title: Association of Implantable Cardioverter Defibrillator Therapy with All-Cause Mortality-A Systematic Review and Meta-Analysis.
abstract: BACKGROUND
  Implantable cardioverter defibrillators (ICDs) have become the standard approach for prevention of sudden cardiac death. Whether ICD therapy is an independent predictor of all-cause mortality is controversial. We made the systematic review and meta-analysis to estimate the impact of ICD therapy on mortality.
  
  
  METHODS
  We searched the PubMed and Embase databases for studies evaluating the effect of ICD shocks or antitachycardia pacing (ATP) on mortality. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated using random effects models.
  
  
  RESULTS
  Thirteen cohort studies were identified. Mean ejection fraction of the population was 23-35%; 68.0% had ischemic etiology, and 74.5% received a primary prevention ICD implantation. Appropriate shocks were an independent predictor of increased mortality compared with no-shock or no-therapy patients (HR 2.07, 2.76, respectively). In contrast, inconsistent results were obtained during inappropriate-shock analyses: when compared with no-shock patients, inappropriate shocks were associated with an increased risk of death (HR 1.54, 95% CI: 1.25-1.89, P < 0.0001); however, when compared to no-therapy patients, there was no relationship between inappropriate shocks and mortality (HR 1.20, 95% CI: 0.90-1.61, P = 0.22). Subgroup analysis in heart failure patients also did not find any difference in mortality between inappropriate-shock and no-therapy patients. No increased risk of mortality was found in the patients who experienced appropriate or inappropriate ATP only.
  
  
  CONCLUSIONS
  Appropriate shocks were associated with an increased mortality in ICD patients. However, whether inappropriate shocks worsened the clinical outcome was controversial, and larger prospective trials are needed to clarify the issue.
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China.|Department of Cardiology, Taixing People's Hospital, Taixing, Jiangsu Province, China.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Qian
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China.
authors.forename: Jianghong
authors.initials: J
authors.lastname: Guo
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Hou
authors.affiliation: Department of Cardiology, Taixing People's Hospital, Taixing, Jiangsu Province, China.
authors.forename: Guangzhi
authors.initials: G
authors.lastname: Feng
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China.
authors.forename: Jiangang
authors.initials: J
authors.lastname: Zou
mesh_terms: D017677:Age Distribution; D000368:Aged; D016757:Death, Sudden, Cardiac / Q000453:epidemiology* / Q000517:prevention & control*; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D005260:Female; D006333:Heart Failure / Q000401:mortality* / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D017678:Sex Distribution; D015996:Survival Rate
keywords: antitachycardia pacing; appropriate shocks; implantable cardioverter defibrillator; inappropriate shocks; mortality