Age and genetics are associated with ventricular fibrillation but not with monomorphic ventricular tachycardia in Brugada syndrome
Authors: Pannone L , Osei R , Gauthey A , Sorgente A , Della Rocca D G , Overeinder I , Bala G , Almorad A , Stroker E , Sieira J , La Meir M , Brugada P , Chierchia G B , Van Dooren S , De Asmundis C 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background/introduction
Brugada syndrome (BrS) is associated with ventricular arrhythmias (VA) in macroscopically normal hearts. VA in BrS can be classified as ventricular fibrillation (VF) and monomorphic ventricular tachycardia (MVT). Although BrS has been initially described in association with VF, MVT is not rare, as it occurs in ≈30% of BrS patients.

Purpose
The aim of this study is to correlate VF or MVT with the genetic background and other clinical variables.

Methods
All BrS patients, were prospectively enrolled in a monocentric registry between 1992 and 2022. Inclusion criteria for the study were: 1) BrS diagnosis; 2) Genetic analysis performed for SCN5A; 3) Classification of variants following ACMG guidelines. Patients with a pathogenic/likely pathogenic (P/LP) variant in SCN5A were defined as (P+). Patients without a P/LP variant were defined as (P-). Primary endpoint was VA occurrence, defined as: documented arrhythmic SCD, documented arrhythmic aborted SCD, VF, sustained MVT or appropriate ICD intervention. All VA events were adjudicated as VF or MVT.

Results
A total of 500 BrS patients were analyzed. A P/LP variant in SCN5A was found in 104 patients (20.8%). After a mean follow-up of 110.9 months, 48 patients (9.6%) experienced a VA, adjudicated as MVT in 18 patients (37.5%) and VF in 30 patients (62.5%).
At survival analysis, P- patients had higher VF free survival, compared with P+ patients (96.5% vs 84.6%, Log-Rank p&lt;0.001) with no difference in MVT free survival (Log-Rank p=0.61), Figure 1. BrS patients &gt; 30 years at diagnosis had higher VF free survival, compared with patients ≤ 30 years at diagnosis (95.5% vs 90.3%, Log-Rank p=0.041), with no difference in MVT free survival (Log-Rank p=0.9), Figure 2. Patients &gt; 50 years at index event had higher VF free survival, compared with patients ≤ 50 years at index event (Log-Rank p=0.002), with no significant difference in MVT free survival (Log-Rank p=0.81).
At Cox multivariate analysis independent predictors of VF occurrence were as follows: Age at index event ≤ 50 years (HR=2.57, CI 95% 1.01-6.6, p=0.04), P/LP variant in SCN5A (HR= 2.35, CI 95% 1.12-4.92, p=0.02), SND (HR= 2.67, CI 95% 1.01-7.04, p=0.044), history of syncope (HR= 2.14, CI 95% 1.02-4.51, p=0.047) and history of aborted SCD (HR= 18.66, CI 95% 8.87-39.27, p&lt;0.001). Independent predictors of MVT occurrence were the following: history of syncope (HR= 2.71, CI 95% 1.26-5.80, p=0.01), history of aborted SCD (HR= 4.82, CI 95% 2.14-10.85, p&lt;0.001), VA inducibility at EPS (HR= 3.71, CI 95% 1.66-8.31, p=0.001).

Conclusion
In a large BrS cohort undergoing genetic analysis MVT occurred in 37.5% of patients and VF in 62.5% of patients. P/LP SCN5A carriers and younger BrS population had a higher incidence of VF with no difference in MVT incidence.