Estrogen effect on heart rate variability in hypertensive postmenopausal women.
Healthy postmenopausal women and hypertensive patients show an imbalance in the modulation of autonomic nervous control of the cardiovascular system, which may increase the cardiovascular risk.


OBJECTIVE
To examine the heart rate variability (HRV) response to estrogen replacement therapy (ERT) and its association with changes in metabolic variables in hypertensive postmenopausal women.


METHODS
A double-blind, placebo-controlled clinical trial was conducted in 30 hypertensive postmenopausal women receiving 180 mg/day of verapamil. The experimental group (n=16) received 0.625 mg OD of natural conjugated estrogens during 4 months, while control group (n=14) received a placebo. Lipids, lipoproteins, apolipoproteins, glucose and insulin were measured at 0, 2 and 4 months. HRV was determined in time and frequency domains using a 24-h Holter before and after ERT.


RESULTS
Significant higher values of spectral and non-spectral parameters of HRV, associated with a lower LF/HF ratio, were found at the end of 4 months of ERT. Multiple regression analysis revealed that estrogen treatment itself and changes in total cholesterol, LDL-cholesterol, glucose and waist circumference, contributed to the changes observed in indexes reflecting parasympathetic activity in time and frequency domains.


CONCLUSIONS
We conclude that ERT partially improves HRV favoring increased parasympathetic drive, and that part of the effect may be mediated by changes in metabolic variables.
Rosa Brito-Zurita
Olga
O
Hospital de Cardiología del CMN Siglo XXI, Instituto Mexicano del Seguro Social, Mexico D.F.
Posadas-Romero
Carlos
C
Hermosillo
Antonio G
AG
Zamora-González
José
J
Hernández-Ono
Antonio
A
Cardoso-Saldaña
Guillermo
G
Torres-Tamayo
Margarita
M
D000368:Aged; D002121:Calcium Channel Blockers / Q000627:therapeutic use; D004311:Double-Blind Method; D015716:Electrocardiography, Ambulatory; D015914:Estrogen Replacement Therapy; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D008875:Middle Aged; D017698:Postmenopause; D012044:Regression Analysis; D014700:Verapamil / Q000627:therapeutic use
D002121:Calcium Channel Blockers; D014700:Verapamil