Brugada Syndrome
ECG – ST elevation V1,2,3 with RBBB.
- autosomal dominant, most common gene SCN5A (20%) which encodes the Na+ channel
- fibrotic changes are common, esp RV outflow tract
- more in males, Asian
- onset of symptoms – adulthood. Often after fever, after heavy meal, Xs alcohol
- drugs which might exacerbate – flecainide, verapamil, propanolol, amitryptiline, alcohol, cocaine
- most common rhythms – VF, polymorphic VT, AV re-entrant tachy
- the most accepted theory to explain the ECG changes and the arrhythmogenic basis is based on the effect of the decrease of the inward positive currents (Na+, Ca+2) on the potassium transient outward current, whose expression levels vary across the myocardium layers (epicardium>endocardium)
- A family history of sudden death does not translate into increased risk in relatives
3 forms. Only Type 1 ECG changes can confirm Dx of Brugada (T2,3 signs often seen in patients without synd):
- coved type ST elevation with at least 2mm (0.2mV) J-point elevation and gradually descending ST segment followed by negative T-wave
- has a saddle-back pattern with a least 2 mm J-point elevation and at least 1 mm ST elevation with a +ve or biphasic T-wave. Occasionally seen in healthy subjects.
- either a coved (type 1 like) or a saddle-back (type 2 like) pattern, with less than 2 mm J-point elevation and less than 1 mm ST elevation. Not rare in healthy subjects.
This ECG abnormality must be associated with one of the following clinical criteria to make the diagnosis:
- Documented ventricular fibrillation (VF) or polymorphic ventricular tachycardia (VT)
- 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
Management:
- avoid risk factors - excess alcohol, certain drugs Drug usage/avoidance in Brugada, prompt treatment of fevers with anti-pyretics
- quinidine sometimes. Isoprenaline infusion as emergency
- implantable defib, catheter ablation
- ECHO and MRI especially to exclude arrhythmogenic right ventricular cardiomyopathy
- consider genetic testing SCN5A
Mx of Brugada ECG pattern
EMed guidlelines
ANZ Soc of cardiologists - Brugada guidelines 2011