What You Should Know About Brugada Syndrome

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Brugada syndrome is an uncommon, inherited abnormality of the heart's electrical system that can lead to ventricular fibrillation and sudden death in apparently healthy young people. In contrast to most other conditions that cause sudden death in young people, the arrhythmias produced by Brugada syndrome usually occur during sleep, and not during exercise.

Most people diagnosed with Brugada syndrome are young to middle-aged adults, whose average age at the time of diagnosis is 41.

Brugada syndrome is seen much more often in men than in women—in some studies the prevalence in men is nine times higher than in women. In the United States, Brugada syndrome is thought to occur in approximately one in 10,000 people. However, it is more prevalent—possibly as high as one in 100—in people of Southeast Asian descent. The only cardiac abnormality is an electrical one; the hearts of people with Brugada syndrome are structurally normal.

What Are the Symptoms of Brugada Syndrome?

The most devastating problem caused by Brugada syndrome is sudden death during sleep. However, people with Brugada syndrome may experience episodes of lightheadedness, dizziness, or syncope (loss of consciousness) prior to the fatal event. If these non-fatal episodes bring them to a doctor’s attention, a diagnosis can be made and treatment instituted to prevent subsequent sudden death.

Brugada syndrome has been identified as the cause of mysterious “sudden unexplained nocturnal sudden death syndrome,” or SUNDS.

SUNDS was first described several decades ago as a condition affecting young males in Southeast Asia. It has since been recognized that these young Asian men have Brugada syndrome, which is far more prevalent in that part of the world than in most other places.

What Causes Brugada Syndrome?

Brugada syndrome appears to be due to one or more genetic abnormalities that affect the cardiac cells, in particular, in the genes that control the sodium channel.

It is inherited as an autosomal dominant trait, but not everyone who has the abnormal gene or genes is affected in the same way.

The electrical signal that controls the heart rhythm is generated by channels in the cardiac cell membranes, that allow charged particles (called ions) to flow back and forth across the membrane. The flow of ions through these channels produces the heart's electrical signal. One of the most important channels is the sodium channel, which allows sodium to enter cardiac cells. In Brugada syndrome, the sodium channel is partially blocked, so that the electrical signal generated by the heart is altered. This alteration leads to an electrical instability that, under some circumstances, can produce ventricular fibrillation.

In addition, people with Brugada syndrome may have a form of dysautonomia—an imbalance between sympathetic and parasympathetic tone. It is postulated that the normal increase in parasympathetic tone that occurs during sleep may be exaggerated in people with Brugada syndrome, and that this strong parasympathtic tone may trigger the abnormal channels to become unstable, and produce sudden death.

Other factors that can trigger a fatal arrhythmia in people with Brugada syndrome include fever, cocaine use, and the use of various medications, especially certain antidepressant drugs.

Diagnosing and Evaluating Brugada Syndrome

The electrical abnormality caused by Brugada syndrome can produce a characteristic pattern on the ECG, a pattern called the Brugada pattern. This pattern consists of a pseudo-right bundle branch block, accompanied by elevations of the ST segments in leads V1 and V2.

Not everyone with Brugada syndrome has a “typical” Brugada pattern on their ECG, though they very likely will have other subtle suggestive changes. So, if Brugada syndrome is suspected (because, for instance, syncope has occurred or a family member has died suddenly in their sleep), any ECG abnormalities should be referred to an electrophysiology expert, to evaluate whether an “atypical” Brugada pattern may be present.

If a person’s ECG displays the Brugada pattern, and if he or she has also had episodes of unexplained severe dizziness or syncope, has survived a cardiac arrest, or has a family history of sudden death below the age of 45, the risk of sudden death is high. However, if the Brugada pattern is present and none of these other risk factors has occurred, the risk of sudden death appears much lower.

People with Brugada syndrome who have a high risk of sudden death should be treated aggressively. But in those who have the Brudada pattern on their ECG but no other risk factors, deciding how aggressive to be is not nearly as clear-cut.

Electrophysiologic testing has been used to help with this more difficult treatment decision, by clarifying an individual's risk of sudden death. The ability of electrophysiologic testing to accurately assess that risk is far less than perfect. Still, the major professional societies currently support performing this test in people who have the Brugada pattern on their ECGs without additional risk factors.

Genetic testing can help to confirm the diagnosis of Brugada syndrome, but is usually not helpful in estimating a patient's risk of sudden death. Furthermore, genetic testing in Brugada syndrome is quite complex, and often does not yield clear-cut answers. So most experts do not recommend routine genetic testing in people with this condition.

Because Brugada syndrome is a genetic disorder that is often inherited, current recommendations call for screening all first-degree relatives of anyone who is diagnosed with this condition. Screening should consist of examining an ECG, and taking a careful medical history looking for episodes of syncope or severe lightheadedness.

How Is Brugada Syndrome Treated?

The only proven method of preventing sudden death in Brugada syndrome is inserting an implantable defibrillator. In general, antiarrhythmic drugs should be avoided. Because of the way these drugs work on the channels in the cardiac cell membranes, they not only fail to reduce the risk of ventricular fibrillation in Brugada syndrome, but also may actually increase that risk.

Whether someone with Brugada syndrome should receive an implantable defibrillator depends on whether their risk of sudden death is finally judged to be high or low. If the risk is high (based on symptoms or electrophysiologic testing), a defibrillator should be recommended. But implantable defibrillators are expensive and carry their own complications, so if the risk of sudden death is judged to be low, these devices are not currently recommended.

Exercise Recommendations With Brugada Syndrome

Any time a young person is diagnosed with a cardiac condition that can produce sudden death, the question of whether it is safe to perform exercise must be asked. This is because most arrhythmias that produce sudden death in young people are more likely to occur during exertion.

In Brugada syndrome, in contrast, fatal arrhythmias are much more likely to occur during sleep than during exercise. Still, it is assumed (with little or no objective evidence) that strenuous exertion may pose a higher-than-normal risk in people with this condition. For this reason Brugada syndrome is included in the formal guidelines generated by expert panels which have addressed exercise recommendations in young athletes with cardiac conditions.

Initially, guidelines regarding exercise with Brugada syndrome were quite restrictive. The 2005 36th Bethesda Conference on Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities recommended that people with Brugada syndrome avoid high-intensity exercise altogether.

However, this absolute restriction has subsequently been recognized as being too severe. In view of the fact that the arrhythmias seen with Brugada syndrome typically do not occur during exercise, these recommendations were liberalized in 2015 under new guidelines from the American Heart Association and the American College of Cardiology.

According to the more recent, 2015 recommendations, if young athletes with Brugada syndrome have had no symptoms associated with exercise, it is reasonable for them to participate in competitive sports if:

  • They, their physicians, and parents or guardians understand the potential risks involved, and have agreed to take necessary precautions.
  • An automatic external defibrillator (AED) is a normal part of their personal sports equipment.
  • Team officials are able and willing to use the AED and perform CPR if necessary.

Summary

Brugada syndrome is an uncommon genetic condition that causes sudden death, usually during sleep, in otherwise healthy young people. The trick is to diagnose this condition before an irreversible event occurs. This requires doctors to be alert—especially in anyone who has had syncope or unexplained episodes of lightheadedness—to the subtle ECG findings that are seen in Brugada syndrome.

People who are diagnosed with Brugada syndrome can almost always avoid a fatal outcome with appropriate treatment, and they can expect to live very normal lives.

Sources:

Brugada P, Brugada J. Right Bundle Branch Block, Persistent ST Segment Elevation and Sudden Cardiac Death: a Distinct Clinical and Electrocardiographic Syndrome. A Multicenter Report. J Am Coll Cardiol 1992; 20:1391.

Maron BJ, Zipes DP, Kovacs RJ, et al. Eligibility and Disqualification Recommendations for Competitive Athletes with Cardiovascular Abnormalities. Circulation 2015; DOI:10.1161/CIR.0000000000000236.

Priori SG, Wilde AA, Horie M, et al. HRS/EHRA/APHRS Expert Consensus Statement on the Diagnosis and Management of Patients with Inherited Primary Arrhythmia Syndromes: Document Endorsed by HRS, EHRA, and APHRS in May 2013 and by ACCF, AHA, PACES, and AEPC in June 2013. Heart Rhythm 2013; 10:1932.

Zipes, DP, Ackerman, MJ, Estes NA, 3rd, et al. Task Force 7: Arrhythmias. J Am Coll Cardiol 2005; 45:1354.

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