Variability of Ventricular Repolarization Dispersion Quantified by Time-Warping the Morphology of the T-Waves.

Objective: We propose two electrocardiogram (ECG)-derived markers of T-wave morphological variability in the temporal, d_w, and amplitude, d_a, domains. Two additional markers, d_w^\mathrmNL and d_a^\mathrmNL, restricted to measure the nonlinear information present within d_w and d_a are also proposed. Methods: We evaluated the accuracy of the proposed markers in capturing T-wave time and amplitude variations in 3 situations: 1) In a simulated set up with presence of additive Laplacian noise, 2) when modifying the spatio-temporal distribution of electrical repolarization with an electro-physiological cardiac model, and 3) in ECG records from healthy subjects undergoing a tilt table test. Results: The metrics d_w, d_a , and d_a^{\mathrm{NL}} followed T-wave time- and amplitude-induced variations under different levels of noise, were strongly associated with changes in the spatio-temporal dispersion of repolarization, and showed to provide additional information to differences in the heart rate, QT$ and T_{\mathrm{pe}} intervals, and in the T-wave width and amplitude. Conclusion: The proposed ECG-derived markers robustly quantify T-wave morphological variability, being strongly associated with changes in the dispersion of repolarization. Significance: The proposed ECG-derived markers can help to quantify the variability in the dispersion of ventricular repolarization, showing a great potential to be used as arrhythmic risk predictors in clinical situations. [ABSTRACT FROM AUTHOR]