Scenarios for Increasing, Decreasing and Stability of Tpe/QT Ratio (Simulation Study)

The objective of this simulation was to study the physiological meaning of the novel index for arrhythmic risk stratification – Tpe/QT ratio (the interval from the peak to the end of the T-wave (Tpe) on electrocardiogram divided by QT interval). Methods and Results: The role of two factors determining Tpe/QT ratio – action potential duration (APD) and dispersion of repolarization (DOR) – was studied in silico at two levels: ventricular wall segment and the whole heart ventricles. The simulations performed in the framework of both the segment and the entire ventricles’ models showed that Tpe/QT magnitude reflects the dynamic relationship between the longest and the shortest APD rather than the magnitude of DOR, as interval Tpe does. Tpe/QT ratio remained unchanged even at large DOR, provided that the longer the ventricular APD, the greater the gap between the longest and the shortest of them. The imbalance between the longest and the shortest APD values led to the increased or decreased Tpe/QT. Conclusion: Simulations showed that Tpe/QT is not just a corrected Tpe interval, but it reflects the balance between the longest and the shortest APD in the heart ventricles.