Ranolazine terminates atrial flutter and fibrillation in a canine model

BACKGROUND Ranolazine has been shown to have antiarrhythmic properties. OBJECTIVE We tested the hypothesis that intravenous ranolazine would terminate induced atrial flutter (AFL) or atrial fibrillation (AF) in the canine sterile pericarditis model. METHODS In 6 dogs with sterile pericarditis, we performed electrophysiological measurements of the atrial effective refractory period (AERP) and conduction time (CT) while pacing from the right atrial appendage, Bachmann bundle, and the posteroinferior left atrium at cycle Lengths (CLs) of 400, 300, and 200 ms before and after the administration of ranolazine. In 13 induced episodes of AFL (n = 9) and AF (n = 4), ranolazine was administered intravenously as a 3.2 mg/kg bolus, followed by a maintenance infusion of 0.17 mg/(kg . min). Six episodes (4 AFL and 2 AF) were induced in the open-chest state to perform simultaneous, multisite (486 electrodes), epicardial mapping of the arrhythmia and its termination. RESULTS Ranolazine terminated 7 of 9 AFL and 3 of 4 AF episodes. Ranolazine significantly prolonged the AFL CL by a mean of 43 ms (P < .001) and the AF CL by a mean of 34 ms (P < .01). The AERP was prolonged (P < .05 overall), and the atrial capture threshold increased minimally (P < .01 for all). Ranolazine prolonged CTs (P < .01 overall). During open-chest, multisite mapping, block in the region of slow conduction in the reentrant circuit terminated AFL and interruption of the regular driver terminated AF. CONCLUSION Ranolazine terminated AFL/AF in our canine sterile pericarditis model by interrupting the regular driver. Ranolazine was found to significantly prolong the AERP, CT, and tachycardia CLs.