Influence of high ovarian hormones on QT interval duration in young African women

The longer QT interval duration observed in women compared to men is usually attributed to sexual hormones. The aim of our study was to investigate, among black African women, the influence of hormonal variations during the menstrual cycle on the duration of the QT interval. Fourteen young black African women, healthy, sedentary, aged 24 ± 1.7 years, with a regular menstrual cycle (28 ± 1 days) were selected from 59 volunteers. At each phase of their menstrual cycle, menstrual 2.9 ± 0.6 days, follicular 13 ± 1.5 days, and luteal 23.1 ± 1.4 days, an electrocardiogram was performed in supine position after a resting period of 30 min, to measure QT interval duration. QT interval was corrected by Bazett's (QTc(b)) and Fridericia's (QTc(f)) formulae. Then, blood samples were obtained to measure estradiol, progesterone, and serum electrolytes (K(+), Ca(2+), Mg(2+)). There was no significant difference in uncorrected QT intervals between the three phases of the menstrual cycle. It was the same for QTc(b) and QTc(f). Moreover, during the menstrual cycle, we did not observe any correlation between each QT, QTc(b), QTc(f), and estradiol levels which raised during the follicular phase (356.61 ± 160.77 pg/mL) and progesterone levels which raised during the luteal phase (16.38 ± 5.88 ng/mL). Finally, the method of Bland and Altman demonstrated that the corrections of QT by Bazett and Fridericia formulae were not interchangeable. The results of this study showed that high levels of estradiol and progesterone in young black African women did not influence the QT, QTc(b) and QTc(f) intervals duration during the menstrual cycle.