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

Abstract

Due to safety concerns about available antiarrhythmic drugs (AADs), 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 an emergency department. This multicenter, retrospective registry covered 1365 patients (median [interquartile range] age, 69.0 [61.0-76.0] years, 53.1% men) with new‑onset AF submitted to urgent pharmacological cardioversion. AAD allocation was performed by the attending physician: antazoline alone was utilized in 600 patients (44%), amiodarone in 287 (21%), propafenone in 150 (11%), and ≥2 AADs in 328 patients (24%). Antazoline in monotherapy or combination was administered to 897 patients (65.7%). Matched antazoline and nonantazoline groups were identified using propensity score matching (PSM, n = 330). The primary end point was return to sinus rhythm within 12 hours after initiation of the treatment. Before PSM, antazoline alone was superior to amiodarone (78.3% vs 66.9%; relative risk [RR], 1.17; 95% CI, 1.07-1.28; P <0.001) and comparable to propafenone (78.3% vs 72.7%; RR, 1.08; 95% CI, 0.97-1.20; P = 0.14) in terms of rhythm conversion rate. In the post‑PSM population, the rhythm conversion rate was higher among patients receiving antazoline alone than in the nonantazoline group (84.2% vs 66.7%; RR, 1.26; 95% CI, 1.11-1.43; P <0.001), and the risk of adverse events was comparable (P = 0.2). Antazoline appears to be an efficacious agent for termination of AF in real‑world setting. Randomized controlled trials are required to evaluate its safety in specific patient populations.