Brugada syndrome is a rare, inherited cardiac channelopathy characterised by an increased risk of ventricular arrhythmias and sudden cardiac death (SCD) 1,2. It is primarily an electrical disorder of the heart, often occurring in the absence of structural heart disease. The hallmark feature is a specific pattern on the 12-lead electrocardiogram (ECG), typically involving ST-segment elevation in the right precordial leads (V1-V3) 1,2.
Epidemiology
Brugada syndrome is relatively uncommon, with prevalence estimates varying geographically, ranging from 5 to 20 per 10,000 individuals 1. It is considered endemic in Southeast Asian countries. The condition typically presents in the third or fourth decade of life, although it can manifest earlier or later. While inherited in an autosomal dominant pattern, there is a marked male predominance, with males affected approximately 5-10 times more frequently than females 1.
Aetiology
Primary causes / triggers: Brugada syndrome is primarily caused by genetic mutations affecting cardiac ion channels, most commonly the cardiac sodium channel gene SCN5A 1,2. These mutations impair the function of the sodium current (INa), leading to abnormal repolarisation and electrophysiological instability. Secondary factors, such as fever, certain medications (e.g., sodium channel blockers, some antiarrhythmics, antidepressants), electrolyte imbalances (e.g., hyperkalaemia), and autonomic influences, can unmask or exacerbate the ECG abnormalities and increase arrhythmic risk 1,2.
Secondary associations: While primarily genetic, the ECG pattern can sometimes be observed transiently in individuals without a genetic predisposition due to the secondary factors mentioned above. However, true Brugada syndrome is an inherited condition 1.
Pathophysiology
The underlying pathophysiology involves dysfunction of cardiac ion channels, particularly the sodium channel, leading to abnormal action potential recovery and repolarisation 1,2. This results in a shortened action potential duration and a prominent epicardial repolarisation abnormality. The ECG manifestation reflects this electrical instability. Three main ECG patterns are described: Type 1 (coved ST elevation ≥2 mm in V1-V3), Type 2 (saddleback ST elevation ≥2 mm J-point elevation and ≥1 mm ST elevation), and Type 3 (similar to Type 2 but with ST elevation <1 mm). Type 1 is considered the most specific for increased SCD risk 1,2.
Clinical presentation
Presenting symptoms: Many individuals with Brugada syndrome are asymptomatic and diagnosed incidentally or during family screening 1. Symptomatic presentation typically occurs in adulthood (often 3rd-4th decade) and includes syncope (often exertional or occurring during sleep) and, most tragically, sudden cardiac death (SCD) 1. Palpitations may also occur. The risk of arrhythmic events is significantly higher in patients presenting with syncope compared to asymptomatic individuals 1.
Physical examination signs: Physical examination is usually unremarkable in the absence of structural heart disease. There are no specific physical signs diagnostic of Brugada syndrome itself. Examination focuses on excluding underlying structural heart disease or conditions that might mimic the ECG findings or trigger arrhythmias 1,2.
Investigations
Bedside & Laboratory
Specific test name: The cornerstone of diagnosis is the 12-lead ECG. Characteristic findings include ST-segment elevation in leads V1-V3, described as either coved (Type 1) or saddleback (Type 2/3) morphology 1,2. Provocative testing with sodium channel blocking agents (e.g., ajmaline, flecainide, procainamide) may be used if the ECG pattern is not evident at rest, but Type 1 pattern is diagnostic even without provocation 1,2. Genetic testing for SCN5A and other associated genes can confirm the diagnosis in some cases, but a negative test does not exclude it (yield ~20%) 1,2. Exclusion of structural heart disease via echocardiography is essential 1,2.
Imaging & Special Investigations
Specific modality / diagnostic study: Echocardiography is crucial to rule out structural heart disease, which can cause similar ECG changes (e.g., ARVC, hypertrophic cardiomyopathy) 1,2. Cardiac MRI may be considered in specific cases. Electrophysiological studies (EPS) are generally not required for diagnosis but may be used in selected cases for risk stratification or ablation therapy 1,2.
Management
Acute / first-line management: Management is primarily focused on risk stratification and prevention of SCD. For symptomatic patients (syncope) or those with a Type 1 ECG pattern, the primary intervention is implantable cardioverter-defibrillator (ICD) implantation 1,2. Avoidance of triggering medications (e.g., Class IC antiarrhythmics, certain psychotropics) and correction of electrolyte imbalances are important 1,2. There is no specific pharmacological therapy to prevent arrhythmias in Brugada syndrome, although quinidine has shown some efficacy in reducing arrhythmic events in certain subgroups 1,2.
Definitive / long-term management: ICD implantation is the mainstay of treatment for high-risk patients. Regular follow-up is necessary. Family screening (ECG and potentially genetic testing) is recommended for first-degree relatives 1,2. Lifestyle modifications, such as avoiding strenuous exercise, may be advised, although evidence is limited 1,2.
Differential diagnosis
Coronary artery disease: Can cause ST elevation, but typically associated with reciprocal ST depression, Q waves, and often chest pain. ECG changes are usually localised to specific leads reflecting the area of ischaemia/infarction, unlike the V1-V3 pattern in Brugada syndrome.
Pulmonary embolism: Can cause right heart strain patterns on ECG, including ST elevation in V1-V3, T wave inversion in inferior leads, and S1Q3T3 pattern. Clinical presentation (dyspnoea, chest pain, tachycardia) and other investigations (CTPA) are key differentiators.
Arrhythmogenic right ventricular cardiomyopathy (ARVC): Can present with ventricular arrhythmias and SCD. ECG may show T wave inversion in V1-V3, epsilon waves, and prolonged QRS duration. Echocardiography and cardiac MRI are crucial for diagnosis, revealing structural abnormalities of the right ventricle.
Prognosis & complications
The primary complication is SCD, particularly in symptomatic patients or those with a Type 1 ECG pattern. The prognosis is significantly improved with ICD implantation, which effectively prevents SCD in high-risk individuals 1,2. The natural history varies, with some individuals remaining asymptomatic throughout life, while others experience recurrent syncope or SCD 1,2.
