Effects of Long-Term Hormone Replacement Therapy on QT and Corrected QT Dispersion during Resting and Peak Exercise Electrocardiography in Post-Menopausal Women.

Abstract

SUMMARYIt is known that the QT interval is longer in women than men. Estrogen is reported to account for the QT interval prolongation in several studies conducted with hormone replacement therapy (HRT) in postmenopausal women. Along with this, there are conflicting data as regards the effects of HRT on QT interval and dispersion. Moreover, there is no evidence about the effect of HRT on exercise QT parameters.We compared QT parameters obtained from surface electrocardiograms during resting and peak exercise before and after 6 months of HRT consisting of estrogen plus progesterone in healthy postmenopausal women. Twenty-four healthy postmenopausal women were given 0.625 mg/day conjugated estrogens and 2.5 mg/day medroxyprogesterone acetate for 6 months. Exercise stress testing using the Bruce protocol was performed before and after HRT. QT maximum, minimum, dispersion and corrected QT maximum, minimum and dispersion were calculated during resting and peak exercise.HRT resulted in a significant increase in estradiol plasma levels from 24±10 pg/mL to 117±66 pg/mL (P<0.001). There was no significant difference in resting QT parameters after HRT, whereas QT dispersion and corrected QT dispersion were significantly increased during peak exercise (20±7 versus 25±10 ms; P<0.05, 33±12 versus 41±16 ms; P<0.05, respectively). Nonetheless, the other exercise QT parameters were unchanged.The resting QT parameters are not affected by long term HRT consisting of estrogen plus progesterone, which leads to an increase in QT dispersion and corrected QT dispersion during peak exercise. (Jpn Heart J 2002; 43: 1-7)

Estrogen Contributes to Gender Differences in Mouse Ventricular Repolarization

“…Hormone replacement therapy with estrogen alone significantly prolonged QTc interval22,23, whereas combined estrogen and progestin therapy had no effect24 or reduced the QTc interval23, 25. These findings suggest that sex hormones may directly modulate ventricular repolarization; estrogen is reported to account for the prolongation of QTc interval similar to our results in mice whereas progesterone tends to reduce QTc interval.…”

Electrical Storms after Levonorgestrel (Synthetic Progestin)-Releasing Intra-Vaginal Device Insertion. A Case Report and a Short Review of Literature

“…As a result, it was stated that HRT including estrogen plus progesterone homogenized the QT duration and therefore decreased the QTd. Spatial homogenization of ventricular repolarization by progesterone may be explained by a direct and nongenomic action of progestagens on myocardial conduction velocities, as previously reported in neuronal Open Journal of Obstetrics and Gynecology tissue [16] [17]. This highlights the need to take into account synthetic progesterone, as well as estrogen, when evaluating hormonal effects on repolarization in women.…”

Relationship between QT interval and cardiovascular risk factors in healthy young subjects

“…36 Hormonal factors may contribute to sex differences in ventricular repolarization, although data on the effects of oestrogens and progesterone on QT interval and dispersion are not univocal. 37,38 The significantly higher blood pressure we found in male subjects may also have contributed to the sex differences in the relationship between blood pressure and QTc duration.…”