Some patients with features of Brugada Syndrome can have a normal ECG most of the time.
Features of the concealed Brugada Syndrome:
(1) normal ECG in the absence of an unmasking agent (drug or fever)
(2) exposure to an unmasking agent results in a Brugada type 1 or 2 ECG pattern (ST-segment elevation in precordial leads V1 to V3)
(3) removal of unmasking agents is followed by normalization of the ECG pattern
(4) variable family history of syncope and/or sudden death
(5) increased risk of ventricular arrhythmia and sudden death
Provocative testing can be done with a sodium channel blocker:
(1) ajmaline
(2) flecamide
(3) procainamide
(4) pilsicainide
