ECG-Based Spatiotemporal Characterization of Delayed and Heterogeneous Ventricular Activation in Brugada Syndrome.

OBJECTIVE: Brugada syndrome (BrS) has been associated with delayed and heterogeneous electrical activation, particularly involving the RVOT. This study proposes a spatiotemporal characterization of ventricular activation using the high-precordial 12-lead electrocardiogram (ECG). METHODS: Delayed ventricular activation was quantified by a lead-dependent propagation progression time (PPT), defined as the time instant within the QRS complex at which 30%, 50%, or 70% of cumulative QRS energy is reached. PPTs were calculated every 30 minutes and characterized temporally, by their 24-hour median and standard deviation, and spatially, by their maximum inter-lead differences. The method was evaluated on 162 subjects (118 patients, 44 controls). RESULTS: BrS patients exhibited significantly longer PPTs across all leads than controls. The largest difference was observed at 70% QRS energy (median PPT in lead $\rm V2_{2IC}$: BrS 74[63;87]ms vs control 60[56;66]ms, p-value< 0.001). Increased spatial dispersion of PPT was observed in male patients (maximum inter-lead difference: male 20[12;26]ms vs female 12[9;20]ms, p-value< 0.01), potentially reflecting sex-related differences in ventricular conduction patterns. The intra-subject temporal variability of PPT at 70% QRS energy can distinguish between controls and BrS patients with induced type-I ECG pattern (AUC>0.75 in leads $\rm V2_{2IC}$ and $\rm V1_{3IC}$). CONCLUSION: PPT analysis captures the spatiotemporal dynamics of delayed and heterogeneous ventricular activation associated with BrS and provides a quantitative non-invasive characterization of conduction abnormalities. SIGNIFICANCE: Developing a non-invasive ECG-based approach for the assessment of ventricular conduction dynamics may complement current non-invasive ECG-based diagnostic tools in BrS, even in patients without spontaneous type-I pattern manifestation.