Quantification of t-wave morphological variability using time-warping methods

Abstract

The aim of this study is to quantify the variation of the T-wave morphology during a 24-hour electrocardiogram (ECG) recording. Two ECG-derived markers are presented to quantify T-wave morphological variability in the temporal, dw, and amplitude, da , domains. Two additional markers, dwNL and daNL , that only capture the non-linear component of dw and da are also proposed. The proposed markers are used to quantify T-wave time and amplitude variations in 500 24-hour ECG recordings from chronic heart failure patients. Additionally, two mean warped T-waves, used in the calculation of those markers, are proposed to compensate for the rate dependence of the T-wave morphology. Statistical analysis is used to evaluate the correlation between dw, dwNL , da and daNL and the maximum intra-subject RR range, ∆RR. Results show that the mean warped T-wave is able to compensate for the morphological differences due to RR dynamics. Moreover, the metrics dw and dwNL are correlated with ∆RR, but da and daNL are not. The proposed dw and dwNL quantify variations in the temporal domain of the T-wave that are correlated with the RR range and, thus, could possibly reflect the variations of dispersion of repolarization due to changes in heart rate.