title: Risk stratification for primary implantation of a cardioverter-defibrillator in patients with ischemic left ventricular dysfunction.
abstract: OBJECTIVE
  The study was designed to develop a simple risk stratification score for primary therapy with an implantable cardioverter-defibrillator (ICD).
  
  
  BACKGROUND
  Current guidelines recommend primary ICD therapy in patients with a low ejection fraction (EF). However, the benefit of the ICD in the low EF population may not be uniform.
  
  
  METHODS
  Best-subset proportional-hazards regression analysis was used to develop a simple clinical risk score for the end point of all-cause mortality in patients allocated to the conventional therapy arm of MADIT (Multicenter Automatic Defibrillator Implantation Trial)-II after excluding a pre-specified subgroup of very high-risk (VHR) patients (defined by blood urea nitrogen [BUN] >or=50 mg/dl and/or serum creatinine >or=2.5 mg/dl). The benefit of the ICD was then assessed within risk score categories and separately in VHR patients.
  
  
  RESULTS
  The selected risk score model comprised 5 clinical factors (New York Heart Association functional class >II, age >70 years, BUN >26 mg/dl, QRS duration >0.12 s, and atrial fibrillation). Crude mortality rates in the conventional group were 8% and 28% in patients with 0 and >or=1 risk factors, respectively, and 43% in VHR patients. Defibrillator therapy was associated with a 49% reduction in the risk of death (p < 0.001) among patients with >or=1 risk factors (n = 786), whereas no ICD benefit was identified in patients with 0 risk factors (n = 345; hazard ratio 0.96; p = 0.91) and in VHR patients (n = 60; hazard ratio 1.00; p > 0.99).
  
  
  CONCLUSIONS
  Our data suggest a U-shaped pattern for ICD efficacy in the low-EF population, with pronounced benefit in intermediate-risk patients and attenuated efficacy in lower- and higher-risk subsets.
authors.affiliation: Department of Medicine, University of Rochester Medical Center, Rochester, New York 14642, USA. Ilan.Goldenberg@heart.rochester.edu
authors.forename: Ilan
authors.initials: I
authors.lastname: Goldenberg
authors.forename: Anant K
authors.initials: AK
authors.lastname: Vyas
authors.forename: W Jackson
authors.initials: WJ
authors.lastname: Hall
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Moss
authors.forename: Hongyue
authors.initials: H
authors.lastname: Wang
authors.forename: Hua
authors.initials: H
authors.lastname: He
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.forename: Mark L
authors.initials: ML
authors.lastname: Andrews
mesh_terms: D000368:Aged; D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000517:prevention & control; D017147:Defibrillators, Implantable; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000628:therapy*; D017063:Outcome Assessment, Health Care; D016016:Proportional Hazards Models; D018570:Risk Assessment / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000209:etiology / Q000401:mortality / Q000628:therapy*