Tp-e/QT ratio and QT dispersion with respect to blood pressure dipping pattern in prehypertension.

Introduction: Tp-e/QT, the ratio of the interval between the peak and the end of T wave to the QT interval, is a novel index of arrhythmogenesis. We investigate Tp-e/QT and QT dispersion (QTd) in prehypertensive and normotensive patients with different patterns of nocturnal blood pressure dipping.

Patients And Methods: Forty-seven prehypertensive and 37 normotensive adult patients were included. Ambulatory blood pressure monitoring recording was performed and patients were considered to be dipper if nocturnal blood pressure fall was at least 10%; nondipper if it was 0-10%; and reverse-dipper if less than 0%. Tp-e, QT intervals were assessed by 12-lead ECG and Tp-e/QT was calculated using these measurements. QTd is defined as the difference between the maximum and the minimum QT interval of the 12 leads.

Results: Tp-e/QT was 0.22±0.02 and 0.16±0.01 in prehypertensives and normotensives, respectively (P<0.001), whereas cQTd was 36.1±6.8 and 27.2±5.2 ms (P<0.001). Tp-e and Tp-e/QT were the lowest in the dippers and the highest in the reverse-dippers in the prehypertensive group (Tp-e/QT dipper: 0.21±0.01; nondipper: 0.24±0.02; reverse-dipper: 0.25±0.01; for dipper-nondipper, and dipper-reverse-dipper P<0.05). However, in the normotensive group, dipping status had no effect on Tp-e/QT. There were no significant differences between dippers, nondippers, and reverse-dippers in terms of cQTd both in prehypertensives and in normotensives. There were no associations between left ventricular mass index and Tp-e, Tp-e/QT, and cQTd in both groups.

Conclusion: Tp-e, Tp-e/QT, and cQTd are increased in prehypertensives compared with normotensives. Tp-e and Tp-e/QT are associated with the dipping status in prehypertensives.