Brugada Syndrome

Author(s)	P.G. Postema, MD
Moderator	P.G. Postema, MD
Supervisor
some notes about authorship

The Brugada syndrome is an hereditary disease that is associated with higher risk of sudden cardiac death. It is characterized by typical ECG abnormalities: ST segment elevation in the precordial leads (V1 - V3).

Dr. Pedro Brugada. Pedro and Josep Brugada described in 1992 a landmark publication with a case-series of 8 patients with sudden cardiac death. [] Currently, three brothers of the Brugada family (Pedro, Josep and Ramon Brugada) conduct research in the syndrome that has been named after them.

Typical ECG abnormalities in Brugada syndrome: ST elevation in V1-V3, without ischemia.

The SCN5a gen is located on the short arm (p) of chromosome 3

Characteristics of the Brugada syndrome:

autosomal dominant inheritance. If one of both parents are affected, their children have a 50% chance of inheriting the disease.
Man are more often symptomatic than women, probably by the influence of sex hormones on cardiac arrhythmias.
The arrhythmias usually occur between 30 and 40 years of age. (range 1-77 yrs) and often during rest or while sleeping.
Only in about 30% of patients, genetic defects can be detected in the (SCN5A) gen. In the other patients the disease is probably multi-genetic or caused by yet unknown genetic defects.
The right ventricular outflow tract (right before the pulmonary valve) is most affected in the Brugada syndrome.
The prevalence varies between 5-50:10.000, largely depending on geographic location. In some south-east Asian countries the disease is endemic and sometimes considered the second cause of death amongst young men (after car accidents). There it is called 'Sudden Unexpected Death Syndrome' (SUDS). In different Asian countries, different names have been given to the syndrome: in the Phillipines it is called bangungut (to rise and moan in sleep) and in Thailand lai tai (death during sleep)

The Brugada brothers were the first to describe the characteristic ECG findings and link them to sudden death. Before that, the characteristic ECG findings, were often mistaken for a right ventricle myocardial infarction and already in 1953, a publication mentions that the ECG findings were not associated with ischemia as people often expected.[2]

Diagnosis and treatment

Patients who are symptomatic (syncope, ventricular tachycardias or survivors of sudden cardiac death) have a mortality risk of up to 10% per year. In these patients an ICD should be implanted.
Some groups advice an electrofysiologic investigation for risk assessment in Brugada patients,[3][4] but others could not reproduce the predicive value of these tests,[5][6] so this is still controversial.
In large studies familiar sudden death is not a risk factor for sudden death in siblings.
In asymptomatic patients in whom the Brugada ECG characteristics are present either spontaneously or provoked by fever or sodium channel blockers (ajmaline, flecainide) life style advices are given, which include:
- A number of medications should not be taken (amongst others beta-blockers, and sodium channel blockers such as certain anti-depressants and anti-arrhythmics)
- Rigorous treatment of fever with paracetamol / Tylenol

For a full list of the diagnostic criteria, see [7]

Electrocardiographic criteria

Three ECG repolarization patterns in the right precordial leads are recognized in the diagnosis of Brugada syndrome.

Type I is the only ECG criterium that is diagnostic of Brugada syndrome. Type I repolarization is characterized by a coved ST-segment elevation >=2 mm (0.2 mV) followed by a negative T wave (see figure). Brugada syndrome is definitively diagnosed when a type 1 ST-segment elevation is observed in >1 right precordial lead (V1 to V3) in the presence or absence of a sodium channel–blocking agent, and in conjunction with one of the following:

documented ventricular fibrillation (VF)
polymorphic ventricular tachycardia (VT)
a family history of sudden cardiac death at <45 years old
coved-type ECGs in family members
inducibility of VT with programmed electrical stimulation
syncope
nocturnal agonal respiration.

Electrocardiograms of Brugada patients can change over time from type I to type II ECGs and back. A type III ECG is rather common and is concidered a normal variant.

**ST segment abnormalities in the different types of Brugada syndrome**[8]
	Type I	Type II	Type III
J wave amplitude	>= 2mm	>= 2mm	>= 2mm
T wave	negative	positive or biphasis	positive
ST-T configuration	coved type	saddleback	saddleback
ST segment (terminal portion)	gradually descending	elevated >= 1mm	elevated < 1mm

Examples of Brugada syndrome type I

Examples of Brugada syndrome type II

External links

Cardiogenetics website of the AMC cardiogentica.nl
Brugada.org
Genereview Brugada

Referenties

All Medline abstracts: PubMed | HubMed