In 1992 we described a new syndrome consisting of syncopal episodes and/or 
sudden death in patients with a structurally normal heart and a characteristic 
electrocardiogram displaying a pattern resembling right bundle branch block with 
an ST segment elevation in leads V1 to V3. In 1998 it was described that the 
disease is genetically determined with an autosomal dominant pattern of 
transmission. Three different mutations have been identified. All three 
mutations affect the structure and the function of the sodium channel SCN5A. Two 
mutations result in total loss of function of the sodium channel. The other 
mutation results in acceleration of the recovery of the sodium channel from 
inactivation. The disease causes 4 to 10 sudden deaths per 10,000 inhabitants 
per year in areas like Thailand and Laos. Up to 50% of the yearly sudden deaths 
in patients with a normal heart might be caused by this syndrome. The diagnosis 
is easily made by means of the electrocardiogram (ECG). The presence of 
concealed and intermittent forms, however, makes the diagnosis difficult in some 
patients. The ECG can be modulated by changes in autonomic balance and the 
administration of antiarrhythmic drugs. Beta-adrenergic stimulation normalises 
the ECG, while i.v. ajmaline, flecainide or procainamide accentuate the ST 
segment elevation and are capable of unmasking concealed and intermittent forms 
of the disease. The prognosis is poor for patients who do not receive an 
implantable cardioverter-defibrillator. Antiarrhythmic drugs like amiodarone or 
beta-blockers do not prevent sudden death in symptomatic or asymptomatic 
individuals.