Increased dispersion of atrial repolarization in Brugada syndrome

Patients with Brugada syndrome (BS) often experience atrial fibrillation (AF) and atrial vulnerability, as measured by increased atrial conduction time. To date, however, dispersion of atrial repolarization has not been reported in these patients.

Monophasic action potentials (MAPs) recorded from four sites of the right atrium were analysed in 11 patients (10 men, 1 woman; mean age, 40 ± 9 years) with BS and in 10 controls (8 men, 2 women; mean age, 35 ± 8 years). None of these patients had a history of AF. Monophasic action potentials were recorded during right atrial pacing at a drive cycle length of 600 ms after continuous pacing. Dispersion of MAP duration (D-MAPD90) was defined as the difference between the maximum and minimum MAP duration measured at 90% repolarization (MAPD90). Inducibility of AF and repetitive atrial firing were also determined. The MAPD90 did not differ significantly between the BS and control groups (245 ± 42 vs. 228 ± 24 ms, P = ns), but D-MAPD90 was significantly higher in the BS group (69.1 ± 35.0 vs. 41.4 ± 10.3 ms, P < 0.05). Atrial fibrillation was induced in six BS patients and repetitive atrial firing in four, but neither was induced in any of the control subjects.

The significantly increased dispersion of MAPD90 observed in patients with BS suggests that the heterogeneity of atrial repolarization may contribute to the development of atrial fibrillation in patients with BS.