Effect of body position on the measurements of early and late cardiac repolarization duration

In this study, we assessed the impact of changes in body position on our novel parameters quantifying repolarization heterogeneity based on the morphology of the T-loop. Early and late repolarization durations (ERD and LKD) as well as QT/QTc, RR and T-wave amplitude were computed from the three pseudo-orthogonal lead (X, Y Z) recorded in healthy individuals. These measurements were monitor continuously in 63 individuals undergoing experiment including five body positions: left supine, right supine, supine, standing and sitting. We observed more profound impact of body position changes onto the QT/QTc interval and heart rate than in TpTe, ERD and LRD intervals. We conclude that the ERD and LRD interval measurements are more robust to changes in autonomic balance and heart position triggered by body position shifts.