Asymptomatic individuals with a Brugada electrocardiogram should undergo electrophysiological testing

The Brugada syndrome is an inherited cardiac arrhythmia disorder caused by mutations in the cardiac sodium channel gene SCN5A.

Carriers of the disease may develop a variety of cardiac arrhythmias including supraventricular tachycardias, AV conduction defects or block, sick sinus syndrome with atrial standstill, ventricular tachycardia and ventricular fibrillation.

The disease is characterised by the lack of structural heart disease and an ECG with a characteristic coved-type ST segment elevation in leads V1, V2 and V3. Syncopal episodes and paroxysmal palpitations are the only symptoms attributable to the disease that may act as a warning before (aborted) sudden arrhythmic death occurs.
General agreement exists that an implantable cardioverter defibrillator must be given to patients with the Brugada syndrome resuscitated from ventricular fibrillation.

However, controversy exists on how to approach the individual with a Brugada-like ECG who has never developed ventricular fibrillation.

For 12 years now we have been maintaining a large data base of individuals and patients with a diagnostic Brugada-like ECG.

At the last follow-up we analysed the status of 724 individuals of whom 547 (75%) had no previous cardiac arrest. A subgroup of 167 asymptomatic individuals was also identified who had no family history of sudden death, or Brugada syndrome and were considered fortuitous, isolated cases.

Of the 167 fortuitous cases with a Brugada-like ECG, 11 (6.5%) developed (aborted) sudden death. In these non-familial asymptomatic individuals the best predictor of spontaneous ventricular fibrillation was the inducibility of a sustained arrhythmia during programmed ventricular stimulation (p<0.008).
Fortuitous cases studied by programmed ventricular stimulation and inducible stimulation usually received an implantable defibrillator and survived when ventricular fibrillation occurred (6 individuals). There were 5 effective sudden deaths in the 167 fortuitous cases.

None of the 5 had had an electrophysiological study done and none had had a defibrillator implanted (see example in figure 1). For the whole group without previous cardiac arrest, logistic regression analysis showed that a previous history of syncope carries a sufficient risk of (aborted) sudden death (1.2 to 27.2% at 3 years follow-up) such as to recommend an implantable defibrillator independently from the results of programmed ventricular stimulation.

In asymptomatic individuals (including the fortuitous, non-familial cases) programmed ventricular stimulation helps to stratify the risk of (aborted) sudden death and to identify candidates to prophylactic treatment, the hazard ratio of inducible individuals being 8.33 (95% confidence intervals 2.8-25.0) as compared to the non-inducible ones.



Figure 1. 34 years old male, asymptomatic, no family history, routine ECG. Echocardio normal, Holter normal, stress test normal. EPS advised, refused by the patient. Eight months later: sudden arrhythmic death at 1 a.m., VF when EMS arrives. Necropsy: normal heart, normal coronary arteries. No other cause for sudden death: probably arrhythmic

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