Brugada Syndrome

What happens in Brugada syndrome

Each heartbeat is triggered by electrical currents moving through ion channels in heart muscle cells. In many people with Brugada syndrome, a variant in the SCN5A gene reduces the sodium current, mainly in the right ventricle's outflow area. This creates an electrical imbalance that can set off polymorphic ventricular tachycardia or ventricular fibrillation, a chaotic rhythm in which the heart quivers instead of pumping. If it stops on its own, the person faints. If it continues, it causes cardiac arrest.

Episodes tend to occur at rest or during sleep, when the vagal (slowing) nervous system dominates, and during fever, which further impairs the faulty sodium channels.

Symptoms

Many people never have symptoms and are found by an ECG or family screening. When symptoms occur:

• fainting (syncope), often without warning, at rest or at night
• palpitations or a racing heartbeat
• nocturnal agonal breathing: gasping or gurgling during sleep
• seizure-like episodes from lack of blood flow to the brain
• sudden cardiac arrest, which may be the first sign

Causes and genetics

Brugada syndrome is usually inherited in an autosomal dominant pattern: each child of an affected parent has a 50% chance of inheriting the variant. SCN5A variants are found in about 20 to 30% of patients; in most, no single gene is identified, and several genes plus other factors contribute. Not everyone with the variant develops the ECG pattern or symptoms.

It is diagnosed more often in men, possibly because of testosterone's effects on heart currents, and is more common in people of Southeast Asian descent. Brugada syndrome is one of several inherited rhythm disorders, alongside long QT syndrome, that cardiologists consider after unexplained fainting.

Triggers

• Fever: a well-known trigger, especially in children.
• Certain medicines: some antiarrhythmics (flecainide, procainamide), some antidepressants and antipsychotics, some anesthetics (such as propofol infusions and local anesthetics like bupivacaine), lithium, and others. Websites such as BrugadaDrugs.org list drugs to avoid.
• Large meals and heavy alcohol use.
• Cocaine and cannabis.
• Low potassium and electrolyte imbalance.

Diagnosis

• ECG: the hallmark type 1 Brugada pattern is a "coved" ST-segment elevation of 2 mm or more followed by a negative T wave in the right chest leads (V1 and V2). Placing these leads one or two rib spaces higher increases detection. The pattern can come and go.
• Drug challenge test: if the pattern is suspected but not visible, a sodium channel blocker (ajmaline, flecainide or procainamide) is given under monitoring in a hospital to unmask it.
• Fever ECG: an ECG during fever may reveal the pattern.
• Genetic testing: confirms a variant in some people and allows targeted family testing.
• Other tests: echocardiogram or cardiac MRI to exclude structural heart disease; heart rhythm monitoring.

A type 1 pattern alone, especially if spontaneous, establishes the diagnosis; type 2 and 3 "saddleback" patterns are suggestive but not diagnostic.

Risk assessment

Highest risk:

• previous cardiac arrest or ventricular arrhythmia
• fainting likely due to arrhythmia
• a spontaneous (not drug-induced) type 1 pattern

Lower risk: no symptoms and a pattern seen only after a drug challenge. Electrophysiology study and risk scores may be used in borderline cases.

Treatment

• Implantable cardioverter-defibrillator (ICD): a device under the skin that detects dangerous rhythms and delivers a shock. It is recommended for people who survived cardiac arrest or had arrhythmic fainting. It does not prevent arrhythmias but treats them.
• Quinidine: an older medicine that reduces arrhythmias, used for people with frequent ICD shocks, those who cannot have an ICD, and arrhythmic storms.
• Catheter ablation: destroying abnormal tissue on the outer surface of the right ventricle can reduce or abolish the Brugada pattern and arrhythmias in selected patients.
• Isoproterenol infusion: in hospital for electrical storms.

Everyday precautions

• Treat fever early with acetaminophen (paracetamol) or ibuprofen, following the label dose.
• Check every new prescription, over-the-counter medicine and anesthetic against the list of drugs to avoid, and carry a medical alert card.
• Avoid binge drinking, very large meals and recreational drugs.
• Keep electrolytes normal during vomiting or diarrhea illnesses.

Family screening

First-degree relatives (parents, siblings, children) should have an ECG, and genetic testing if a variant has been found in the family. Children may need repeat ECGs, especially with fever, because the pattern can appear later.

Outlook

Most people with Brugada syndrome who have no symptoms have a low annual risk of arrhythmic events. With risk assessment, trigger avoidance and an ICD when needed, people with the condition can live normal lives. Exercise is generally allowed after specialist assessment.

Frequently asked questions

What is Brugada syndrome?

Brugada syndrome is an inherited heart rhythm disorder in which faulty sodium channels in the heart can trigger dangerous fast rhythms. It can cause fainting or sudden cardiac death, often during sleep or fever, although many people with the condition never have symptoms.

What are the symptoms of Brugada syndrome?

Many people have no symptoms. When present, symptoms include fainting, palpitations, gasping breathing during sleep, seizure-like episodes and sudden cardiac arrest. Because the first event may be serious, family screening of relatives of affected people is important.

Why is fever dangerous in Brugada syndrome?

High temperature further reduces the function of the faulty sodium channels, which can unmask the Brugada ECG pattern and trigger ventricular arrhythmias. People with Brugada syndrome should treat fevers early with fever-reducing medicine and seek medical advice for high or persistent fever.

Is Brugada syndrome hereditary?

Yes. It is usually inherited in an autosomal dominant pattern, so each child of an affected parent has a 50% chance of inheriting the predisposition. Relatives should have an ECG and, when a family variant is known, genetic testing.

Can you live a normal life with Brugada syndrome?

Most people can. Those without symptoms often need only trigger avoidance and regular review. People at higher risk usually have an ICD, which effectively treats dangerous rhythms. Your cardiologist will advise about sports, medicines and anesthesia.