The efficacy and safety of anticoagulation therapy using dabigatran in comparison with warfarin will be evaluated in patients with atrial fibrillation after mitral valve prosthetic replacement concomitant with Cox-Maze procedure.

Patients with prosthetic mitral valves need a long-term anticoagulation therapy. After mitral valve replacement using mechanical prostheses warfarin is administrated during the whole life. Biological prostheses allows do discontinue anticoagulation 3 months after surgery in the absence of other risk factors of thrombosis especially atrial fibrillation. The common approach to patients with mitral valve disease and atrial fibrillation is mitral valve prosthetic replacement concomitant to Cox-Maze procedure. This allows to maintain sinus rhythm in 65-80% of patients. In the study the safety and efficacy of dabigatran in comparison with warfarin will be evaluated after the mitral valve surgery and Cox-Maze procedure.

Inclusion Criteria:

• mitral valve disease;
• atrial fibrillation;
• mitral valve prosthetic replacement with concomitant Cox-Maze Procedure;
• 18-75 years of age;
• signed informed consent form.

Exclusion Criteria:

• mechanical valve replacement;
• repeated mitral valve surgery;
• coronary artery hemodynamically significant stenoses;
• ventricular arrhythmias;
• creatinine clearance <50 ml/min;
• HAS-BLED score >3;
• previous stroke or transient ischemic attack;
• liver diseases;
• neoplasia;
• pregnancy;
• simultaneous antiplatelet therapy;
• allergic reactions on Dabigatran or Warfarin;
• cognitive disorders.