Abstract 636: Conduction Delay in Right Ventricle as a Marker for Identifying High-Risk Patients in Brugada Syndrome
BACKGROUND In Brugada syndrome (BS), abnormal conduction delay in right ventricle has been reported. However, the meaning of the conduction delay for risk stratification in BS is still unclear.
OBJECTIVES To evaluate the significance of conduction delay in patients with BS as a marker for risk stratification.
METHODS Twenty-four patients with BS in whom pilsicainide challenge test was performed (documented VF: N = 7, syncope: N = 7, and asymptomatic: N = 10) were paced from right ventricular apex (RVA), using a basic cycle length of 500ms (8 beats) and a single extrastimulus. A 2.5-French 16-electrode catheter was positioned into the coronary sinus and the great cardiac vein to record intracardiac electrograms on the epicardial sites in right ventricular outflow tract area (RVOT) and lateral left ventricle (l-LV). We measured the conduction time from the stimulus artifact at RVA to the epicardial ventricular electrogram at RVOT or l-LV. The conduction delay between RVA and RVOT (CD-RV) or between RVA and l-LV (CD-LV) was defined as the time interval between the ventricular response at RVOT (RV-V1V2) or at l-LV (LV-V1V2) and the stimulus coupling interval (S1S2) at RVA, respectively (CD-RV; RV-V1V2 minus S1S2, and CD-LV; LV-V1V2 minus S1S2). We also measured 12-lead ECG parameters at baseline and after pilsicainide challenge test, and evaluated the differences of the ECG parameters before and after pilsicainide challenge test.
RESULTS Max CD-RV was significantly larger than max CD-LV in all patients (28±9 vs 19±7 ms, p<0.05). Max CD-RV in patients with documented VF was significantly larger than that in patients without (35±10 vs 25±7 ms, p<0.05). However, there was no significant difference in max CD-RV and CD-LV between patients with induced VF and those without (30±9 and 20±5 vs 26±7 and 21±7 ms, p=NS). There was significant positive correlation between max CD-RV and the differences in QRS duration in leads V1, V2, and V6 after pilsicainide administration (r = 0.51, 0.53, and 0.48, respectively, p<0.05).
CONCLUSIONS The conduction delay in right ventricle (RV) was a useful marker for identifying high-risk patients in BS. The conduction delay at RV may be related to depolarization abnormality due to sodium channel dysfunction in BS.