Atrial electrophysiological abnormality in patients with Brugada syndrome assessed by P-wave signal-averaged ECG and programmed atrial stimulation.

BACKGROUND: There is evidence that some patients with Brugada syndrome (BS) exhibit atrial tachyarrhythmias including paroxysmal atrial fibrillation. We investigated whether BS associated not only with vulnerability to ventricular fibrillation, but also with vulnerability to atrial fibrillation.

METHODS AND RESULTS: In 15 patients with BS and Brugada-type electrocardiogram (ECG) (14 men, 1 woman; age 52.8+/-12.9 years) and 15 age-matched control patients (12 men, 3 women; age 50.9+/-18.9 years), the P-wave signal-averaged ECG was recorded, and the filtered P-wave duration was derived from the vector magnitude obtained by X, Y, Z leads. In 11 of the 15 patients with BS and Brugada-type ECG, invasive electrophysiologic testing was conducted. Filtered P-wave duration was significantly increased in patients with BS and Brugada-type ECG in comparison with control subjects (143.2+/-12.9 vs 129.6+/-10.1 ms, p<0.001). Ventricular late potential (root mean square voltage <20 muV in the last 40 ms and <40 muV at a low amplitude signal duration >38 ms) was present in 10 of the 12 BS patients in whom a QRS wave signal-averaged electrogram was also recorded. In all 11 patients with Brugada-type ECG who underwent electrophysiologic testing, sustained atrial fibrillation (>5 min) was induced by 1 or 2 atrial extrastimuli. In 10 of these 11 patients, ventricular fibrillation was also induced by 2 or 3 right ventricular extrastimuli.

CONCLUSIONS: The electrical abnormality in BS is not limited to the ventricular level; similar changes occur in the atria. Such abnormal conduction properties could be a substrate for re-entrant atrial tachyarrhythmias.