Objectives: To evaluate the significance of conduction delay (CD) in the right ventricle (RV) in Brugada syndrome (BS) as a marker for risk stratification of sudden death.
Methods: Twenty-five patients with BS (7 with documented ventricular fibrillation (VF), 8 with syncope, and 10 without symptoms) and 10 control subjects were paced from the RV apex using 8 beats of drive pacing and a single extra-stimulus. CDs in the right ventricular outflow tract (RVOT) (CD-RV) and in the lateral left ventricle (L-LV) (CD-LV), and the local electrogram durations at a single extra-stimulus in RVOT (D-RV) and L-LV (D-LV) were calculated. We also evaluated changes in 12-lead ECG parameters in 16 patients with BS after pilsicainide challenge test (Pilsicainide-test).
Results: Maximal CD-RV and maximal D-RV were significantly larger than maximal CD-LV and maximal D-LV in BS (26 +/- 10 and 105 +/- 15 vs 20 +/- 6 and 92 +/- 15 ms, P < 0.05, respectively). Maximal CD-RV and maximal D-RV in patients with documented VF were the largest among the 3 groups. There was a significant positive correlation between maximal CD-RV or maximal D-RV and changes in QRS duration in leads V2 and V5 and in S wave duration in lead II and V5 after Pilsicainide-test (CD-RV; r = 0.54, 0.51, 0.56, and 0.53: D-RV; r = 0.55, 0.5, 0.57, and 0.53, P < 0.05, respectively). In control subjects, there were no significant differences.
Conclusions: CD in RV was a useful marker for identifying high-risk patients with BS. CD in the RV, especially in the RVOT epicardium, may be related to arrhythmias in BS.