title: Reduced risk of life-threatening ventricular tachyarrhythmias with cardiac resynchronization therapy: relationship to left ventricular ejection fraction.
abstract: OBJECTIVE
  We hypothesized that the relationship between LVEF and the risk of life-threatening ventricular tachyarrhythmias (VTAs) may modify the effect of a CRT device with a defibrillator (CRT-D) on VTA risk.
  
  
  RESULTS
  The risk of fast (≥200 b.p.m.) ventricular tachycardia/ventricular fibrillation (VT/VF) and the benefit of CRT-D in reducing VT/VF were assessed by baseline LVEF (categorized as ≤30% or 30% and assessed as a continuous measurement) in 1783 patients with mild heart failure (HF) implanted with an implantable cardioverter defibrillator (ICD) or CRT-D, enrolled in MADIT-CRT. Higher LVEF (>30%) at baseline was associated with a significantly lower risk of fast VT/VF [hazard ratio (HR) 0.54, P = 0.006], VT/VF (HR 0.62, P = 0.005), and VT/VF/death (HR 0.64, P = 0.003). Treatment with CRT-D was shown to reduce the risk of fast VT/VF in patients with LVEF ≤ 30% (n = 1100) [HR 0.64, 95% confidence interval (CI) 0.48-0.85, P = 0.002], but not among those with LVEF > 30% (n = 683) (HR 1.19, 95% CI 0.73-1.91, P = 0.502, interaction P-value = 0.03). When LVEF was assessed as a continuous measure, each 5% increment was shown to be associated with a significant 30% (P < 0.001) reduction in the risk for fast VT/VF, and with a corresponding linear reduction in the benefit of CRT-D in reducing fast VTA risk (P -value for treatment by LVEF interaction = 0.003).
  
  
  CONCLUSIONS
  Our data suggest that in mild HF patients with cardiomyopathy there is an inverse correlation between LVEF and the risk of life-threatening VTAs, possibly contributing to the attenuation in the antiarrhythmic properties of CRT with increasing left ventricular function.
  
  
  BACKGROUND
  NCT00180271.
authors.affiliation: University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Valentina
authors.initials: V
authors.lastname: Kutyifa
authors.affiliation: University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Moss
authors.affiliation: Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Solomon
authors.affiliation: University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.affiliation: University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Mehmet K
authors.initials: MK
authors.lastname: Aktas
authors.affiliation: University of Rochester Medical Center, Rochester, NY, USA.|Cardiology Department, Rabin Medical Center, Petah Tiqva, and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Alon
authors.initials: A
authors.lastname: Barsheshet
authors.affiliation: Semmelweis University, Heart Center, Budapest, Hungary.
authors.forename: Bela
authors.initials: B
authors.lastname: Merkely
authors.affiliation: University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.affiliation: University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Ilan
authors.initials: I
authors.lastname: Goldenberg
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D017147:Defibrillators, Implantable; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013318:Stroke Volume / Q000502:physiology*; D017180:Tachycardia, Ventricular / Q000628:therapy; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: Cardiac resynchronization therapy; Heart failure; Implantable cardioverter defibrillator; Left ventricular ejection fraction; Ventricular tachyarrhythmias