title: Effect of defibrillation threshold testing on heart failure hospitalization or death in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT).
abstract: BACKGROUND
  Defibrillation threshold (DFT) testing is commonly practiced at the time of implantable cardioverter-defibrillator (ICD) implant. The clinical consequence of ICD shocks delivered during DFT testing is unknown.
  
  
  OBJECTIVE
  The purpose of this study was to determine the impact of ICD shocks and ICD shock energy level delivered during DFT testing in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT) on clinical outcomes.
  
  
  METHODS
  Patients who underwent DFT testing within 1 month of device implant were categorized by the number of ICD shocks delivered during DFT testing (0, 1, 2, ≥3 shocks) and according to high vs low (>20 J vs ≤20 J) energy ICD shocks. Clinical outcomes consisting of heart failure (HF) or death, death alone, HF alone, and ventricular tachycardia or ventricular fibrillation were analyzed in each group.
  
  
  RESULTS
  DFT testing was performed in 1,659 patients within 1 month of device implant (1 shock in 365 patients, 2 shocks in 896 patients, 3+ shocks in 398 patients). High-energy ICD shocks were delivered in 609 patients. Increasing number of ICD shocks during DFT testing was not associated with an increase risk for the primary end-point of HF or death or for any of the secondary end-points of HF alone, VT/VF alone, or death. Delivery of high vs low-energy ICD shocks was not associated with adverse clinical outcomes.
  
  
  CONCLUSIONS
  In patients with mild symptoms of HF, increasing number of ICD shocks and delivery of high energy ICD shocks during DFT testing was not associated with increased risk for HF or death or future VT/VF episodes.
authors.affiliation: University of Rochester Medical Center, Rochester, New York 14642, USA. Mehmet_Aktas@urmc.rochester.edu
authors.forename: Mehmet K
authors.initials: MK
authors.lastname: Aktas
authors.forename: David T
authors.initials: DT
authors.lastname: Huang
authors.forename: James P
authors.initials: JP
authors.lastname: Daubert
authors.forename: Claudio D
authors.initials: CD
authors.lastname: Schuger
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.forename: Ilan
authors.initials: I
authors.lastname: Goldenberg
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Moss
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000379:methods* / Q000401:mortality*; D017147:Defibrillators, Implantable; D004554:Electric Countershock; D004562:Electrocardiography; D004868:Equipment Failure; D004869:Equipment Safety; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy*; D017052:Hospital Mortality / Q000639:trends; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D015996:Survival Rate; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000401:mortality / Q000628:therapy; D013997:Time Factors; D016896:Treatment Outcome