Tpeak-Tend Interval and its Derivatives as Indices of Repolarization Dispersion and Arrhythmic Risk: Traditional Review

Development of life-threatening ventricular arrhythmias is often associated with an increase in the dispersion of ventricular repolarization (DOR), which can be detected by electrocardiographic (ECG) methods. For several decades, there was an active search for ECG markers reflecting the magnitude of DOR and the associated arrhythmic risk. The interval from the peak to the end of the T-wave (Tpe) was found to be the most accurate measure of DOR and a reliable marker of arrhythmic risk in various cardiac disorders. In addition to Tpe interval itself, its derivatives-Tpe dispersion and Tpe/QT ratiowere proposed as arrhythmic risk markers. In this review, several aspects regarding Tpe and its derivatives are discussed: (1) physiological rationale for relationship to DOR and arrhythmic risk, (2) clinical significance for predicting ventricular arrhythmias, and (3) clinical limitations. Based on the experimental, clinical and simulation studies, the review demonstrates that Tpe, dTpe and Tpe/QT ratio are informative concerning both the global and the local DOR. They are significant predictors of arrhythmias associated with increased DOR, and the overall mortality. Besides, Tpe magnitude showed itself as a simple, non-invasive, inexpensive and quick indirect assessment of hemodynamic and volumetric ventricular parameters, the extent and severity of coronary artery stenosis, therapy response and the expected hospital stay. However, the lack of consensus in measurements led to large variations of cut-off values reported by different researchers. The inclusion of Tpe in routine ECG analysis requires further research based on the more unified measurements, including machine learning and artificial intelligence tools.