Intravenous antazoline, a first-generation antihistaminic drug with antiarrhythmic properties, is a suitable agent for pharmacological cardioversion of atrial fibrillation induced during pulmonary vein isolation due to the lack of influence on atrio-venous conduction and high clinical effectiveness (AntaEP Study).

Aims: Antazoline is a first-generation antihistaminic drug used primarily in eye drop formulations. When administered intravenously, antazoline displays antiarrhythmic properties resulting in a rapid conversion of recent-onset atrial fibrillation (AF) to sinus rhythm (SR). The aim of the study was to assess the influence of antazoline on atrio-venous conduction and other electrophysiological parameters in patients undergoing AF ablation.

Methods: An experimental prospective study. Patients scheduled for the first-time AF ablation, in SR and not on amiodarone were enrolled. Atrio-venous conduction assessment and invasive electrophysiological study (EPS) were performed before and after intravenous administration of 250 mg of antazoline. In case of AF induction during EPS, antazoline was administered until conversion to SR or a cumulative dose of 300 mg.

Results: We enrolled 14 patients: 13 (93%) men, mean age 63.4 (59.9-66.8) years, mean CHA DS -VASc score 1.6 (1.0-2.2). Antazoline was administered in a mean dose 257.1 (246.7-267.6) mg. Pulmonary vein potentials and atrial capture during pulmonary vein stimulation were present before and after the administration of antazoline. Wenckebach point and atrial conduction times did not change significantly, but atrio-ventricular node effective refractory period improved-324.7 (275.9-373.5) ms vs 284.3 (256.2-312.4) ms, P = 0.02. Antazoline was effective in all 5 (100%) cases of AF induction during EPS. There were no serious adverse events.

Conclusion: Due to the lack of influence on atrio-venous conduction and high clinical effectiveness, antazoline may be suitable for pharmacological cardioversion of AF occurring during AF ablation.