The purpose of this study is to determine if quinidine therapy (not guided by the results of electrophysiologic studies) will reduce the long-term risk of arrhythmic events in asymptomatic Brugada Syndrome.

Inclusion Criteria:

1. Patients with Asymptomatic Brugada syndrome.

   • "Brugada syndrome" is defined as the presence of a Type-I Brugada electrocardiogram [coved ST-segment elevation ≥2 mm (0.2 mV) in V1, V2 or V3] either spontaneously (at rest, in the baseline state or during a febrile episode) or following a standard drug-challenge test (with flecainide, ajmaline, procainamide, or pilsicainide) and recorded either with standard electrode position or with the precordial electrodes placed on the second or third intercostal space. Negative T waves in the precordial leads are not required to define a Type I electrocardiogram.
   • "Asymptomatic patients" will be defined as patients without a history of cardiac arrest, a history of "arrhythmic syncope" or a history of "suspected arrhythmic syncope." Arrhythmic syncope" is a syncope occurring during documented ventricular tachyarrhythmias. "Suspected arrhythmic syncope" is syncope without documented arrhythmias believed to be caused by a tachyarrhythmia based on clinical judgment. In other words, patients with typical vagal syncope will be counted as "asymptomatic" and will be accepted to the registry whereas patients with a clinical history suggesting "syncope other than vagal syncope" will not be accepted to this Registry.
   • Genetic confirmation (identification of a disease-causing mutation) will not be required for establishing the diagnosis of Brugada syndrome but will be recorded when present.

2. Patients with Questionable Brugada Syndrome who are asymptomatic.

   • Patients with "Questionable Brugada Syndrome" are defined as patients with type II or III electrocardiogram who have an inconclusive result during a drug challenge with a sodium channel blocker. "Asymptomatic" is defined as above.
   • Genetic testing will not be required. However, patients with "Questionable Brugada" based on electrocardiographic criteria will be defined as "Patients with Brugada Syndrome" if a disease-causing mutation is identified.

Exclusion Criteria:

1. A history of cardiac arrest, "arrhythmic syncope" or "suspected arrhythmic syncope" (as defined above).
2. Evidence of organic heart disease. The evaluation considered mandatory for excluding heart disease will consist of electrocardiogram, echocardiogram and exercise stress testing. Additional tests will be performed only if clinically indicated.
3. Evidence of non-cardiac disease likely to affect 5-year survival.