Brugada syndrome
What is it?
Brugada syndrome (BrS) is a genetic heart disease that carries an increased risk of sudden death.
The disease typically occurs during adulthood, on average around 40 years of age, and is estimated to be responsible for at least 4% of all sudden deaths, among which at least 20% of the deaths are of patients with a structurally normal heart.
Most diagnoses of BrS occur in young adults, often male, following the sudden death of a family member or with the occurrence of symptoms, such as syncope or cardiac arrest. The BrS has a characteristic electrocardiographic framework, represented by a typical over-leveling of the ST segment in the right precordial electrocardiographic leads (from V1 to V3), called Brugada pattern type 1. In cases where the electrocardiographic panel is suspected, but not diagnostic (Brugada pattern type 2 or 3), to confirm or exclude the diagnosis it may be necessary to carry out a test with class I antiarrhythmic drugs (e.g. ajmaline or flecainide), which unmask the diagnostic (type 1) Brugada pattern.
BrS patients generally have a structurally normal heart, although magnetic resonance imaging showed mild structural abnormalities of the right ventricle in a subset of patients.
This disease seems to be linked to a malfunction of one or more ion channels, which are structures that allow the transit of these ions (sodium, potassium, magnesium and calcium) through the cell surface. The first genetic alteration identified in BrS was that of the SCN5A gene that codes for the sodium channel. Subsequently, numerous and further genetic anomalies have been associated with BrS, with more than 300 mutations described.
Which are the symptoms?
Characteristic of the BrS is the extreme variability of the clinical presentation.
Unfortunately, in a considerable percentage of patients, the first clinical manifestation of the disease is sudden death, due to fatal ventricular arrhythmias. The latter catastrophic event underlines the difficulty of managing the disease in predicting which individuals will be at greatest risk, since before this event, the vast majority of patients do not present with any warning symptoms.
Affected patients may also be totally asymptomatic or exhibit symptoms due to cardiac arrhythmias, with episodes of syncope (i.e. loss of consciousness), episodes of palpitations or heart rate. Sometimes patients may have seizures and symptoms that can be confused with epilepsy. Symptoms often occur at rest, in the recovery phase from exercise or during night sleep.
- palpitations
- dyspnea
- fatigue
- syncope
How is it diagnosed?
A timely diagnosis is crucial for this syndrome, as the affected patient may be at risk of potentially fatal arrhythmias. When the suspicion of Brugada syndrome has been raised, family history and the electrocardiographic tracing must be obtained, and other cardiological tests performed, including echocardiogram (to exclude the presence of any heart disease).
Confirmation of a Brugada syndrome diagnosis is possible with the presence of a spontaneous type 1 pattern.
However, in most cases, the ECG pattern is suspicious of BrS, but not diagnostic (type 2 or 3 pattern), and it may be necessary to resort to a pharmacological test with Ajmaline, which in predisposed subjects induces the appearance of the Brugada pattern type 1, and therefore allows to exclude or confirm the diagnosis of Brugada syndrome.
In the case of a positive pharmacological test, an endocavitary electrophysiological study (EES) may be necessary, in order to verify the possible vulnerability of a patient to potentially malignant ventricular arrhythmias.
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How is it treated?
Once the diagnosis of BrS is made, the therapeutic approach depends on the patient’s level of risk. Brugada syndrome does not present with a definite clinical progression, and therefore a patient may experience new clinical elements indicative of a possible change in the level of risk. Therefore, it is appropriate to carry out checks every six months.
Currently the therapeutic options available for Brugada syndrome are essentially of three types:
- Implantation of cardiac defibrillator (ICD, intracavitary or subcutaneous) or implantable cardiac monitors (subcutaneous ICM or loop recorder)
- Transcatheter epicardial ablation of the arrhythmic substrate
- Drug therapy with specific antiarrhythmic drugs (Quinidine)
In our center, we have developed an approach based on the clinical characteristics of each individual, born from our wide and long clinical experience with thousands of cases followed with a long follow-up.
- ICD
ICD is the only therapy with proven efficacy in preventing sudden arrhythmic cardiac death.
The implantation of a defibrillator is necessary in the event of a finding of BrS that presents with high risk characteristics. The risk stratification is based on an evaluation of a series of objective clinical parameters (electrocardiographic, non-invasive, clinical parameters deriving from the electrophysiological study) together with the presence of symptoms attributable to potentially lethal arrhythmias.
Given the possible presence of supraventricular arrhythmias or disturbances of the condition, the use of the intracavitary defibrillator is generally preferred, even if in younger subjects, or in patients who have had problems related to the intracavitary defibrillator you can opt for the implantation of a subcutaneous defibrillator.
An approach that is based on multiple parameters is always necessary in order to optimize the most appropriate therapeutic choices, based on the clinical needs of each individual patient. In fact, each of these choices is based on the assessment of the risk of developing potentially fatal arrhythmias, and this is carried out both in the adult and pediatric population. In the latter context, in the most serious and most risky cases it is possible to implant a defibrillator. Instead, in conditions of apparently lower risk, it is possible to offer the implantation of a cardiac monitor under the skin (implantable cardiac monitor ICM or better known as loop recorder) that constantly records the electrocardiogram. The latter offers the possibility of monitoring patients for many years in order to document any arrhythmias that may change the assessment of the arrhythmic risk over time, and therefore modify the therapeutic strategy if indicated.
Each of these devices, ICD or ICM, are available in association with remote monitoring technology, better known as home monitoring. This technology allows you to monitor the operation of these devices remotely while the patient is at home. A modem connected wirelessly records the information of the implanted device and sends it to a secure website, which is only accessible to doctors. In this way, doctors can check not only the correct functioning of the device, but also the onset of any arrhythmias, so that they can intervene promptly with the most appropriate therapeutic strategies. - EPICARDIAL ABLATION
In 2015, our team led by Prof. Pappone demonstrated that the arrhythmogenic substrate of Brugada syndrome is preferentially located in the epicardial region of the outflow tract and the anterior wall of the right ventricle. These areas are characterized by the presence of abnormal electrical potentials that can give rise to those arrhythmias capable of triggering cardiac arrest in patients with BrS.
Once the epicardial arrhythmogenic substrate has been precisely identified, our team has always shown that epicardial ablation by radio frequency is able to eliminate all electrical anomalies, and this leads to the immediate disappearance of the electrocardiographic pattern of Brugada syndrome and the absence of ventricular arrhythmias in follow-up.
This procedure was proposed and developed in our center, which is the most experienced center in the world for this type of intervention.
A prospective study is currently underway in our center to evaluate the effectiveness and safety of this type of intervention..
Currently more than 600 patients with Brugada syndrome have undergone ablation, with an extremely low incidence of perioperative complications.
The ablation strategy proposed by our group can be applied safely and effectively to a greater number of patients with Brugada syndrome considered at risk.
This experience is the largest case history in the world of patients with BrS treated by ablation, and this establishes the first step for a new strategy for the treatment of BrS available to affected patients.
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