Patients hospitalized with paroxysmal atrial fibrillation and flutter to restore sinus rhythm will be randomized into two groups: one will be cardioversion with refralon and the other with amiodarone

Atrial fibrillation (AF) and flutter (AFL) are the most common types of arrhythmia in clinical practice. Both electrical and medical cardioversion can be used to restore sinus rhythm. Currently, the most studied and commonly used drug for pharmacological cardioversion of paroxysms of AF/AFL is amiodarone, which belongs to class III antiarrhythmic drugs. The highest recovery rates of sinus rhythm (SR) (>90%) are achieved with intravenous administration of amiodarone at a dose of more than 1500 mg / day or up to a maximum of 3000 mg / day. However, most commonly, amiodarone is used at a standard dose of 5 mg/kg body weight, with an efficacy of 34-69%. In 2014, a new Russian class III antiarrhythmic drug, Refralon, was registered. In 2020, the drug was included in the National Clinical Guidelines "Atrial Fibrillation and Flutter", approved by the Ministry of Health of the Russian Federation. When using refralon in doses from 10 to 30 μg/kg, SR recovery was noted in 91.6% of patients with persistent AF/AFL in 50% of patients SR restored within 15 minutes from the start of the drug administration.

Randomized trials comparing the efficacy and safety of refralon with other antiarrhythmic drugs have not been conducted. It is extremely important to directly compare the efficacy and safety of these two drugs in patients with paroxysmal AF in a prospective randomized study.

Inclusion Criteria:

1. Paroxysmal form of AF/AFL;
2. Indications for SR recovery

Exclusion Criteria:

1. Arrhythmogenic effect of refralon, amiodarone and other antiarrhythmic drugs in history;
2. Chronic kidney disease with a decrease in glomerular filtration rate less than 30 ml / min / 1.73 m2;
3. Chronic heart failure (functional class IV);
4. Atrioventricular blockade of 2-3 degrees (with the exception of patients with an implanted pacemaker);
5. Dysfunction of the sinoatrial node (with the exception of patients with an implanted pacemaker);
6. Bradysystolic atrial fibrillation (heart rate <50 beats/min);
7. Duration of the QT interval >440 ms;
8. Hemodynamic instability requiring emergency cardioversion;
9. Contraindications to anticoagulant therapy;
10. Thyrotoxicosis or decompensated hypothyroidism;
11. Uncorrected electrolyte disturbances at the time of cardioversion (potassium level less than 3.5 mmol/l);
12. Pregnancy and breastfeeding period.