Ventricular Arrhythmia in Brugada Syndrome
Brugada syndrome typically causes polymorphic ventricular tachycardia (VT) and ventricular fibrillation (VF), with VF being the most common life-threatening arrhythmia leading to sudden cardiac death. 1
Primary Arrhythmic Manifestations
Ventricular Fibrillation - The Predominant Arrhythmia
- VF is the hallmark arrhythmia in Brugada syndrome, occurring predominantly in the third and fourth decades of life, though presentation with cardiac arrest can occur in neonates or children 1
- The syndrome is characterized by ST-segment elevation across right precordial leads (V1-V3) in association with a high risk of sudden cardiac death from VF 1
- Patients have structurally normal hearts with a primary sodium channelopathy (SCN5A gene mutation), transmitted in an autosomal dominant pattern with >90% male predominance 1
Polymorphic Ventricular Tachycardia
- Polymorphic VT is the second most common arrhythmia, often degenerating into VF 1, 2
- These rapid polymorphic rhythms can be triggered by fever, vagal tone increases, psychotropic medications, anesthetic agents, cocaine, or excessive alcohol intake 1
- The 2017 AHA/ACC/HRS guidelines specifically recommend intensification of therapy with quinidine or catheter ablation for patients experiencing recurrent ICD shocks for polymorphic VT 1
Monomorphic Ventricular Tachycardia - An Atypical Presentation
While much less common, monomorphic VT can occur in Brugada syndrome but represents an atypical presentation:
- Sustained monomorphic VT is rarely reported in Brugada syndrome 3, 4, 5
- When MVT does occur, patients tend to be older at first event (47.7 vs 40.7 years for VF), have higher QRS duration, and show later recurrences after ICD implantation (median 51 vs 20 months) 3
- MVT in Brugada syndrome is associated with broader abnormal epicardial substrate (11.3 cm² vs 6.8 cm² for VF) 3
- Rapid rhythms >100 bpm are more frequent before MVT than VF (48.1% vs 8.5%), with lower incidence of ectopy (22.2% vs 61.7%) 3
Clinical Risk Stratification Based on Arrhythmia Type
High-Risk Features
- Spontaneous type 1 Brugada ECG pattern with cardiac arrest or sustained VA warrants ICD implantation 1
- Patients with syncope and spontaneous type 1 ECG pattern have a 6-fold higher risk of cardiac arrest compared to asymptomatic patients 1
- Annual incidence of arrhythmic events: 13.5% per year in cardiac arrest survivors, 3.2% per year with syncope, 1% per year in asymptomatic patients 6
Lower-Risk Presentations
- Asymptomatic patients with only drug-induced type 1 pattern have significantly lower risk than those with spontaneous patterns 1
- Observation without therapy is recommended for asymptomatic patients with only inducible type 1 Brugada pattern 1
Important Clinical Pitfalls
Fever is a critical trigger that can acutely predispose to cardiac arrest and must be treated aggressively with antipyretics 1, 6
The ECG pattern can be intermittent and dynamic, potentially normalizing completely over time, so a single normal ECG does not exclude the diagnosis 1, 6
First-degree relatives should undergo screening, as family members may be affected even without a positive family history of sudden death 1