Brugada Syndrome Flashcards
What is Brugada Syndrome
A rare inherited heart rhythm disturbance that restricts the flow of sodium ions into the heart cells. As a result, the flow of electrical impulses through the heart is disrupted, which can lead to life-threatening heart rhythms.
Brugada syndrome is a channelopathy, caused by a mutation in the cardiac sodium channel gene: SCN5A.
Restricts sodium influx into myocardial cells (loss of function mutation).
Predisposes patients to developing ventricular arrhythmias and sudden cardiac death.
Autosomal dominant inheritance.
> 50% of cases due to spontaneous mutations.
What does Brugada syndrome increase the risk of?
Supraventricular arrhythmias (20%):
Atrial fibrillation (10-20%).
AVNRT and AVRT.
Slowed atrial conduction and atrial standstill.
Life-threatening ventricular arrhythmias.
Symptoms of brugada
Syncope, dizziness, blackouts, palpitations, SOB and cardiac arrest (approx. 1/3 of patients).
Asymptomatic but routine ECG shows ST segment elevation in leads V1-V3.
Associated atrial fibrillation.
Diagnosis Brugada
Consider family history, symptoms, physical examination and history of ventricular arrhythmia.
12-lead ECG – distinct ST segment elevation in V1-V3.
ECG manifestations can be present continuously but are often dynamic or concealed.
Provocative electrocardiography to unmask characteristic Brugada-type ECG changes.
Electrophysiological study to determine the inducibility of arrhythmias.
Assess ECG for Brugada repolarisation pattern in V1-V3.
In conjunction with one of the following:
Documented VF or polymorphic VT.
A family history of sudden cardiac death at <45 years old and/or coved-type ECGs in family members.
Inducibility of VT with programmed electrical stimulation.
Syncope.
Diagnosis depends on a characteristic ECG findingAND clinical criteria.
What are the three types of BrugS
Type 1 - Coved ST segment - RBBB and coved ST elevation of >2mm in at least one chest lead and a negative T wave: Diagnostic of BrS.
Type 2 - Saddleback - Saddleback appearance with high take-off ST segment of >2 mm & positive/biphasic T wave.
Type 3 - Coved/saddleback STelevation <1mm - less obvious
Types 2 and 3 patterns not diagnostic of BrugS -
Diagnosis is considered when a type 2 or type 3 ST-segment elevation is observed in >1 right precordial lead under baseline conditions and conversion to type 1 pattern occurs after sodium channel blocker administration (ST-segment elevation should be ≥2 mm).
Drug-induced conversion of type 3 to type 2 ST-segment elevation is inconclusive for a diagnosis – warrant further investigation.
What is the Shanghai score?
A score above 3.5 is considered as probable/definite Brugada syndrome.
2-3 points: possible Brugada syndrome.
Below 2 points is considered non-diagnostic.
Why perform high lead ECG positions
Brugada pattern more easily inducible
What is provocation electrocardiography?
A form of this is Ajmaline challenge test for patients:
who are suspected of having Brugada syndrome and
have a normal or inconclusive resting ECG or
they have a first degree relative with confirmed Brugada syndrome.
Asymptomatic or present after a syncopal episode/resuscitated cardiac arrest.
If a person has Brugada syndrome, ajmaline can reveal the characteristic ECG pattern (type-1 Brugada syndrome) that is indicative of the condition - sodium channel blocker -antiarrhythmic
What is ajmaline?
Class 1a antiarrhythmic drug.
Blocks cardiac SCN5A sodium channels.
Prolongation of the cardiac action potential and the accentuation of ST segment elevation.
Intravenous ajmaline administration (1 mg/kg/5 minute period).
Further diminishes Na current already reduced by Brugada mutation so can therefore unmask concealed forms of Brugada.
Ajmaline has a very short half-life and is highly specific for the SCN5A channel.
Ajmaline test diagnostics
A diagnosis is made if RBBB and a characteristic type 1 cove-shaped ST elevation in leads V1-V3 develops on the ECG in response to IV ajmaline administration.
The test should be stopped when any of the following develop:
diagnostic cove-shaped ST elevation,
ventricular ectopic beats,
other arrhythmias,
the QRS widens to ≥130% of the baseline,
the maximum dose of ajmaline is given.
BrS treatment
Low risk, asymptomatic patients: conservative management.
If symptomatic/previous cardiac arrest – ICD for primary or secondary prevention to avoid sudden cardiac death.
Abnormal ECG but asymptomatic – EP study to determine suitability for ICD.
NICE TA314 guidance – “ICDs recommended for treating people with previous serious ventricular arrhythmia who have survived a cardiac arrest due to VT/VF and people with a familial cardiac condition with a high risk of sudden cardiac death, such as Brugada.”
RF ablation of RVOT epicardium effective in suppressing arrhythmogenesis in patients with frequent appropriate ICD shocks.
: Current risk stratification and recommendations for ICD
Flow chart shows the current mode of risk stratification and recommendations for ICD based on conclusions of the 2nd consensus conference and ESC guidelines. If symptomatic (e.g. Cardiac arrest or syncope) and type 1 Brugada ECG pattern, whether it’s spontaneous or induced by class I antiarrhythmic drugs, then it’s suggested that you undergo ICD implantation. If type 1 Brugada ECG pattern and asymptomatic, regardless of whether type 1 ECG pattern is spontaneous or inducible with class I drugs, if EP study shows polymorphic VT or VF is inducible, an ICD is recommended, whereas if not inducible, close follow-up is suggested.
Pharmacological treatments BrS
No pharmacologic therapy proven to reduce the occurrence of ventricular arrhythmias or sudden death.
Quinidine prevents induction of VF and suppresses spontaneous VT/VF – inhibits K+ currents and class 1a AAD.
■ patients with ICD and multiple shocks
■ ICD implantation is contraindicated
■ treatment of supraventricular arrhythmias.
Quinidine increases the AP duration and normalises ECG patterns. Class Ia antiarrhythmic. Blocks calcium-independent transient outward potassium currents.
Fever can induce ECG changes – paracetamol/ibuprofen recommended.
BrS
Avoid all drugs that may induce a type 1 ECG pattern (Na and Ca channel blockers, beta blockers, alcohol).
Fever management. - Fever may induce the characteristic Brugada ECG pattern and has been recognised as a trigger of ventricular arrhythmias in Brugada patients, so should be treated aggressively.
Patients must contact their cardiologist immediately in case of presenting syncope/seizures
Regular follow-ups for early identification of symptoms.
Contact cardiologist immediately in case of new symptoms.
Genetic screening for a mutation in SCN5A gene is strongly recommended in first-degree relatives.
BrS prognosis
Healthy individuals with Brugada-type ECG have a favourable prognosis. Annual death rates <0.5%.
Probst et al. (2010) recruited patients with a characteristic Brugada ECG pattern either at baseline or after drug challenge with previous cardiac arrest, unexplained syncope and those who were asymptomatic.
Cardiac event rates per year: 8% (previous arrest), 2% (syncope) and 0.5% (asymptomatic).
Other studies: asymptomatic patients no greater mortality risk.
Highlights importance of having clear criteria to guide diagnosis and treatment.
