Antazoline in Rapid Cardioversion of Paroxysmal Atrial Fibrillation

Antazoline is a first generation antihistaminic agent with chinidin-like properties. When administered intravenously, antazoline exerts a strong antiarrhythmic effect on supraventricular arrhythmia especially on atrial fibrillation (AF) facilitating rapid conversion to sinus rhythm. Despite relative lack of published data antazoline is marketed in Poland and widely used in cardiology wards and emergency rooms due to its efficacy, safety and rapid onset of action within minutes of administration.

To show superiority of antazoline over placebo a sample size of 80 patients was calculated based on following assumptions: two-tailed test, a type I error of 0.01, a power of 90%, efficacy of placebo 5%, efficacy of antazoline 50% and 20% drop-out rate to fulfill the criteria of intention-to-treat analysis. Due to presumed lack of statistical power the secondary end points and safety endpoints will be considered exploratory.

Inclusion criteria

• Written informed consent for participating in the study and written standard version of informed consent for cardioversion accepted in Institute of Cardiology, Warsaw, Poland
• Age above 18 and good general condition
• Potassium level over 3.5 mmol/l
• Stable cardio-pulmonary state on enrollment
• In case of unclear history of heart failure or suspicion of impaired left ventricle function echocardiography is indicated prior to enrollment
• A long-term antiarrhythmic drug therapy is allowed

Exclusion criteria

• Lack of written informed consent
• Antazoline allergy
• AF related to significant valvular disease
• Clinically significant heart failure or ejection fraction < 55%
• Diastolic blood pressure (BP) < 100mmHg
• History of significant bradyarrhythmia not treated with permanent pacemaker
• QT prolongation over 440ms or QTc (Bazett's formula) over population norm
• Tachycardia > 160'
• Advanced liver or kidney failure
• Acute coronary syndrome, coronary artery by-pass graft, stroke or transient ischemic attack within 30 days before enrollment
• Preexcitation in ECG not treated by radiofrequency ablation of accessory pathway
• Signs and symptoms of ischemia related to AF
• An investigational drug used within 30 days before enrollment
• Pregnancy or breast feeding