313 BRUGADA SYNDROME MIMICRY: THE IMPORTANCE OF AN EXTENDED FOLLOW-UP
Authors: Dossi Filippo , Bernardelli Alice , Raccis Mario , Maggi Roberto , Brignole Michele , Parodi Guido 
Published: December 2022

Abstract

Introduction
Brugada Syndrome (BrS) is a genetically inherited condition associated with the risk of fatal arrhythmias and sudden cardiac death (SCD) occurring in a structurally normal heart. This disorder was historically related to mutations in the SCN5A gene, but recent observations suggest a more complex genetic inter-play, highlighting the possible overlap with structural cardiomyopathies, including hypertrophic cardiomyopathy (HCM).

Case Presentation
In May 2005, an asymptomatic 56-year-old man with a family history of unexplained SCD was referred to our outpatient clinic. A 12-lead ECG showed a type 2 Brugada pattern whilst transthoracic echocardiogram (TTE) was normal. Ventricular fibrillation (VF) was induced during an elective electrophysiological study and a transvenous implantable cardioverter-defibrillator (ICD) was implanted for primary prevention. More than 10 years later, in March 2022, our patient was admitted to the hospital because of palpitations. The ECG revealed a typical atrial flutter with a high ventricular rate, successfully treated with catheter ablation. Post-procedural ECG showed the persistence of type 2 Brugada pattern in association with new-onset T wave inversion in inferolateral leads and signs of ventricular hypertrophy. TTE revealed asymmetric left ventricular hypertrophy, with left ventricular outflow tract (LVOT) obstruction determined by mitral systolic anterior motion and preserved LV systolic function. The patient was treated with optimal medical therapy with symptom improvement and reduction of LVOT obstruction at a 3-month follow-up TTE.

Discussion
The distinction between Brugada phenocopy and BrS electrocardiogram patterns is not obvious, and according to our experience a Brugada type 2 pattern could be an early ECG marker of a concealed HCM which became manifest over an extended follow-up. Brugada ECG phenocopies are clinical entities characterized by type 1 or type 2 Brugada patterns elicited by an underlying condition, the disappearance of the pattern with the resolution of the condition and the absence of classical symptoms. Several pathogenic variants involving other and different genes have been recently reported suggesting a possible overlap with structural cardiomyopathies. Recently, two other cases of incidental findings of a Brugada ECG pattern in the context of HCM were described. Both patients had a common pathogenetic splicing mutation in the MYBPC3 sarcomeric gene (encoding for the cardiac myosin-binding protein C) responsible for HCM with no genetic mutations associated with Brugada syndrome. This fact suggests that patients are not simultaneously affected by BrS and HCM but a clinically manifest HCM with a specific genetic background can lead to an early BrS electrical manifestation.

Conclusion
Our experience confirms that a Brugada type 2 ECG pattern could be a very early sign of a concealed HCM manifested over 10 years later. The importance of proper risk stratification and regular follow-up has thus crucial implications in patient clinical management. However, whether Brugada pattern associated with structural heart disease is linked to an increased risk of sudden cardiac death is still unknown and needs further investigations.