Brugada Syndrome

Definition and EtiologyTop

Brugada syndrome (BrS) is a rare autosomal dominant disease that is 8 times more prevalent in men than in women; it is also more frequent in eastern Asia, where it affects 0.05% to 0.1% of the general population. Disease onset is usually between the age of 20 and 40 years but sometimes may occur earlier, particularly in patients with malignant arrhythmias.

Clinical FeaturesTop

Key clinical features include syncope caused by fast polymorphic ventricular tachycardia (VT), cardiac arrest, or sudden cardiac death (SCD). SCD typically occurs at night. Syncope may be a preliminary symptom.

DiagnosisTop

Electrocardiography (ECG) (Figure 1) during sinus rhythm has a distinctive pattern and is characterized by an ST-segment elevation of ≥2 mm with a negative T wave in ≥1 right precordial lead (V1-V3) positioned in the fourth, third, or second intercostal space. This Brugada ECG pattern can be transient and is typically apparent in patients with high fever. Sodium channel blocker antiarrhythmic drugs (flecainide, procainamide, ajmaline) can unmask the pattern.

There are 3 described ECG patterns but only the type 1 morphology is diagnostic of BrS. In case of clinical suspicion of BrS in the absence of a spontaneous type 1 ST-segment elevation, a pharmacologic challenge using a sodium channel blocker is recommended. When a type 1 ST-segment elevation is unmasked using a sodium channel blocker, the diagnosis of BrS should require that the patient also present with 1 of the following: documented ventricular fibrillation (VF) or polymorphic VT, syncope of a probable arrhythmic cause, family history of SCD at <45 years with negative autopsy, coved-type ECG in family members, or nocturnal gasping. The diagnosis of BrS can be challenging.

Differential Diagnosis

Differential diagnosis of right precordial ST-segment elevation includes atypical right bundle branch block, early repolarization, acute myocardial ischemia, arrhythmogenic right ventricular cardiomyopathy, and pectus excavatum.

TreatmentTop

Classification of antiarrhythmic drugs: see Table 1 in Cardiac Arrhythmias.

Antiarrhythmic agents: see Table 2 in Cardiac Arrhythmias.

1. Implantable cardioverter-defibrillator (ICD) is the first-line therapy for patients with BrS presenting with aborted SCD or documented VT or VF. ICDs can be used prophylactically in BrS patients with a spontaneous manifest ECG pattern (type 1) and unexplained syncope with cardiac features.

2. Asymptomatic patients with a Brugada ECG pattern (type 1), either spontaneous or induced by sodium channel blockers, can be closely followed without an ICD after seeking expert advice.

3. Sodium blockers should be avoided; a full list of medications can be found at brugadadrugs.org.

4. Quinidine may be considered, if available, in BrS patients presenting with electrical storm or frequent ICD shocks. It may also be useful in patients who qualify for an ICD but the device is unavailable, refused, or contraindicated. Isoproterenol can be useful in the case of a Brugada VT/VF storm.

FiguresTop

Figure 3.4-1. Electrocardiography (ECG) of a patient with Brugada syndrome: A, nearly undetectable changes; B, a typical ECG pattern 9 days later. Figure courtesy of Dr Andrzej Stanke.