Beat-to-beat T-peak T-end interval duration variability assessed by RR-interval histogram analysis in health sedentary and athlete

Abstract

Ventricular repolarization duration (VRD) to RR-interval coupling relates to autonomic control and myocardial electrical stability. T-peak to T-end (TpTe) interval defined as the interval between the peak and the end of the T wave is an index of transmural dispersion of repolarization (TDR) with potential clinical implication. However, the dynamic coupling between TpTe- and RR-interval still needs clarification. This study investigated TpTe- and RR-interval coupling to assess dynamic repolarization adaptation in healthy sedentary (Control; n = 10) and well-conditioned male subjects (Athlete; n = 10). Both groups underwent 15 min resting ECG. Supervised fiducial point detection was carried out after low-pass filtering at 15 Hz. Histogram of RR-interval series was calculated, with 100 ms class width, ranging from 600 ms to 1200 ms. For each class, mean of normal RR-intervals (MRR) and mean of the TpTe-interval (MTpTe) were calculated. Regression lines of MTpTe as function of MRR were computed and Student t-test compared slopes between groups (α < 0.05). In Control and Athlete, respectively, MTpTe was 82.2 ± 6.2 ms and 94.4 ± 6.9 ms (p < 0.05) and MRR interval was 849.2 ± 109.1 ms and 1027.5 ± 124.0 ms (p < 0.05). MTpTe significantly increased as a function of MRR in Athlete, whereas, in Control, slope was nonsignificantly negative. In athletes, TpTe-interval increases as a linear function of RR-interval in a wide physiological RR-interval range at rest, whereas, in sedentary subjects, TpTe-interval remained unchanged.