Evaluation of T-wave Time-Warping Dynamics in Patients with Long QT Syndrome.

In this work, we use a T-wave time-warping-based morphology variation index, $d_{w}$, quantifying ventricular repolarization dispersion (VRD), and assess its performance in classifying long QT syndrome (LQTS) patients and healthy control (CG) individuals, as well as LQTS patients who experienced syncope (LQTS-SG) and those who did not (LQTSNSG). The values of $d_{w}$ were obtained by quantifying the morphological differences between the mean warping T-wave (MWTW), estimated from each 10-second ECG recording and a reference MWTW estimated from the UK Biobank cohort. In CG, $d_{w}$ had median (IQR) values of 9.32 (5.53) $\mathbf{m s}$, while larger changes were noted in LQTS patients, with median (IQR) values of 20.93 (12.67) ms. Neither $d_{w}$ nor the QT interval presented significant differences when comparing LQTS-SG and LQTSNSG. A p-value near significance was found for $d_{w}$ in lead II. $d_{w, \mathrm{~T}_{p e}}$ marker, restricting the analysis to the final T-peak to Tend part, reached significance when comparing LQTS-SG with LQTS-NSG in Lead I. In conclusion, larger $d_{w}$ values in LQTS patients as compared to CG allows LQTS idnetification more significnatly than QT interval. Distintion between LQTS-SG and LQTS-NSG patients becomes unconclusive, both with $d_{w}$ and $d_{w, T_{p e}}$ as well as QT interval suggesting further work.