title: A prospective evaluation of the risk of QT prolongation with hormone replacement therapy: the atherosclerosis risk in communities study.
abstract: OBJECTIVE
  Prolongation of the QT interval is associated with an increased risk of arrhythmia, coronary heart disease (CHD), and mortality. Estrogens and androgens have been proposed as a causal factor in QT lengthening. We tested whether postmenopausal hormone replacement therapy was associated with prolonged QT intervals in a healthy population sample of women (mean age=54).
  
  
  METHODS
  Women (n=3103) were asked about estrogen (ERT) and progestin plus estrogen (PERT) replacement therapy use at 4 examinations over 9 years. Electrocardiographic QT intervals were measured and corrected for heart rate using the QT Index (QTI) and Bazett's correction. QT prolongation was defined as QTI>110% and a change from baseline of >or=4%.
  
  
  RESULTS
  Heart rate corrected QT length was moderately but significantly (p<0.01) greater, and the risk of QT prolongation was nearly twice (Odds Ratio=1.9, 95% Confidence Interval: 1.2-2.0) that in women who used ERT compared with never users. PERT use was not significantly associated with QT length.
  
  
  CONCLUSIONS
  The potential for slight increases in QT length over time, and an increased risk of QT prolongation with ERT use identified in this observational study, are important concerns that should be further explored in randomized trials.
authors.affiliation: Stanford Center for Research in Disease Prevention, Stanford University School of Medicine, Palo Alto, CA, USA. carnethon@northwestern.edu
authors.forename: Mercedes R
authors.initials: MR
authors.lastname: Carnethon
authors.forename: Mary S
authors.initials: MS
authors.lastname: Anthony
authors.forename: Wayne E
authors.initials: WE
authors.lastname: Cascio
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Folsom
authors.forename: Pentti M
authors.initials: PM
authors.lastname: Rautaharju
authors.forename: Duanping
authors.initials: D
authors.lastname: Liao
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Evans
authors.forename: Gerardo
authors.initials: G
authors.lastname: Heiss
mesh_terms: D001161:Arteriosclerosis / Q000209:etiology; D015331:Cohort Studies; D004562:Electrocardiography; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008133:Long QT Syndrome / Q000139:chemically induced* / Q000150:complications / Q000503:physiopathology; D008137:Longitudinal Studies; D008875:Middle Aged; D011446:Prospective Studies; D014481:United States