Brugada Syndrome

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Brugada syndrome

• Brugada syndrome is a rare but potentially life-threatening inherited disease that predisposes patients to fatal cardiac arrhythmias. 
  
• The syndrome is characterized by the ECG findings of a right bundle branch block and ST-segment elevations in the right precordial leads (V1 to V3). 
  
• Genetically, Brugada syndrome is primarily linked to mutations in the SCN5A gene, accounting for 15 to 30% of cases. 
  
• However, its inheritance follows an autosomal dominant pattern with variable expressivity and reduced penetrance. 
  
• Environmental factors, such as temperature, certain medications, electrolyte imbalances, and cocaine use, can influence its presentation.
  
• The prevalence of Brugada Syndrome is approximately 3 to 5 per 10,000 people. Brugada syndrome is approximately 8 to 10 times more common in males than females. 
  
• Brugada syndrome is also more prevalent in those who are of Southeast Asian descent. 
  
• The mean affected age is 41 years old. 
  
• Brugada syndrome accounts for 4% of all sudden cardiac deaths.
  

Clinical manifestations

• Symptoms of Brugada syndrome vary widely, with many individuals remaining asymptomatic. 
• Those who do experience symptoms might encounter blackouts, seizures, palpitations, chest discomfort, breathlessness, or dizziness. 
• Sudden cardiac death, often during sleep, is a potential outcome.
• Brugada syndrome is usually diagnosed between 22 and 65 years of age It is rarely diagnosed in children.
• Interestingly, symptoms might emerge due to triggers like high temperatures, alcohol intake, or dehydration.

Diagnostic Tools of Brugada Syndrome

• The primary diagnostic tool is an ECG conducted in a hospital setting. 
• The use of high-lead positions is thought to increase the diagnostic yield by upto 1.5 times compared with standard lead positions.
• When ECG findings remain equivocal or when spontaneous type 2 or type 3 Brugada pattern is observed, a drug challenge using sodium channel blockers is performed to evoke the type 1 Brugada ECG pattern. 
• Additionally, genetic testing for causative mutations should be considered in specific scenarios.

ECG Patterns of Brugada Syndrome

• Three ECG pattern types were described in patients with Brugada syndrome, although only type 1 changes are considered diagnostic.
• A type 1 Brugada ECG consists of coved ST-segment elevation greater than or equal to 2 mm with a negative T-wave in the right precordial leads, which are thought to be representative of pathophysiological changes in the RVOT.
• Type 1 pattern consists of coved ST-segment elevation with T-wave inversion. 
• Type 2 and type 3 patterns consist of saddleback ST-segment configuration with variable levels of ST-segment elevation.
• The ST-segment elevation is greater than 1mm in type 2 and less than 1 mm in type 3.
• Pragmatically, only a type 1 pattern is diagnostic for Brugada syndrome, whereas patients with type 2 and type 3 patterns should undergo sodium channel blocker provocation testing.
• Type 1 pattern consists of coved ST-segment elevation with T-wave inversion. 
• Type 2 and type 3 patterns consist of saddleback ST-segment configuration with variable levels of ST-segment elevation.
• The ST-segment elevation is greater than 1mm in type 2 and less than 1 mm in type 3.

Diagnosis of Brugada Syndrome
Brugada syndrome is diagnosed when type 1 Brugada ECG pattern is associated with one of the following clinical criteria: 

• Documented VF or polymorphic VT,
  
• Family history of sudden cardiac death at  age younger than 45,
  
• Coved-type ECGs in family members,
  
• Inducibility of VT with programmed electrical stimulation,
  
• Syncope.
  
• Nocturnal agonal respiration.

Treatment of Brugada Syndrome

• Unfortunately, there's no definitive cure for Brugada syndrome, but management options exist. 
  
• For high-risk cases, implantable cardioverter-defibrillators (ICDs) serve as a crucial intervention. 
  
• Additionally, pharmacological treatments like quinidine or novel therapies like radiofrequency ablation offer promise, although their efficacy might vary.
• Note that, the only proven therapy is an implantable cardioverter-defibrillator (ICD). 
• Quinidine has been proposed as an alternative in settings where ICD’s are unavailable or where they would be inappropriate (for example, neonates).
• High temperature, excessive alcohol consumption, and specific medications, can exacerbate symptoms. 
  
• Lifestyle modifications is important in Brugada syndrome to avoid triggers that provoke the condition. 

Conclusion

• In summary, the pathophysiology of Brugada syndrome involves a mutation in cardiac sodium channels. 
  
• Typical ECG shows a pseudo-RBBB and ST elevations in leads V1 and V2. It is more prevalent in Asian males. 
  
• Treatment includes an implantable cardioverter-defibrillator to prevent sudden cardiac death. 
  
• Brugada syndrome is inherited in an autosomal dominant manner.

• Brugada syndrome, though rare, demands careful management. 
  
• Personalized risk assessment, a multi-disciplinary approach, and regular follow-ups are pivotal. 
  
• ​While there's no cure, tailored interventions significantly reduce severe risks associated with this condition.