title: Impact of QRS duration on survival benefit with prophylactic implantable cardioverter-defibrillators: a meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  QRS duration is an important risk factor for both sudden cardiac death and all-cause mortality in patients with moderate to severe left ventricular systolic dysfunction. However, it is unknown whether baseline QRS duration can help predict the mortality benefit from implantable cardioverter-defibrillators (ICDs) when used for primary prevention purposes.
  
  
  OBJECTIVE
  Our objective was to examine the relationship between baseline QRS duration and mortality reduction with ICDs implanted for primary prevention by performing a meta-analysis of all available randomized clinical trials.
  
  
  METHODS
  A systematic literature search of SCOPUS (covering MEDLINE and EMBASE) was conducted for randomized controlled clinical trials involving ICDs. Primary prevention trials of systolic dysfunction that reported all-cause mortality according to subgroups on the basis of baseline QRS duration were included.
  
  
  RESULTS
  A total of four randomized controlled clinical trials enrolling 3561 patients were included. Patients with QRS durations less than 120 ms [n = 2002, hazard ratio 0.78, 95% confidence interval (CI) 0.63-0.96, P = 0.018] and at least 120 ms (n = 1559, hazard ratio 0.59, 95% CI 0.48-0.73, P = 0.0000009) had significant decreases in all-cause mortality. On heterogeneity analysis, a strong trend for greater magnitude of benefit in patients with QRS at least 120 ms was observed (22% risk reduction vs. 41% risk reduction, P = 0.066).
  
  
  CONCLUSIONS
  For primary prevention purposes, ICDs are effective in reducing all-cause mortality in moderate to severe systolic dysfunction regardless of QRS duration. However, patients with a baseline QRS duration of at least 120 ms seem to derive a greater mortality benefit from ICDs.
authors.affiliation: aAcibadem University Medical School, Department of Cardiology, Istanbul, Turkey bHarrington Heart & Vascular Institute, University Hospitals Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio cMayo Clinic, Rochester, Minnesota, USA.
authors.forename: Ilke
authors.initials: I
authors.lastname: Sipahi
authors.forename: Sunit-Preet S
authors.initials: SP
authors.lastname: Chaudhry
authors.forename: Meltiady
authors.initials: M
authors.lastname: Issa
authors.forename: Megha
authors.initials: M
authors.lastname: Ambati
authors.forename: Sinan
authors.initials: S
authors.lastname: Dagdelen
authors.forename: James C
authors.initials: JC
authors.lastname: Fang
mesh_terms: D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D004562:Electrocardiography / Q000379:methods; D006333:Heart Failure / Q000401:mortality / Q000628:therapy; D006801:Humans; D011322:Primary Prevention / Q000379:methods; D011379:Prognosis; D016032:Randomized Controlled Trials as Topic / Q000379:methods