Relationship between dominant prolongation of the filtered QRS duration in the right precordial leads and clinical characteristics in Brugada syndrome

SAECG and EPS in Brugada Syndrome. Background: Electrical abnormalities in the RVOT may be involved in Brugada syndrome. Objectives: We investigated the relationship between the signal-averaged ECG (SAECG) and electrophysiologic study (EPS), especially focusing on conduction delay in the outflow tract of the right ventricle (RVOT) and its contribution to clinical characteristics. Methods: Twenty-four patients with Brugada syndrome (23 men and 1 woman; 61 +/- 16 years old) were studied. We assessed the presence of late potential (LP) in SAECG and the filtered QRS duration in the right precordial leads (V-1 or V-2; RfQRS) and in the left precordial leads (V-5 or V-6; LfQRS) and the difference between them. In 18 patients, SAECG was evaluated for an LP on three separate occasions. Results: SAECG was positive for LP in 15 patients at least once; and in 7 patients, SAECG was positive for an LP on multiple occasions, and 6 of 7 patients (86%) had a history of cardiac arrest. The difference between RfQRS and LfQRS was significantly greater in patients with cardiac arrest than in patients with syncope or in asymptomatic patients; 29 +/- 10, 14 +/- 11 (P < 0.01), and 7 +/- 5 msec (P < 0.001), respectively. All patients were alive and one patient with cardiac arrest had an appropriate VF therapy delivered by the ICD. Conclusions: The dominant prolongation of the filtered QRS duration in the right precordial leads may be related to the risk of arrhythmic event in Brugada syndrome.