title: Mortality reduction by implantable cardioverter-defibrillators in high-risk patients with heart failure, ischemic heart disease, and new-onset ventricular arrhythmia: an effectiveness study.
abstract: OBJECTIVE
  To investigate the generalizability of the reduction in mortality posed by implantable cardioverter-defibrillators, we examined the effectiveness of defibrillators as applied in routine medical practice.
  
  
  BACKGROUND
  Implantable cardioverter-defibrillators have been shown to be efficacious in the primary and secondary prevention of overall and cardiovascular mortality in clinical trials.
  
  
  METHODS
  Using the National Veterans Administration database, we identified a cohort of 6,996 patients from 1995 to 1999 with new-onset ventricular arrhythmia and pre-existing ischemic heart disease and congestive heart failure, of which 1,442 received a defibrillator, and followed them for three years to determine rates of mortality. With multivariate logistic regression analyses that adjusted for demographics, illness severity, and comorbidity, we assessed overall, cardiovascular, and noncardiovascular rates of mortality. To further address potential confounding, we also stratified the cohort by quintiles using a multivariable propensity score for each patient and determined mortality rates.
  
  
  RESULTS
  For the overall cohort, multivariate regression showed that those who received defibrillators had significantly lower all-cause (odds ratio [OR] 0.52; 95% confidence interval [CI] 0.45 to 0.60) and cardiovascular (OR 0.56; 95% CI 0.49 to 0.65)] rates of mortality at three years. No significant differences were noted between groups in their rates of noncardiovascular mortality (OR 0.92; 95% CI 0.77 to 1.10). Propensity score analysis demonstrated similar mortality reduction benefits at three years: risk ratio (RR) 0.72 (95% CI 0.69 to 0.79) for all-cause; RR 0.70 (95% CI 0.63 to 0.78) for cardiovascular; and RR 0.95 (95% CI 0.83 to 1.08) for noncardiovascular rates of mortality. These results suggest that one death is prevented in this patient population for every four to five patients receiving a defibrillator for three years.
  
  
  CONCLUSIONS
  Implantable cardioverter-defibrillators in routine medical practice significantly reduce cardiovascular and all-cause rates of mortality at levels similar to secondary prevention trials.
authors.affiliation: Division of Cardiology, University of Michigan School of Medicine, USA. paulchan@umich.edu
authors.forename: Paul S
authors.initials: PS
authors.lastname: Chan
authors.forename: Rodney A
authors.initials: RA
authors.lastname: Hayward
mesh_terms: D000368:Aged; D015331:Cohort Studies; D015897:Comorbidity; D017147:Defibrillators, Implantable; D003953:Diagnosis-Related Groups / Q000706:statistics & numerical data; D005260:Female; D006333:Heart Failure; D006801:Humans; D008297:Male; D017202:Myocardial Ischemia; D012044:Regression Analysis; D012720:Severity of Illness Index; D016019:Survival Analysis; D017180:Tachycardia, Ventricular / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D014481:United States / Q000453:epidemiology; D014728:Veterans / Q000706:statistics & numerical data