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

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).

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).

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 $\rm V1_{3IC}$).

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.

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.