title: Electrocardiographic QT interval and mortality: a meta-analysis.
abstract: BACKGROUND
  Extremely abnormal prolongation of the electrocardiographic QT interval is associated with malignant ventricular arrhythmias and sudden cardiac death. However, the implications of variations in QT-interval length within normal limits for mortality in the general population are still unclear.
  
  
  METHODS
  We performed a meta-analysis to investigate the relation of QT interval with mortality endpoints. Inverse-variance weighted random-effects models were used to summarize the relative risks across studies. Twenty-three observational studies were included.
  
  
  RESULTS
  The pooled relative risk estimates comparing the highest with the lowest categories of QT-interval length were 1.35 (95% confidence interval = 1.24-1.46) for total mortality, 1.51 (1.29-1.78) for cardiovascular mortality, 1.71 (1.36-2.15) for coronary heart disease mortality, and 1.44 (1.01-2.04) for sudden cardiac death. A 50 milliseconds increase in QT interval was associated with a relative risk of 1.20 (1.15-1.26) for total mortality, 1.29 (1.15-1.46) for cardiovascular mortality, 1.49 (1.25-1.76) for coronary heart disease mortality, and 1.24 (0.97-1.60) for sudden cardiac death.
  
  
  CONCLUSIONS
  We found consistent associations between prolonged QT interval and increased risk of total, cardiovascular, coronary, and sudden cardiac death. QT-interval length is a determinant of mortality in the general population.
authors.affiliation: Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA.
authors.forename: Yiyi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wendy S
authors.initials: WS
authors.lastname: Post
authors.forename: Elena
authors.initials: E
authors.lastname: Blasco-Colmenares
authors.forename: Darshan
authors.initials: D
authors.lastname: Dalal
authors.forename: Gordon F
authors.initials: GF
authors.lastname: Tomaselli
authors.forename: Eliseo
authors.initials: E
authors.lastname: Guallar
mesh_terms: D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000401:mortality*; D002318:Cardiovascular Diseases / Q000401:mortality; D003327:Coronary Disease / Q000401:mortality; D016757:Death, Sudden, Cardiac / Q000453:epidemiology; D004562:Electrocardiography; D006801:Humans; D012306:Risk