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

Abstract:

Objective: We propose two electrocardiogram (ECG)-derived markers of T-wave morphological variability in the temporal, d<inf>ω</inf>, and amplitude, d<inf>α</inf>, domains. Two additional markers, d<inf>ω</inf>NL and d<inf>α</inf>NL, restricted to measure the nonlinear information present within d<inf>ω</inf> and d<inf>α</inf> 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<inf>ω</inf>, d<inf>α</inf>, d<inf>ω</inf>NL, and d<inf>α</inf>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<inf>pe</inf> 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.