title: Hormone replacement therapy shortens QT dispersion in healthy postmenopausal women.
abstract: BACKGROUND
  The aim of the study was to investigate the effects of hormone replacement therapy (HRT) on myocardial repolarization characteristics in postmenopausal women without coronary artery disease.
  
  
  METHODS
  Fifty-one consecutive healthy postmenopausal women (age 48 +/- 5) with negative exercise stress testing were prospectively enrolled into the study. Standard 12-lead electrocardiograms were obtained to evaluate the effects of 6 months of HRT on QT intervals, corrected QT intervals (QTcmax and QTcmin), QT dispersion (QTd), and corrected QTd (QTcd). Hormone regimens were continuous 0.625 mg/day conjugated equine estrogen (CEE) plus 2.5 mg/day medroxyprogesterone acetate (MPA) or 0.625 mg/day CEE alone depending on the hysterectomy status.
  
  
  RESULTS
  Although not statistically significant, CEE alone or in combination with MPA increased QTmax and QTmin values. However, the increase in QTmin was greater than the increase in QTmax, which resulted in statistically significant shortening of QTd (P = 0.007 in CEE and P < 0.001 in CEE + MPA groups). There was a significant prolongation of QTcmin values after 6 months in patients assigned to the CEE group (P = 0.001). The QTcd values were significantly shortened by HRT with both regimens (for CEE group 49 +/- 13 ms vs 38 +/- 13 ms, P = 0.01; for CEE + MPA group 49 +/- 14 ms vs 36 +/- 13, P < 0.001).
  
  
  CONCLUSIONS
  HRT significantly decreased the QTd and QTcd in postmenopausal women without coronary artery disease, independent of the addition of MPA to the regimen. This improvement in myocardial repolarization may be one of the mechanisms of the favorable effects of HRT on cardiovascular system. However, the clinical implications of the shortening of QTd in postmenopausal women with HRT must be clarified.
authors.affiliation: Hacettepe University Department of Cardiology, Ankara, Turkey. ayliny@ato.org.tr
authors.forename: A
authors.initials: A
authors.lastname: Yildirir
authors.forename: F
authors.initials: F
authors.lastname: Aybar
authors.forename: M G
authors.initials: MG
authors.lastname: Kabakci
authors.forename: H
authors.initials: H
authors.lastname: Yarali
authors.forename: E
authors.initials: E
authors.lastname: Akgul
authors.forename: O
authors.initials: O
authors.lastname: Bukulmez
authors.forename: S L
authors.initials: SL
authors.lastname: Tokgozoglu
authors.forename: T
authors.initials: T
authors.lastname: Gurgan
authors.forename: A
authors.initials: A
authors.lastname: Oto
mesh_terms: D000328:Adult; D004562:Electrocardiography / Q000187:drug effects*; D015914:Estrogen Replacement Therapy; D004966:Estrogens, Conjugated (USP) / Q000627:therapeutic use; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D017258:Medroxyprogesterone Acetate / Q000627:therapeutic use; D008875:Middle Aged; D011446:Prospective Studies; D012016:Reference Values; D016387:Women's Health
chemical_list: D004966:Estrogens, Conjugated (USP); D017258:Medroxyprogesterone Acetate