title: Race and gender variation in the QT interval and its association with mortality in patients with coronary artery disease: results from the Duke Databank for Cardiovascular Disease (DDCD).
abstract: BACKGROUND
  In several studies, prolongation of the corrected QT (QTc) interval has been associated with an increased risk of cardiac events. However, data on race and gender variation in the QTc and its associated risk of death are lacking.
  
  
  METHODS
  We prospectively followed 19,252 subjects who underwent cardiac catheterization and had at least 1 native coronary artery stenosis ≥75%. Automated QTc measurements were obtained from a baseline electrocardiogram.
  
  
  RESULTS
  The mean age of the population was 62.4 years, with 35% being female and 20% being black. The QTc varied by gender and race (417.9 ± 34.4 ms in men and 433.4 ± 33.6 ms in women, 422.1 ± 34.3 ms in whites and 428.1 ± 36.9 ms in blacks; P < .0001 for both). Risk factors most strongly associated with a prolonged QTc were lower ejection fraction, higher diastolic blood pressure, history of myocardial infarction, and lower glomerular filtration rate. Black race and female gender were also independently associated with a prolonged QTc, after adjustment for cardiac risk factors. Moreover, there was an independent association between QTc and all-cause mortality (hazard ratio 1.037 per 10-ms increase, P < .0001). The increased mortality risk associated with a 10-ms increase in the QTc interval was significantly greater for men compared with women (4.6% vs 2.4%, P = .004) and slightly greater for blacks compared with other races (5.0% vs 3.3%, P = .057).
  
  
  CONCLUSIONS
  Among patients with coronary artery disease, QTc prolongation is independently associated with all-cause mortality. The increased mortality risk is higher for men than for women, with a trend toward higher mortality in blacks.
authors.affiliation: Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC, USA.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Williams
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Thomas
authors.forename: Samuel
authors.initials: S
authors.lastname: Broderick
authors.forename: Linda K
authors.initials: LK
authors.lastname: Shaw
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Velazquez
authors.forename: Sana M
authors.initials: SM
authors.lastname: Al-Khatib
authors.forename: James P
authors.initials: JP
authors.lastname: Daubert
mesh_terms: D000368:Aged; D044383:Black People; D006328:Cardiac Catheterization; D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000208:ethnology / Q000401:mortality*; D016208:Databases, Factual; D004562:Electrocardiography; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008133:Long QT Syndrome / Q000208:ethnology / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D016016:Proportional Hazards Models; D011446:Prospective Studies; D044469:Racial Groups; D012307:Risk Factors; D012737:Sex Factors