Brugada syndrome (BrS) is a genetic disorder that affects the ion channels of the cardiac myocites, resulting in a higher predisposition to malignant ventricular arrhythmias and sudden cardiac death (SCD). Risk stratification and management of BrS patients remains a major clinical challenge. In this work, we use a time-warping-based index of the T wave peak to end morphological restitution (TPEMR) to quantify the restitution properties of the late phase of ventricular repolarization and evaluate its ability to distinguish between control and BrS patients and between symptomatic (BrS-S) and asymptomatic patients (BrS-A).
The original TPEMRO index was computed from 24-hour Hoter ECG recordings of 89 BrS patients (29 asymptomatic, BrS-A, 60 symptomatic, BrS-S) and 32 healthy control patients. TPEMR quantifies morphological differences in T-peak-to-end area between two average T waves at different RR values per RR increment. It is obtained from the time-warping dw,Tpe index computed from two mean warped T-peak-to-end waves corresponding to two distant RR bins. TPEMR obtained after applying two different strategies of weighted warping, TPEMRW1 and TPEMRW2, were also computed to gain robustness against delineation errors.
TPEMRO, TPEMRW1 and TPEMRW2 indices were significantly higher for the BrS group than for the control group (Kruskal-Wallis test), with values of 0.009, 0.007 and 0.004 vs 0.006, 0.005 and 0.002, with p-values of 0.014, 0.009 and 0.010, respectively. Pacients in the BrS-S group presented higher TPEMR indexes than those in BrS-A group for all indices, but significance was restricted to TPEMRW2 index (0.004 vs 0.003, p=0.024).
The T peak to end morphology restitution index, TPEMR, characterizes the repolarization dynamics and show magnitude increases in the BrS patients with respect to controls. This TPEMR increase, measured by TPEMRW2, is also significantly larger in BrS symptomatic patients, associated with a higher SCD risk, than in BrS asymptomatic patients.