title: Determinants of prolonged QT interval and their contribution to sudden death risk in coronary artery disease: the Oregon Sudden Unexpected Death Study.
abstract: BACKGROUND
  In a recent cohort study, prolongation of the corrected QT interval (QTc) was associated with an independent increased risk of sudden cardiac death (SCD). We evaluated determinants of prolonged QTc and the relationship of prolonged QTc to SCD risk among patients with coronary artery disease in the general population.
  
  
  RESULTS
  A case-control design was used. Cases were SCD patients with coronary artery disease among a metropolitan area of 1 000 000 residents (2002 to 2006); controls were area residents with coronary artery disease but no history of SCD. All cases were required to have an ECG suitable for QTc analysis before and unrelated to the occurrence of SCD. A total of 373 cases and 309 controls met criteria for analysis. Mean QTc was significantly longer in cases than in controls (450+/-45 versus 433+/-37 ms; P<0.0001). In a multivariate model, gender, diabetes mellitus, and QTc-prolonging drugs were significant determinants of QTc prolongation in controls. In a logistic regression model predicting SCD, diabetes mellitus (odds ratio, 1.97; 95% confidence interval, 1.32 to 2.96) and use of QTc-prolonging drugs (odds ratio, 2.90; 95% confidence interval, 1.92 to 4.37) were significant predictors of SCD among subjects with normal or borderline QTc. However, abnormally prolonged QTc in the absence of diabetes and QT-prolonging medications was the strongest predictor of SCD (odds ratio, 5.53; 95% confidence interval, 3.20 to 9.57).
  
  
  CONCLUSIONS
  Diabetes mellitus and QTc-affecting drugs determined QTc prolongation and were predictors of SCD in coronary artery disease. However, idiopathic abnormal QTc prolongation was associated with 5-fold increased odds of SCD. A continued search for novel determinants of QTc prolongation such as genomic factors is likely to enhance risk stratification for SCD in coronary artery disease.
authors.affiliation: Cardiac Arrhythmia Center, Division of Cardiovascular Medicine, Oregon Health and Science University, Portland, USA. sumeet.chugh@cshs.org
authors.forename: Sumeet S
authors.initials: SS
authors.lastname: Chugh
authors.forename: Kyndaron
authors.initials: K
authors.lastname: Reinier
authors.forename: Tejwant
authors.initials: T
authors.lastname: Singh
authors.forename: Audrey
authors.initials: A
authors.lastname: Uy-Evanado
authors.forename: Carmen
authors.initials: C
authors.lastname: Socoteanu
authors.forename: Dawn
authors.initials: D
authors.lastname: Peters
authors.forename: Ronald
authors.initials: R
authors.lastname: Mariani
authors.forename: Karen
authors.initials: K
authors.lastname: Gunson
authors.forename: Jonathan
authors.initials: J
authors.lastname: Jui
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003324:Coronary Artery Disease / Q000401:mortality*; D016757:Death, Sudden, Cardiac / Q000453:epidemiology*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D016015:Logistic Models; D008133:Long QT Syndrome / Q000175:diagnosis* / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D009922:Oregon / Q000453:epidemiology; D011237:Predictive Value of Tests; D012307:Risk Factors