The effects of supraphysiological oestrogen levels on ventricular repolarisation parameters.

BACKGROUND: The frequency of arrhythmic death developing without a structural cardiac disease is higher in women. Also, female sex is an independent risk factor regarding development of torsades de pointes. Several studies have been conducted on the physiological and therapeutic effects of sex hormones on the cardiac conduction system. AIM: In this study we aim to examine the effect of hormonal changes, especially supraphysiological E2 level changes occurring during in vitro fertilisation treatment, on ventricular repolarisation parameters. METHODS: The study included female patients aged between 23 and 39 years, who were administered controlled ovarian hyperstimulation treatment. Patients' electrocardiograms and blood samples were obtained and analysed before and after the ovarian hyperstimulation treatment. RESULTS: Mean QTc intervals before ovarian hyperstimulation were 411.9 ± 23.7 ms. Measurements during oestradiol peak were calculated as 420.7 ± 23.3 ms, and the QTc interval increase was significant (p = 0.007). Corrected QT dispersion averages were not significant before or after hyperstimulation (53 ± 17 ms vs. 54.5 ± 18.2 ms, respectively, p > 0.05). Tp-e, J-T peak, and PR dispersion changes were not significant after the ovarian hyperstimulation therapy. CONCLUSIONS: Supraphysiological oestradiol levels that occur during controlled ovarian hyperstimulation cause prolongation of QTc intervals, but not to a pathological level. Although this prolongation is not significant in healthy individuals, it might increase ventricular arrhythmia risk in patients with congenital long QT syndrome and in patients taking medication that prolongs QT.

The Effects of Female Sex Hormones on Ventricular Premature Beats and Repolarization Parameters in Physiological Menstrual Cycle.

BACKGROUND: The effects of gender difference on cardiac electrophysiology have been well studied. In this study, we aimed to evaluate the effects of estradiol and progesteron changes occuring in physiological menstrual cycle on ventricular premature beats (VPBs) and cardiac repolarization parameters. METHODS: Women of reproductive age with VPBs were included into the study group and healthy women were recruited as the control group. During the menstruation period, a 12-lead electrocardiography, blood samples, and 24-hour rhythm Holter were applied to the study group. Similarly, all tests were repeated in the estimated ovulation period (12-14 days before menstruation) by all cases. RESULTS: The study group consisted of 20 women patients with VPB, and the control group of 18 healthy women. While the number of VPB in the menstruation period was 210 beats/day (interquartile range [IQR]: 1,144), it decreased to 86 beats/day (IQR: 251) in the ovulation period with statistical significance (P < 0.05). Average heart rate in the menstruation period was 81.4 ± 10 beats/min and it significantly increased to 84.6 ± 8 beats/min in the ovulation period (P < 0.05). There were no differences in cardiac repolarization parameters in both menstruation and ovulation periods between the study and control groups. Comparing the menstruation and the ovulation periods, J-Tpeak interval, which reflects early repolarization, was shorter in the ovulation period (193 ± 27.7 ms and 201.1 ± 28.6 ms, respectively; P < 0.05). Other repolarization parameters did not show any significant difference. CONCLUSION: VPB frequency decreases with estradiol peak in the ovulation period. This suggests that estrogen may have protective effects against ventricular arrhythmias.