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, dw, and amplitude, da, domains. Two additional markers, dwNL and daNL, restricted to measure the nonlinear information present within dw and da 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 dw, da , dwNL , and daNL 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 Tpe 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.