Effects of the Na+ Channel Blocker Pilsicainide on the Electrophysiologic Properties of Pulmonary Veins in Patients with Atrial Fibrillation

Introduction: Na+ channel blockers are used to treat atrial fibrillation (AF). However, the effects of Na+ channel blockers on the electrophysiologic properties of pulmonary veins (PVs) are not well characterized. The aim of the present study was to evaluate the effect of the pure Na+ channel blocker pilsicainide on the PVs. Methods and Results: PV mapping using a basket catheter was performed in 28 patients with paroxysmal AF. Twenty‐eight PVs, including 20 left superior and 8 right superior PVs, were studied. Programmed stimulation was performed in the distal PV and PV‐left atrial (LA) junction before and after infusion of pilsicainide (1 mg/kg). Pilsicainide significantly prolonged the effective refractory period (ERP) of the distal PV from 163 ± 44 msec to 192 ± 53 msec (P < 0.001), PV‐LA junction from 227 ± 48 msec to 235 ± 52 msec (P < 0.05), and LA appendage from 225 ± 55 msec to 245 ± 48 msec (P < 0.05). Pilsicainide significantly prolonged the conduction time from the distal PV to PV‐LA junction from 45 ± 14 msec to 70 ± 26 msec (P < 0.0001). In 3 of 5 patients who experienced AF termination with pilsicainide, PV‐LA conduction block was observed just before AF termination. Conclusions: Pilsicainide can modify ERP heterogeneity and conduction properties in the PV and at the PV‐LA junction. Because the PV and PV‐LA junction have important roles as substrates for AF maintenance, pilsicainide may terminate AF by pharmacologic PV isolation.