It is planned to evaluate the efficacy and safety of the class III antiarrhythmic drug refralon as a drug for pharmacological cardioversion in patients with recurrent atrial fibrillation (AF) and atrial flutter (AFL) after catheter ablation.

Atrial fibrillation and atrial flutter are the most common arrhythmias among the adult population of the world, their share in the population is from 2 to 4% and continues to grow.

Modern highly effective methods of minimally invasive surgical treatment of these types of arrhythmia are currently catheter radiofrequency ablation and balloon cryoablation of the pulmonary veins. According to the CABANA study, catheter interventions reduce the risk of recurrent AF/AFL by 47%, significantly improving arrhythmia tolerance and improving the quality of life of patients.

An important problem is the recurrence of arrhythmia after the intervention, the frequency of recurrence of AF/AFL in the first 3 months after ablation (the so-called early recurrence) is 50-60%. In many patients, these recurrence are accompanied by severe clinical manifestations, which require pharmacological or electrical cardioversion.

In order to restore sinus rhythm, electrical cardioversion is most often used, the effectiveness of which is 90-92%.

An alternative to electrical cardioversion is pharmacological cardioversion, however, antiarrhythmic drugs used in wide clinical practice can restore sinus rhytm (SR) only in patients with recent AF paroxysms.

In 2014, a new Russian class III antiarrhythmic drug, Refralon, was registered. The effectiveness of the Refralon as a means of cardioversion in patients with persistent AF/AFL is 90%, in patients with paroxysmal AF/AFL - 95%.

At present, there is no information on the efficacy and safety of the use of refralon in patients with AF / AFL who underwent catheter ablation. The growing number of catheter ablation in the world dictates the to study new approaches to performing cardioversion in this cohort of patients.

Inclusion Criteria:

2. Patients with paroxysmal or persistent forms of AF/AFL and early (less than 90 days) or late (more than 90 days) arrhythmia recurrence after catheter radiofrequency ablation or balloon cryoablation of pulmonary veins.

3. Indications for SR recovery. 4. Consent of the patient.

Exclusion Criteria:

1. Arrhythmogenic effect of antiarrhythmic drugs III class 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. Acute coronary syndrome;
5. Bronchial asthma of an uncontrolled course and / or severe respiratory failure.
6. The need for the use of drugs that increase the duration of the QT interval drugs without the possibility of withdrawal
7. Atrioventricular blockade of 2-3 degrees (with the exception of patients with an implanted pacemaker);
8. Dysfunction of the sinoatrial node (with the exception of patients with an implanted pacemaker);
9. Bradysystolic atrial fibrillation (heart rate <50 beats/min);
10. Duration of the QT interval >440 ms;
11. Hemodynamic instability requiring emergency cardioversion;
12. Contraindications to anticoagulant therapy;
13. Thyrotoxicosis or decompensated hypothyroidism;
14. Uncorrected electrolyte disturbances at the time of cardioversion (potassium level less than 3.5 mmol/l);
15. Pregnancy and breastfeeding period.