Brugada Syndrome

Symptoms of Brugada syndrome range from the absence of any symptoms to sudden cardiac death. Sudden cardiac death typically occurs during sleep, possibly secondary to increased vagal tone. Approximately 80% of Brugada syndrome patients who develop ventricular tachycardia or ventricular fibrillation experience syncope. Palpitations and dizziness have also been described as possible symptoms. History of a febrile illness may be present as fever may precipitate symptoms and arrhythmias. 10 to 30% of Brugada syndrome patients will have an atrial arrhythmia, and supraventricular tachycardia is also more common in Brugada syndrome patients than the general population. However, 72% of those with Brugada syndrome will not show any symptoms, and 28% will not have a family history of sudden cardiac death.

A 12-lead electrocardiogram is significant to both diagnose and decide management options of Brugada syndrome. Three different ECG patterns have been described in Brugada syndrome patients: coved ST elevations greater than 2 mm accompanied with an inverted T wave (type I), saddleback-shaped ST elevation greater than 2 mm (type II), and saddle-back shaped ST elevations less than 2 mm (type III). Additionally, patients with a normal ECG and high-risk factors may require a drug challenge test to reveal the typical ECG findings of ST elevations in the precordial leads V1 to V3. These high-risk factors that may require provocative drug testings include having a family history of Brugada syndrome, family history of sudden cardiac death, and symptoms consistent with Brugada syndrome in the setting of questionable ECG abnormalities. [3]

Class IA antiarrhythmics (such as procainamide and ajmaline) and IC antiarrhythmics (such as flecainide and propafenone), which act as sodium channel blockers, are the drugs used in the challenge test. Brugada ECG findings may also be revealed after cocaine use or tricyclic antidepressant toxicity. Electrolyte abnormalities, such as hyperkalemia and hypercalcemia have been known to reveal ST elevations in the right precordial leads.[5]

If a drug challenge test is normal in a pediatric patient, it may require repetition after the child reaches puberty, given the hormonal effects on Brugada syndrome phenotype. Another diagnostic test described to expose the ST elevations of Brugada syndrome is the full stomach test, where ECGs are obtained before and after a large meal, which causes an increase in vagal tone. Other tests that may be useful for some patients include genetic testing for SCN5A mutations and invasive electrophysiology. [3]

An implantable cardioverter-defibrillator (ICD) is the mainstay of treatment of Brugada syndrome patients. Current recommendations are to perform ICD placement in those who survived cardiac arrest, patients with Brugada ECG abnormalities and syncope, and those who can have Brugada ECG findings on drug challenge tests. Pharmacological treatment with quinidine is also an option. There are conflicting results about using quinidine instead of ICD placement; however, quinidine is useful in Brugada syndrome patients with an ICD who experience multiple shocks and in those who have contraindications for ICD placement. Finally, radio frequency ablation of the anterior part of the right ventricular outflow tract is a new, emerging therapy with a promising prognosis for Brugada syndrome patients. Treatment of asymptomatic individuals with Brugada syndrome ECG findings is more complicated. Personalized risk-stratification is essential in providing the right management for these asymptomatic patients depending on their risk factors using a multi-disciplinary approach and with close and frequent follow-up. [6]

Many of the conditions that may be mistaken for Brugada syndrome also cause syncope as a common symptom. Standard of care for evaluation of syncope is to obtain a 12-lead ECG to evaluate for many of such diseases that may resemble Brugada syndrome. These diseases include QT prolongation, Wolff-Parkinson-White syndrome, pulmonary embolism, sick sinus syndrome, early repolarization syndrome, electrolyte abnormalities, and atrial fibrillation. [3]

Brugada syndrome is not very common, but because it is associated with sudden death, it is important for healthcare workers to be aware of the ECG presentation. The disorder is best managed by an interprofessional team that includes a cardiologist, electrophysiologist and a genetic counselor. The key to diagnosis is a comprehensive medical history of syncopal attacks, chest discomfort or dizziness. Once the diagnosis is made, patients need to be educated about the potential for cardiac arrest. While an ICD is routinely implanted in these patients, it also predisposes them to device-related complications and inappropriate shocks. The actual incidence of death from Brugada syndrome is not known but may account for 3-20% of all sudden deaths in patients with structurally normal hearts. Sudden deaths tend to occur early after the fourth decade of life. The patient, family, and coworkers must be educated about the basics of CPR. Once the diagnosis of Brugada syndrome is made, genetic counseling should be offered to the family.[7][8] (Level V)