title: Long term effects of hormone replacement therapy on heart rate variability, QT interval, QT dispersion and frequencies of arrhythmia.
abstract: BACKGROUND
  The aim of the study was to investigate the effects of a long term (1 year) hormone replacement therapy (HRT) on QT interval, QT dispersion (QTd) frequencies of arrhythmia and heart rate variability (HRV) parameters.
  
  
  METHODS
  Forty-six healthy postmenopausal women (mean age; 55.34+/-4.21) as a hormone replacement therapy group and 25 healthy premenopausal women (mean age; 35.36+/-6.06) as a control group were prospectively enrolled to the study. Hormone replacement therapy group was divided into two groups; estrogen replacement therapy (ERT) group (n=23) and progestin-estrogen replacement therapy (PERT) group (n=23). Standard 12 lead electrocardiograms and 24-h ambulatory Holter recording were obtained to evaluate the effects of one year of ERT and PERT on QT intervals, QTd, frequencies of arrhythmias and HRV parameters.
  
  
  RESULTS
  Long term use of ERT increases QT interval, QTd, in the frequencies of arrhythmia and HRV indexes of parasympathetic activity; however, the increase in frequencies of arrhythmia was not statistically significant (p>0.05). Long term use of PERT did not effected QT interval, QTd, frequencies of ventricular arrhythmia and HRV parameters (p>0.05). Frequency of supraventricular tachycardia increased in post-treatment PERT group was compared with pre-treatment PERT group.
  
  
  CONCLUSIONS
  These findings supported the hypothesis that estrogen may directly modulate ventricular repolarization. But progestin do not effect the ventricular repolarization. However, these findings must be supported with a large-scale study.
authors.affiliation: Department of Cardiology, Karadeniz Technical University, Trabzon 61080, Turkey. mustgokce@ahoo.com
authors.forename: Mustafa
authors.initials: M
authors.lastname: Gökçe
authors.forename: Burhan
authors.initials: B
authors.lastname: Karahan
authors.forename: Remzi
authors.initials: R
authors.lastname: Yilmaz
authors.forename: Cihan
authors.initials: C
authors.lastname: Orem
authors.forename: Cevdet
authors.initials: C
authors.lastname: Erdöl
authors.forename: Safak
authors.initials: S
authors.lastname: Ozdemir
mesh_terms: D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects*; D006339:Heart Rate; D006801:Humans; D008875:Middle Aged; D011372:Progestins / Q000502:physiology; D011446:Prospective Studies; D013997:Time Factors; D016276:Ventricular Function
chemical_list: D004967:Estrogens; D011372:Progestins