13th March 2024

Brugada syndrome

Pathophysiology

Brugada syndrome is an autosomal dominant condition, more common in men, presenting in adulthood. It is defined by ECG abnormalities with associated ventricular tachyarrhythmias or sudden cardiac arrest. Individuals with ECG findings who are asymptomatic have Brugada pattern, not syndrome.

Brugada syndrome results from mutations in SCN genes, which code for cardiac sodium channels. These sodium channels result in short cardiac action potentials, predisposing to arrhythmias.

Clinical manifestations

Individuals with Brugada syndrome experience ventricular tachyarrhythmias such as ventricular fibrillation or polymorphic ventricular tachycardia, which can result in syncope or sudden cardiac arrest; the latter is the first presentation in one-third of patients. Affected individuals may also experience nocturnal agonal respiration or palpitations related to atrial fibrillation, which is associated with Brugada syndrome.

ECG abnormalities and cardiac arrest in those with Brugada syndrome are associated with triggering factors, including:

• Fever
• Drugs including sodium channel blockers such as flecainide, beta-blockers, calcium channel blockers, tricyclic antidepressants, alcohol, cocaine
• Electrolyte abnormalities such as hyperkalaemia and hypokalaemia

Diagnostics

For a diagnosis of Brugada syndrome to be made, a patient requires a Brugada pattern on ECG and either symptoms or a family history in keeping with Brugada syndrome. The diagnostic ECG changes are coved ST-segment elevation in one or more of the right precordial leads (V1-3) followed by a negative T wave.

In individuals where Brugada syndrome is suspected but the basal ECG is not diagnostic, ECG abnormalities can be elicited by a drug challenge with a sodium channel blocker such as flecainide.

It is important to exclude other causes for V1-3 ST elevation on ECG, such as ischaemia or pericarditis.

The diagnosis commonly occurs after a patient has a cardiac event and then is found to have ECG abnormalities. Those with Brugada syndrome will require genetic testing.

Management

The first line treatment option for Brugada syndrome is insertion of an implantable cardioverter-defibrillator to stop arrhythmias and prevent cardiac arrest. If someone experiences recurrent ICD shocks due to arrhythmias, then they may require antiarrhythmic medications. 

Those with Brugada syndrome should avoid medications previously mentioned that may result in ECG changes, and should individuals develop a fever, this should be promptly investigated and treated.

Those with the Brugada pattern typically do not require specific treatment.

References

• UpToDate – Brugada syndrome
• European Society of Cardiology – Management of patients with a Brugada ECG pattern – https://www.escardio.org/Journals/E-Journal-of-Cardiology-Practice/Volume-7/Management-of-patients-with-a-Brugada-ECG-pattern