You may want to read this answer from the Expert Forum by Dr. Varma:
http://www.medhelp.org/posts/Heart-Rhythm/Lone-Atrial-Fibrillation-and-Brugada-Syndrome/show/1630804
Brugada Syndrome is a congenital syndrome (not using the word disease or disorder here because it does NOT have to provide any symptoms at all through your life). It manifest on EKG with atypical right bundle branch block and downsloping ST elevation in the right leads, but those changes aren't always present.
During an EP study you will get a substance that blocks sodium channels (ajmaline or maybe flecainide(?)) to look for EKG changes and possibly provoke arrhythmias. But you need to be aware of the following:
1) Brugada that reveals this rarely, often provides little risk (see doctor's reply above)
2) Your last cardiologist may, in theory, be wrong, if all other cardiologist said you did not have Brugada.
If it turns out you do have Brugada, it may be a good idea to watch out for medication that blocks sodium channels (some anti-anxiety drugs have this ability and not all doctors know this, at least that's the case in my country).