Most Common Dysrhythmia in Brugada Syndrome
The most common dysrhythmia resulting from Brugada syndrome is ventricular fibrillation (VF), which is the primary cause of sudden cardiac arrest and sudden cardiac death in this condition. 1
Primary Arrhythmic Manifestation
The 2017 AHA/ACC/HRS guidelines explicitly state that Brugada syndrome is "associated with syncope or SCA due to VF, predominantly in young males" 1. This ventricular fibrillation represents the lethal arrhythmia that defines the clinical significance of this channelopathy and drives the need for ICD implantation in symptomatic patients to reduce mortality 1.
Secondary Arrhythmic Manifestations
While VF is the hallmark and most clinically significant arrhythmia, atrial fibrillation is notably common as a secondary arrhythmia in Brugada syndrome, with reported incidences ranging from 6% to 38% 2. This is substantially higher than the general population and represents an important clinical consideration for several reasons:
- Atrial fibrillation is the most common atrial arrhythmia found in Brugada syndrome 2
- AF episodes can trigger inappropriate ICD shocks in patients with implanted devices 2
- The presence of AF may reflect the same underlying channelopathy affecting both atrial and ventricular tissue 2, 3
- Studies show that up to 30% of patients with Brugada syndrome may experience paroxysmal atrial fibrillation in addition to ventricular arrhythmias 3
Clinical Context and Timing
The arrhythmic events in Brugada syndrome demonstrate characteristic patterns:
- 93% of arrhythmic events occur at night or early morning 3
- Events correlate with pronounced ST-segment elevation 3
- This timing suggests vagotonic influence on arrhythmogenesis
Rare Presentation: Monomorphic Ventricular Tachycardia
Recent evidence indicates that monomorphic ventricular tachycardia (MVT) is rarely reported in Brugada syndrome 4. When MVT does occur, it presents with distinct characteristics compared to VF:
- Later age of onset (median 47.7 vs 40.7 years) 4
- Associated with broader epicardial substrate abnormalities 4
- Later recurrences after ICD implantation 4
- Different initiation patterns (more rapid baseline rhythms, less ectopy) 4
Clinical Implications
Understanding that VF is the primary lethal arrhythmia while AF represents a common secondary manifestation is critical for:
- Device programming: Dual-chamber ICDs or careful single-chamber programming is recommended to avoid inappropriate shocks from atrial arrhythmias 2
- Risk stratification: Syncope should be carefully evaluated to distinguish arrhythmic (VF-related) from reflex mechanisms 5
- Treatment planning: Quinidine has demonstrated efficacy in preventing both ventricular and supraventricular arrhythmias 6
The substrate responsible for VF in Brugada syndrome—involving sodium channel dysfunction and prominent transient outward current—likely contributes to arrhythmogenesis in both ventricles and atria 2.