Inferior and lateral electrocardiographic repolarization abnormalities in Brugada syndrome.

Background: Repolarization abnormalities in the inferior-lateral leads in Brugada syndrome (BS) have not been systematically investigated.
Methods and Results: 280 patients (age, 41+/-18 years; 168 males) with BS were screened for inferior-lateral repolarization abnormalities. The repolarization abnormalities were classified either as early repolarization pattern or coved > or = 2-mm Brugada pattern and as spontaneous or class I antiarrhythmic drug (AAD) induced. Thirty-two patients (11%) had inferior-lateral spontaneous early repolarization pattern. These patients were less likely to be asymptomatic at first presentation (13 of 32 versus 156 of 248 patients, P=0.02), and spontaneous type I ECG was more frequent among them (38% versus 21%, P=0.05). The spontaneous early repolarization pattern occurred more frequently among patients with BS than in 283 family members not having BS (11% versus 6%, P=0.03). Class I AAD administration provoked inferior-lateral coved Brugada pattern in 13 patients with BS. These patients had longer baseline PR intervals (206+/-48 versus 172+/-31 ms, P<0.001) and class I AAD-induced QRS interval prolongation (108 to 178 versus 102 ms to 131 ms, P<0.001). In 3 patients, the class I AAD-provoked coved Brugada pattern was only present in the inferior leads.
Conclusions: Inferior-lateral early repolarization pattern occurs spontaneously relatively frequently in BS. These patients have a more severe phenotype. Class I AAD administration provokes inferior-lateral coved Brugada pattern in 4.6% of patients. We report for the first time 3 patients in whom the class I AAD-provoked coved Brugada pattern was only observed in the inferior leads.