity and Specificity; D013318:Stroke Volume / Q000502:physiology; D017180:Tachycardia, Ventricular / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000209:etiology / Q000503:physiopathology / Q000628:therapy