Efficacy and safety of antazoline for cardioversion of atrial fibrillation: propensity score matching analysis of multicenter registry (CANT II Study)

Due to safety concerns about available anti-arrhythmic drugs (AAD), reliable agents for termination of atrial fibrillation (AF) are requisite. The aim of the study was to evaluate the efficacy and safety of antazoline, a first generation antihistamine, for cardioversion of recent-onset AF in the setting of emergency department. This multicentre retrospective registry covered 1365 patients (median age 69.0 (61.0-76.0) years, 53.1% men) with new-onset AF submitted to urgent pharmacological cardioversion. AAD allocation was selected by attending physician: antazoline alone was utilized in 600 patients (44%), amiodarone in 287 (21%), propafenone in 150 (11%) and ≥2 AAD in 328 patients (24%). Antazoline in monotherapy or combination was administered to 897 patients (65.7%). Matched antazoline and non-antazoline groups were identified using propensity score matching (PSM, N = 330). The primary endpoint was return of sinus rhythm within 12 hours after initiation of treatment. Before PSM, antazoline alone was superior to amiodarone [78.3% vs 66.9%; relative risk (RR) 1.17;95% confidence interval (CI) 1.07-1.28, P