Mental stress induced corrected QT interval changes in the milieu of a normal menstrual cycle

Introduction and Aim: Corrected QT interval (QTc) values are consistently different between males and females, and sex hormones are the likely causative agents for this. The aim of the present study was to study the effect of different phases of menstrual cycle on QTc at resting conditions, as well as when exposed to mental stress in young healthy females. Materials and Methods: ECG recordings of 28 healthy women in the age group of 18-25 years were used for QTc estimation using Bazett's formula. The mean values of QTc obtained during the follicular and luteal phases of the menstrual cycle, both during resting conditions as well as during mental stress were statistically analyzed using paired t-test and significance were set at P<0.05. Results: In this study, the QTc values during resting as well as the mental stress task were similar in both phases of the menstrual cycle and were statistically not significant. The mental stress task (serial subtraction task) as such produced a significant prolongation of the QTc values in both the follicular (p < 0.01) as well as the luteal phases (p < 0.001) when compared to the basal values in the respective phases. But the change in QTc values due to mental stress intervention i.e. ΔQTc was similar in both the phases and was not significant. Conclusion: Resting QTc values did not vary during the different phases of the menstrual cycle, and mental stress produced the anticipated increase in QTc values, but even these were similar during the follicular and luteal phases.