Cardiology · Medical Literature
Role of antazoline in cardioversion of atrial fibrillation: A PRISMA-compliant systematic review and meta-analysis.
Abstract
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. Antazoline, a first-generation antihistamine with antiarrhythmic properties, has shown efficacy in the rapid conversion of recent-onset AF to sinus rhythm; however, direct comparative evidence against standard antiarrhythmic agents remains limited. This study aims to systematically evaluate the efficacy and safety of antazoline for pharmacological cardioversion of AF, in comparison with standard antiarrhythmic agents such as amiodarone and propafenone. The methodology of this systematic review and meta-analysis adhered to the preferred reporting items for systematic reviews and meta-analyses guidelines. A systematic search was conducted in ScienceDirect, Embase, PubMed, and Cochrane Library from inception to April 2025, including citation and reference screening. Statistical analyses were performed using R version 2025.05.0 + 496. From 172 records, 5 studies comparing antazoline with propafenone (n = 5) or amiodarone (n = 3) for AF were included. For antazoline vs propafenone, conversion to sinus rhythm favored antazoline (risk ratio [RR] 1.13 [95% confidence interval (CI): 1.04-1.23], P = .017). No significant difference was observed in time to conversion (mean difference -10.98 [95% CI: -124.93-102.98], P = .436), bradycardia (RR 0.84 [95% CI: 0.35-2.03], P = .478), hypotension (RR 0.40 [95% CI: 0.14-1.12], P = .056), or other adverse events (RR 1.24 [95% CI: 0.01-247.13], P = .694). For antazoline vs amiodarone, conversion to sinus rhythm favored antazoline (RR 1.22 [95% CI: 1.08-1.36], P = .018, I2 = 0%), with no significant differences in bradycardia (RR 1.36 [95% CI: 0-1072357.09], P = .823) or hypotension (RR 1.05 [95% CI: 0.04-26.16], P = .877). Antazoline might be more effective than propafenone and amiodarone in achieving sinus rhythm in AF, with no significant differences in safety outcomes.
Clinical relevance
Atrial fibrillation is the most common sustained cardiac arrhythmia, and rapid pharmacological cardioversion remains a critical management strategy in the acute setting. Antazoline, a first-generation antihistamine with underrecognized antiarrhythmic properties, represents a potentially superior alternative to standard agents (amiodarone, propafenone), yet comparative evidence has been sparse and fragmented. This PRISMA-compliant systematic review and meta-analysis consolidates the available evidence through April 2025, offering cardiologists and emergency physicians a more rigorous basis for considering antazoline in recent-onset AF cardioversion protocols.
Key findings
1. Antazoline vs. propafenone — conversion to sinus rhythm: Antazoline was significantly more effective (RR 1.13, 95% CI: 1.04–1.23, P = .017), representing a 13% relative increase in cardioversion success across 5 comparative studies. 2. Antazoline vs. amiodarone — conversion to sinus rhythm: Antazoline demonstrated superior efficacy (RR 1.22, 95% CI: 1.08–1.36, P = .018, I² = 0%), representing a 22% relative increase in cardioversion success with no between-study heterogeneity across 3 comparative studies. 3. Time to cardioversion (antazoline vs. propafenone): No statistically significant difference was observed (mean difference −10.98 minutes, 95% CI: −124.93 to 102.98, P = .436). 4. Bradycardia risk: No significant difference vs. propafenone (RR 0.84, 95% CI: 0.35–2.03, P = .478) or vs. amiodarone (RR 1.36, 95% CI: 0–1,072,357.09, P = .823), though the latter CI is extremely wide, indicating very sparse event data. 5. Hypotension risk: No significant difference vs. propafenone (RR 0.40, 95% CI: 0.14–1.12, P = .056) or vs. amiodarone (RR 1.05, 95% CI: 0.04–26.16, P = .877); a trend toward reduced hypotension vs. propafenone approached but did not reach significance. 6. Other adverse events (antazoline vs. propafenone): No significant difference detected (RR 1.24, 95% CI: 0.01–247.13, P = .694), though the extremely wide CI reflects very limited event data and substantial uncertainty.
Practice implications
Clinicians managing recent-onset AF in the acute or emergency setting may consider antazoline as a pharmacological cardioversion agent, particularly when standard agents such as amiodarone or propafenone are relatively contraindicated or have previously failed, given its statistically superior conversion rates and a comparable safety profile for bradycardia and hypotension. However, the evidence base is limited to 5 studies with small pooled sample sizes, very wide confidence intervals for safety endpoints, and no NNT data reported, mandating caution before broad protocol adoption — antazoline should currently be viewed as a promising adjunct or alternative rather than a definitive first-line replacement. Larger, prospective, randomized controlled trials with standardized dosing regimens, clearly defined patient eligibility criteria (AF duration, structural heart disease status), and systematic adverse event reporting are urgently needed to validate these findings and establish evidence-based dosing and monitoring guidelines.