title: Clinical significance of ventricular tachyarrhythmias in patients treated with CRT-D.
abstract: BACKGROUND
  Data on the outcome of cardiac resynchronization therapy with defibrillator (CRT-D) in patients developing ventricular arrhythmias are limited.
  
  
  OBJECTIVE
  To evaluate the prognostic value of ventricular tachycardia (VT) or ventricular fibrillation (VF) episodes by heart rate in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy trial.
  
  
  METHODS
  Slow VT was defined as VTs with heart rate < 200 beats/min. Fast VT with a heart rate ≥200 beats/min and VF (>250 beats/min) were considered as a combined category. Primary end point was heart failure (HF) or death. Secondary end point included all-cause mortality.
  
  
  RESULTS
  There were 228 (12.7%) patients with slow VT and 198 (11.1%) with fast VT/VF. In time-dependent analysis, slow VT was associated with an increased risk of HF/death in CRT-D patients with left branch bundle block (LBBB; hazard ratio [HR] 3.19; 95% confidence interval [CI] 1.83-5.55; P < .001), but not in patients with implantable cardioverter-defibrillator (ICD) (HR 1.03; 95% CI 0.52-2.19; P = .867; interaction P value = .017). CRT-D patients with LBBB and fast VT/VF doubled their risk of HF/death compared to ICD patients (interaction P value = .06). Slow VT events were also predictive of death in CRT-D patients with LBBB (HR 3.48; 95% CI 1.66-7.28; P < .001), but not in ICD patients (interaction P value = .06). Slow VTs were highly predictive of subsequent fast VT/VF (HR 4.33; 95% CI 3.01-6.24; P < .001).
  
  
  CONCLUSIONS
  Slow VT episodes are predictive of subsequent fast VT/VF. Slow VT and fast VT/VF episodes in CRT-D patients are associated with an increased risk of subsequent HF/death. CRT-D-treated LBBB patients with slow VTs have a significantly higher risk of mortality.
authors: University of Rochester Medical Center, Rochester, New York 14642, USA. Valentina.Kutyifa@heart. roehester.edu
authors: Valentina
authors: V
authors: Kutyifa
authors: Helmut U
authors: HU
authors: Klein
authors: Paul J
authors: PJ
authors: Wang
authors: Scott
authors: S
authors: McNitt
authors: Bronislava
authors: B
authors: Polonsky
authors: Endre
authors: E
authors: Zima
authors: Bela
authors: B
authors: Merkely
authors: Arthur J
authors: AJ
authors: Moss
authors: Wojciech
authors: W
authors: Zareba
mesh_terms: D000368:Aged; D002170:Canada / Q000453:epidemiology; D017147:Defibrillators, Implantable; D018450:Disease Progression; D004562:Electrocardiography; D005060:Europe / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D006339:Heart Rate; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015996:Survival Rate / Q000639:trends; D017180:Tachycardia, Ventricular / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology