Influence of Menstrual Cycle on QT Interval Dynamics

Abstract

Objectives:The aim of this study was to investigate the effects of the menstrual cycle on QT interval dynamics and the autonomic tone in healthy women.Methods: Holter ECGs were recorded in 11 healthy women aged 18-32 years during the follicular and luteal phases of their regular menstrual cycle. The interval from QRS onset to the apex (QaT) and to the end of the T-wave (QeT), the interval between the apex and the end of the T-wave (Ta-e), and RR intervals were measured automatically in the course of 24 hours by Holter ECGs. The QeT/RR, QaT/RR, and Ta-e/RR relationships were evaluated in each subject. The autonomic tone was assessed by the serum catecholamine level at rest and heart rate variability was measured by Holter ECGs.Results: (1) The follicular and luteal phases did not differ significantly with respect to the slopes of the QeT/RR, QaT/RR, and Ta-e/RR relationships. However, QeT and QaT intervals were significantly shorter for all RR intervals in the luteal than in the follicular phase (P < 0.0001). (2) The serum progesterone concentration was significantly higher in the luteal than in the follicular phase (P < 0.001). (3) Noradrenaline was significantly higher in the luteal than in the follicular phase (P < 0.05). There was no significant difference in the follicular and luteal phases with respect to heart rate variability measurements.Conclusions: Our results suggest that the menstrual cycle affects the QT intervals. The observed shorter QT interval during the luteal than the follicular phase may be attributable to the increase in serum progesterone and sympathetic tone. (PACE 2006; 29:607-613) QT interval, menstrual cycle, sex hormone, gender difference, QT/RR relationship, autonomic tone IntroductionPrevious studies have reported a gender difference in the incidence of various types of ventricular arrhythmias. Torsades de pointes associated with long QT syndrome is more common in women than in men, 1-3 whereas the incidence of Brugada syndrome 4 or sudden death 5 is higher in men than in women. We reported that genderspecific differences exist in the incidence of various types of idiopathic ventricular tachycardia (VT) and that VT originating from the right ventricular outflow tract (RVOT) is more common in women than in men. 6 It is important to consider the potential significance of endogenous, menstrual cycle-related sex hormones in various cardiovascular diseases. 7,8 The early follicular phase, during which serum estrogen is at its lowest level in the menstrual cycle, might be a time when premenopausal women with coronary artery disease are particularly susceptible to ischemic events. 7,8 On the other hand, Marchlinski et al. 9 reported that the hormonal flux that occurs during pre-

Pediatric Cohort With Long QT Syndrome – <i>KCNH2</i> Mutation Carriers Present Late Onset But Severe Symptoms –

“…24 Although electrophysiological experiments using a guinea pig model showed that estrogen prolongs the action potential duration (APD) through the inhibition of IKr, 25 the effect of estrogen on QT interval in humans remains controversial. 26 Progesterone shortens APD, which is mainly attributable to the enhancement of IKs under basal conditions and the inhibition of ICaL under cAMP stimulation, and a computer simulation model using a 50% IKr block indicated a protective effect of progesterone against arrhythmia.…”

New Aspects for the Treatment of Cardiac Diseases Based on the Diversity of Functional Controls on Cardiac Muscles: Acute Effects of Female Hormones on Cardiac Ion Channels and Cardiac Repolarization

“…Although several previous studies did not find QT C -interval differences among the different menstrual phases (21,28,29), a recent study analyzing various parameters of cardiac repolarization found that repolarization duration is shorter in the luteal phase than in the follicular phase by about 10 ms (30). The susceptibility of drug-induced arrhythmias also fluctuates considerably during the menstrual cycle in women: the QT C prolongation induced by ibutilide, a class III antiarrhythmic agent, is greatest during menses, intermediate at ovulation, and least in the luteal phase, in which progesterone level is highest (28).…”

Reduced parasympathetic activity during sleep in the symptomatic phase of severe premenstrual syndrome

“…There are reports of increases in the LF/HF ratio, interpreted as indicating increased SNS activity (14-16), increased HF power, interpreted as indicating enhanced PNS activity (17), decreased SDNN and SDANN (12), or no change in time-domain (18) or spectral-domain (19) HRV components during the luteal phase compared with the follicular phase of the menstrual cycle.…”