COMMENTARY

Brugada Syndrome Update: More Common Than Imagined

Amal Mattu, MD

Disclosures

July 31, 2014

Introduction

Those who know me know that I love ECGs. I love reading about them, writing about them, and talking about them. A major reason for this infatuation is that the ECG is arguably the most important test in acute care medicine.

This simple test, which is rapid, low-cost (a piece of paper and ink!) and reproducible and can be done at the bedside in any patient regardless of how sick, can provide life-saving information. This intense interest has led me to develop several lectures as well as an open-access, weekly ECG Case of the Week video that I offer to anyone interested in learning more about ECGs.

Because of this interest and my ECG Website, many physicians in emergency medicine in the United States and abroad send me interesting cases, questions, and quandaries pertaining to ECG. Without a doubt, one of the most common topics on which I receive questions has to do with the Brugada syndrome.

First identified and described in the early 1990s, the Brugada syndrome has become one of the most intriguing topics that emergency physicians and cardiologists have been learning about in ECG over the past 2 decades. In short, the Brugada syndrome is an abnormality in the electrical system of the heart that predisposes patients to develop episodes of ventricular tachycardia and loss of consciousness. The arrhythmia may spontaneously terminate, after which the patient wakes up and presents for evaluation of syncope; or the arrhythmia may degenerate into ventricular fibrillation, resulting in sudden death.

The ECG of these patients in the asymptomatic state often shows a characteristic incomplete or complete right bundle branch block pattern with ST-segment elevation in leads V1-V2 (Figure 1). Definitive testing for Brugada syndrome is done in the electrophysiology laboratory, where, if the diagnosis is confirmed, an implantable cardioverter-defibrillator (ICD) is placed. Without the ICD, mortality from the condition was thought to be as high as 10% per year.[1]

A full review of the topic is beyond of the scope of this brief essay, and any readers who are not familiar with it are referred to any one of the many review articles or videos available via the Internet. However, for those who are familiar with the Brugada syndrome, a review of the most recent literature on this topic is in order. Two recent articles from the electrophysiology literature provide some outstanding updates on diagnosis and risk assessment of these patients.[2,3]

I will offer some background on this syndrome:

The prevailing theory regarding the pathophysiology of Brugada syndrome is that it is a sodium channelopathy caused by a genetic mutation. Most patients, however, do not appear to have a hereditary pattern of the condition.

ST-segment elevation in leads V1-V2 in these patients comes in 2 varieties (Figure 2): a coved-type (straight or convex upward) terminating in an inverted T-wave, and a saddle-type (concave upward). The coved type is far more predictive of arrhythmic events.

In conjunction with the ECG abnormality, one of the following criteria is also necessary to make the diagnosis:

    i. A history of ventricular tachycardia or ventricular fibrillation;

    ii. A family history of sudden cardiac death;

    iii. A family history of the coved-type ECG abnormality;

    iv. Agonal respirations during sleep; or

    v. Inducibility of ventricular tachycardia or ventricular fibrillation during electrophysiologic studies.

The Brugada ECG pattern is more prominent at night, at rest, and after large meals; this also correlates with when the majority of arrhythmias and sudden death episodes occur.

Fever can induce the ECG abnormality as well as arrhythmias.

Most sodium-channel blockers tend to provoke the ECG abnormality. Electrophysiologists typically will use potent sodium-channel blockers in the electrophysiology laboratory as part of the diagnostic testing for the Brugada syndrome.

Brugada syndrome was first identified as a common cause of sudden death in young males of Southeast Asian descent. However, the condition is now well documented in both men and women from many different ethnic groups, and in a large age range of patients.

The average age at diagnosis of Brugada syndrome is about 40 years. This contrasts with other heart diseases associated with sudden death, such as hypertrophic cardiomyopathy and long QT syndrome, which typically occur at younger ages. However, arrhythmic events related to Brugada syndrome are reported in patients ranging from 2 days to 84 years of age. The condition is now believed to be one of the potential causes of sudden infant death syndrome and sudden cardiac death in young children.

Asymptomatic patients with the Brugada pattern on ECG (ie, an incidental finding of the Brugada pattern) and patients with only a drug-induced Brugada pattern appear to have a much lower risk for arrhythmia than previously thought -- perhaps less than 5% over 3-4 years.

Because of the low annual rate of arrhythmic events in asymptomatic patients and the negative physical and psychological effects of ICDs, the need for ICD placement needs to be very carefully evaluated.

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