Different Effect of the Pure Na⁺ Channel-Blocker Pilsicainide on the ST-Segment Response in the Right Precordial Leads in Patients With Normal Left Ventricular Function

Abstract

Background The response of the ST-segment in the right precordial leads to Na⁺ channel blockers in patients without structural heart disease and a typical Brugada-type ECG has not been fully elucidated. Methods and Results A pilsicainide challenge test was performed in 161 patients and according to recently established ECG criteria and an organized computer algorithm, the ST morphology was classified and the maximum increase in the J wave amplitude (maxΔJ) from the standard and high right precordial leads V_1-3 was examined. Before the test, subjects exhibiting type 1 ECG in the standard leads were excluded. After administering pilsicainide, type 1 ECGs in the standard leads were observed in 31 cases and a maxΔJ of ≥200 μV was observed in 29 cases (23 type 1, 2 type 2/3 and 4 normal ECGs). In the additional higher right precordial leads, type 1 ECGs were observed in 55 cases and a maxΔJ of ≥200 μV was observed in 45 cases (42 type 1 and 3 type 2/3 ECGs). Conclusions A maxΔJ ≥200 μV induced by pilsicainide, including that measured in the high right precordial leads, was associated with a change mainly to a type 1 ECG. (Circ J 2007; 71: 57 - 62)