Variation of the T-wave peak-end interval and heart rate variability values in healthy males and females at various hours of the same day, and relationship of them.

Background: The prolongation of repolarization time between the myocardial epicardium and endocardial cells is closely related to malignant ventricular arrhythmias. The purpose of our study was to compare repolarization markers, namely, T-wave peak-end interval (Tp-e), QT, corrected QT (QTc), Tp-e/QT, Tp-e/corrected QT (QTc), and Heart Rate Variability (HRV) values in healthy men and women and to investigate their daily variations.

Methods: A total of 74 male and 78 female participants, being a government employee, and having no health problems, were included in the two study groups (males and females). A 24-hour, 12-lead Holter monitoring was performed on the volunteers. Then, the Tp-e interval and QT interval were measured on recordings. cTp-e and QTc were calculated by the use of Bazzet's formula.

Results: There was no statistically significant difference between the groups in the cTp-e interval at 07.00 pm; however, it was significantly lower in the female group as compared with the male group at 07.00 am and 01.00 pm. It was significantly higher in the female group at 01.00 am compared with the male group. There were statistically significant moderate negative correlations between Tp-e intervals and a standard deviation of between two normal beats interval (SDNN) values at various hours of the same day.

Conclusion: There were statistically significant differences in terms of Tp-e and cTp-e intervals at various hours of the same day in both groups. In addition, there were statistically significant moderate negative correlations between Tp-e intervals and SDNN at various hours of the same day.