Brugada Syndrome
Brugada syndrome is a genetic cardiac condition characterized by distinctive ECG abnormalities (coved ST-segment elevation ≥2mm followed by negative T-wave in right precordial leads) and a high risk of sudden cardiac death in individuals with structurally normal hearts. 1
Definition and Epidemiology
- Prevalence is approximately 1:2,000 in the general population 2
- Predominantly affects males in their third to fourth decade of life
- Male gender is a risk factor for sudden cardiac death 1
- Can occur in children and neonates, though less commonly 1
- Primarily inherited in an autosomal dominant pattern 1
Genetic Basis
- Primary mutation occurs in the SCN5A gene (cardiac sodium channel) 1
- Non-SCN5A loci have been reported, but specific genes remain unidentified in many cases 1
- Recent evidence suggests BrS may not be strictly monogenetic, as gene polymorphisms can modify risk 3
- Most cases are not associated with a single causative gene variant, despite being considered an inherited condition 2
Diagnostic Features
ECG Patterns
- Type 1 (diagnostic) pattern: coved ST-segment elevation ≥2mm followed by negative T-wave in leads V1-V3 1
- ECG changes may be dynamic and intermittent, requiring repeated ECGs 1
- "Corrado index": measures ST elevation at J-point (STJ) and 80ms after (ST80), with Type 1 pattern characterized by STJ/ST80 ratio >1 (downsloping ST segment) 1
Diagnostic Assessment
- Examine right precordial leads (V1-V3) for characteristic patterns
- If Type 1 pattern not clear but suspected:
- Confirm correct lead placement
- Repeat ECG if necessary
- Perform high precordial lead ECG (V1 and V2 placed in 2nd or 3rd intercostal space) 1
- Pharmacological challenge with sodium channel blockers can unmask ST segment elevation in concealed forms 1
- Fever can unmask or accentuate the Brugada pattern 1
Risk Stratification
High-risk factors:
- Previous cardiac arrest (increases risk 6-fold) 1
- Spontaneous Type 1 ECG pattern (higher risk than drug-induced pattern) 1
- Previous syncope with spontaneous Type 1 ECG pattern 1, 4
Moderate risk factors:
Management
High-Risk Patients
- Implantable cardioverter-defibrillator (ICD) is the only proven effective therapy for preventing sudden death 1
- Class I indication (strongly recommended) for:
- Survivors of cardiac arrest
- Patients with documented ventricular tachycardia
- Patients with syncope and spontaneous Type 1 ECG pattern 1
Acute Management of Electrical Storm
Preventive Measures
- Aggressive fever management with antipyretics 1, 4
- Avoidance of drugs that may induce or worsen Brugada ECG pattern 1
- Regular cardiac follow-up for all diagnosed patients 1
- Family screening recommended for first-degree relatives 1
Emerging Therapies
- Quinidine may be effective for long-term management in selected patients 4
- Epicardial ablation targeting the arrhythmogenic substrate in the right ventricular outflow tract shows promise 2, 3
Important Clinical Considerations
- ECG findings may be intermittent; repeated ECGs may be necessary 1, 2
- Fever is a significant trigger for life-threatening arrhythmias (27% of events) 4
- ICD implantation carries risk of complications (41% major adverse events reported in pediatric patients) 4
- Asymptomatic patients with spontaneous Type 1 ECG pattern require careful risk assessment 1
- Electrophysiological testing may be considered for risk stratification in asymptomatic patients with spontaneous ST elevation 1
Special Populations
Pediatric Patients
- Spontaneous Type 1 ECG pattern and symptoms at diagnosis are predictors of life-threatening arrhythmias 4
- Management should be age-specific with careful consideration for ICD implantation 4
- Genetic testing may be particularly valuable in pediatric cases 4