Late potentials assessment - an useful tool for Brugada Syndrome risk stratification

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. INTRODUCTION: Brugada syndrome (BrS) is a channelopathy confining an increased risk of sudden cardiac death (SCD). Asymptomatic patients (pts) management remains challenging enhancing the necessity for additionally stratification tools. PURPOSE: To evaluate the role of the non-invasive assessment of late potentials (LP) based on SA-ECG as stratification tools in a BrS cohort. METHODS: Prospective, observational single-center study of pts with BrS with the following criteria (1) Type 1 Brugada ECG pattern, either spontaneous or drug induced; (2) SA-ECG performed before anti-arrhythmic treatment; (3) minimum follow up duration of 12 months. LPs were evaluated by SA-ECG with determination of the total filtered QRS duration (fQRS); root mean square voltage of the 40ms terminal portion of the QRS (RMS40) and duration of the low amplitude electric potential component of the terminal portion of the QRS (LAS40) in conventional and modified right precordial leads. Malignant arrhythmic events (MAEs) were defined as a composite event of SCD or appropriate ICD shocks. Association of relevant risk factors and MAE was conducted with Univariate Cox regression analysis, as well as SA-ECG evaluated as a continuous and categorical divided on standard cut-offs (fQRS >114ms, RMS40<20µV, LAS40>38ms). A risk score for predicting MAE was computed incorporating the significant LPs variables. RESULTS: A total of 106 pts fulfilled the inclusion criteria (mean age: 48 ± 12 years, 67.9% male), 52 (49.1%) with type 1 spontaneous pattern. The majority were asymptomatic at baseline (81.1%) while 13 presented with syncope and 3 with polymorphic VT/cardiac arrest. A total of 10 (7.1%) pts MAEs were documented during a mean 4.7 years - 4 with SCD and 6 with appropriate ICD shocks. Clinical presentation with a polymorphic VT/cardiac arrest (p <0.001) and LP evaluated on SA-ECG were significant predictors of MAE on univariate analysis, except for RMS40 on conventional leads. Neither of the common risk factors (male gender, spontaneous type 1 pattern at baseline, previous syncope or the presence of a pathogenic SCN5A mutation) were predictors of MAE during follow-up– figure 1. Positive LPs defined by standard cut-offs, in all variables and leads, were significantly associated with an increased risk of MAE during follow-up – figure 2. A LP score was computed incorporating the standard cut-offs on conventional leads. The presence of 2 and 3 positive LP represented an additionally 4.7-fold increased risk of MAE during follow-up (HR 4.693, 95% CI 1.506-14.624, p = 0.008) – figure 2. CONCLUSION: LPs based on noninvasive assessment SAECG represent an useful prognostic stratification tool in BrS. A LP score based on standard cut-offs identified a subset of pts at a higher risk of events and who may deserve individualized preventive strategies.