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

INTRODUCTION: Due to safety concerns about available antiarrhythmic drugs (AADs), reliable agents for termination of atrial fibrillation (AF) are requisite. OBJECTIVES: 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. PATIENTS AND METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.