Brugada pattern

Definition

The diagnostic type 1 pattern is coved ST-segment elevation of at least 2 mm (0.2 mV) followed by a negative T wave in one or more of the right precordial leads V1 to V2, recorded in the standard 4th or a higher (2nd or 3rd) intercostal space. Two mechanisms are proposed: abnormal repolarization of the right ventricular epicardium and slow conduction (abnormal depolarization) in the right ventricular outflow tract. The main known gene is SCN5A, whose loss-of-function variants reduce the sodium current, but SCN5A variants are found in fewer than 30 percent of clinically diagnosed patients. The type 1 pattern is the ECG hallmark of Brugada syndrome, which carries a risk of polymorphic ventricular tachycardia, ventricular fibrillation and sudden death; the non-diagnostic type 2 (saddleback) pattern cannot substitute for type 1 unless fever or a sodium-channel-blocker test converts it to type 1.

Clinical noteUnder the 2022 ESC guideline only a spontaneous type 1 pattern establishes Brugada syndrome on its own (in a person with no other heart disease). A type 1 pattern seen only during fever or after a sodium-channel-blocking drug establishes it together with survived cardiac arrest from ventricular fibrillation or polymorphic ventricular tachycardia, makes it likely together with arrhythmic syncope, a family history of Brugada syndrome or a family history of sudden death before age 45, and on its own makes it only a possible diagnosis. Electrolyte shifts such as hyperkalemia or hypercalcemia and other conditions can also produce a Brugada-like ECG.