Brugada Syndrome

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

Typical ECG abnormalities in Brugada syndrome

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.

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

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

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.

General features

The diagnosis is based on ECG findings.
It is an inheritable cardiac arrhythmia syndrome with an autosomal dominant inheritance.
Males are often more symptomatic than females, probably by the influence of sex hormones on cardiac arrhythmias and/or ion channels.
The arrhythmias typically occur in patients between 30-40 years of age and often during rest or while sleeping.
The right ventricle is most affected in Brugada syndrome, and particularly (but not specifically) the right ventricular outflow tract.
The prevalence varies between 5-50:10.000, largely depending on the geographic location (especially in some Southeast Asian countries the disease is more prevalent).

Clinical diagnosis

The clinical diagnosis of Brugada syndrome is confirmed in an individual with the following:

Findings
ECG	OMIM	Gene	Protein	Functional role in cardiomyocytes	Effect of mutation
And at least one of the following
And at least one of the following	OMIM: Online Mendelian Inheritance in Man compendium of human genes and genetic phenotypes; BrS1–BrS7: Brugada syndrome types 1–7; NC: no consensus; I_Ca,L: L-type calcium current; I_f: hyperpolarization-activated current; I_K,ATP: ATP-sensitive potassium current; I_Na: fast sodium current; I_to: transient outward potassium current.

Physical examination

Patients can present with symptoms of arrhythmias:

Out-of-hospital-cardiac-arrest
Syncope, pre-syncope (weakness, lightheadedness, dizziness)
Chest pain
Shortness of breath
Paleness
Sweating

Other clinical presentations of Brugada syndrome may include sudden infant death syndrome (SIDS) and sudden unexpected nocturnal death syndrome (SUDS), which is seen in southeast Asia in which young persons die from cardiac arrest with no identifiable cause (also known as bangungut in the Philippines, lai tai in Thailand, pokkuri in Japan and dab tsog in Laos.

However, most patients with Brugada syndrome are asymptomatic and are under medical attention because of family screening for sudden cardiac death/Brugada syndrome or because a Brugada ECG was found coincidentally.

Diagnosis and treatment

Patients who are symptomatic (unexplained syncopes, ventricular tachycardias or aborted sudden cardiac death) may have a symptom recurrence risk of 2 to 10% per year. In these patients an ICD implant is advisable. Further, life-style advice is given (see below).
Some groups advise an electrophysiological investigation (inducibility of ventricular fibrillation) for risk assessment in Brugada patients,[2][3] but others could not reproduce the predictive value of these tests,[4][5] so the value of inducibility is controversial.
In large studies familial sudden death did not appear to be 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 like ajmaline, procainimde or flecainide) life style advice is given. This advice includes:
- A number of medications should not be taken (including sodium channel blockers and certain anti-depressants and anti-arrhythmics, see www.BrugadaDrugs.org)
- Rigorous treatment of fever with paracetamol/Tylenol, as fever may elicit a Brugada ECG and arrhythmias in some patients.
Spontaneous Type I ECGs do appear to be more prevalent in patients who experienced symptoms.

For a full list of the diagnostic criteria, see [6]

Electrocardiographic criteria

Changed lead positions of leads V3 and V5 to increase the sensitiviy to 'catch' a Brugada pattern on the ECG

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

Type I is the only ECG criterion that is diagnostic of Brugada syndrome. The type I ECG is characterized by a J elevation >=2 mm (0.2 mV) a coved type ST segment followed by a negative T wave (see figure). Brugada syndrome is definitively diagnosed when a type 1 ST-segment 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.

The sensitivity of the ECG for Brugada syndrome can be increased with placement of ECG leads in the intercostal space above V1 and V2 (V1ic3 and V2ic3)

Electrocardiograms of Brugada patients can change over time from type I to type II and/or normal ECGs and back. A type III ECG is rather common and is considered a normal variant, but also the Type II is a normal variant (albeit suggestive of Brugada syndrome).

A recent study suggests that fractionation of the QRS complex is a marker of a worse prognosis in Brugada syndrome.[7]

**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