title: Impact of shocks on mortality in patients with ischemic or dilated cardiomyopathy and defibrillators implanted for primary prevention.
abstract: BACKGROUND
  Emerging interest is seen in the paradox of defibrillator shocks for ventricular tachyarrhythmia and increased mortality risk. Particularly in patients with dilated cardiomyopathy (DCM), the prognostic importance of shocks is unclear. The purpose of this study was to compare the outcome after shocks in patients with ischemic cardiomyopathy (ICM) or DCM and defibrillators (ICD) implanted for primary prevention.
  
  
  RESULTS
  Data of 561 patients were analyzed (mean age 68.6±10.6 years, mean left ventricular ejection fraction 28.6±7.3%). During a median follow-up of 49.3 months, occurrence of device therapies and all-cause mortality were recorded. 74 out of 561 patients (13.2%) experienced ≥1 appropriate and 51 out of 561 patients (9.1%) ≥1 inappropriate shock. All-cause mortality was 24.2% (136 out of 561 subjects). Appropriate shock was associated with a trend to higher mortality in the overall patient population (HR 1.48, 95% CI 0.96-2.28, log rank p = 0.072). The effect was significant in ICM patients (HR 1.61, 95% CI 1.00-2.59, log rank p = 0.049) but not in DCM patients (HR 1.03, 95% CI 0.36-2.96, log rank p = 0.96). Appropriate shocks occurring before the median follow-up revealed a much stronger impact on mortality (HR for the overall patient population 2.12, 95% CI 1.24-3.63, p = 0.005). The effect was driven by ICM patients (HR 2.48, 95% CI 1.41-4.37, p = 0.001), as appropriate shocks again did not influence survival of DCM patients (HR 0.63, 95% CI 0.083-4.75, p = 0.65). Appropriate shocks occurring after the median follow-up and inappropriate shocks occurring at any time revealed no impact on survival in any of the groups (p = ns).
  
  
  CONCLUSIONS
  Appropriate shocks are associated with reduced survival in patients with ICM but not in patients with DCM and ICDs implanted for primary prevention. Furthermore, the negative effect of appropriate shocks on survival in ICM patients is only evident within the first 4 years after device implantation.
authors.affiliation: 1st Department of Medicine-Cardiology, University Medical Centre Mannheim, Mannheim, Germany. florian.streitner@umm.de
authors.forename: Florian
authors.initials: F
authors.lastname: Streitner
authors.forename: Thomas
authors.initials: T
authors.lastname: Herrmann
authors.forename: Juergen
authors.initials: J
authors.lastname: Kuschyk
authors.forename: Siegfried
authors.initials: S
authors.lastname: Lang
authors.forename: Christina
authors.initials: C
authors.lastname: Doesch
authors.forename: Theano
authors.initials: T
authors.lastname: Papavassiliu
authors.forename: Ines
authors.initials: I
authors.lastname: Streitner
authors.forename: Christian
authors.initials: C
authors.lastname: Veltmann
authors.forename: Dariusch
authors.initials: D
authors.lastname: Haghi
authors.forename: Martin
authors.initials: M
authors.lastname: Borggrefe
mesh_terms: D000367:Age Factors; D000368:Aged; D002311:Cardiomyopathy, Dilated / Q000150:complications*; D002423:Cause of Death; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control; D047548:Defibrillators; D017147:Defibrillators, Implantable; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications*; D011379:Prognosis; D012737:Sex Factors; D016019:Survival Analysis; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000209:etiology* / Q000401:mortality / Q000517:prevention & control / Q000628:therapy*