title: Long-term benefit of primary prevention with an implantable cardioverter-defibrillator: an extended 8-year follow-up study of the Multicenter Automatic Defibrillator Implantation Trial II.
abstract: BACKGROUND
  The Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) showed a significant 31 reduction in the risk of death with primary implantable cardioverter-defibrillator (ICD) therapy during a median follow-up of 1.5 years. However, currently there are no data on the long-term efficacy of primary defibrillator therapy.
  
  
  RESULTS
  MADIT-II enrolled 1232 patients with ischemic left ventricular dysfunction who were randomized to ICD and non-ICD medical therapy and were followed up through November 2001. For the present long-term study, we acquired posttrial mortality data through March 2009 for all study participants (median follow-up, 7.6 years). Multivariate Cox proportional hazards regression modeling was performed to calculate the hazard ratio for ICD versus non-ICD therapy during long-term follow-up. At 8 years of follow-up, the cumulative probability of all-cause mortality was 49 among patients treated with an ICD compared with 62 among non-ICD patients (P<0.001). Multivariate analysis demonstrated that ICD therapy was associated with a significant long-term survival benefit (hazard ratio for 0- through 8-year mortality=0.66 [95 confidence interval, 0.56 to 0.78]; P<0.001). Treatment with an ICD was shown to be associated with a significant reduction in the risk of death during the early phase of the extended follow-up period (0 through 4 years: hazard ratio=0.61 [95 confidence interval, 0.50 to 0.76]; P<0.001) and with continued life-saving benefit during the late phase of follow-up (5 through 8 years: hazard ratio=0.74 [95 confidence interval, 0.57 to 0.96]; P=0.02).
  
  
  CONCLUSIONS
  Our findings demonstrate a sustained 8-year survival benefit with primary ICD therapy in the MADIT-II population.
authors.affiliation: Heart Research Follow-up Program, Box 653, University of Rochester Medical Center, Rochester, NY 14642, USA. Ilan.Goldenberg@heart.rochester.edu
authors.forename: Ilan
authors.initials: I
authors.lastname: Goldenberg
authors.forename: John
authors.initials: J
authors.lastname: Gillespie
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Moss
authors.forename: W Jackson
authors.initials: WJ
authors.lastname: Hall
authors.forename: Helmut
authors.initials: H
authors.lastname: Klein
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.forename: Mary W
authors.initials: MW
authors.lastname: Brown
authors.forename: Iwona
authors.initials: I
authors.lastname: Cygankiewicz
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
mesh_terms: D000368:Aged; D017147:Defibrillators, Implantable; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality / Q000517:prevention & control* / Q000628:therapy*; D016016:Proportional Hazards Models; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome