The goal of this clinical trial is to learn if Rebamipide effective in gastroprotection in patients with atrial fibrillation who are treated with Direct Oral Anticoagulants (DOACs). Another point is to compare efficacy of Rebamipide and of its combination with Pantoprazole with efficacy of Pantoprazole only.

Participants will:

Take one of three variants of treatments for up to 24 weeks. Visits to the clinic wil take place for screening and then every 8 weeks.

The study enrolls 210 patients with atrial fibrillation (AF) and a moderate or high risk of thromboembolic complications (>=1 point in men and >=2 points in women according to the CHA2DS2VASc scale), who receives direct oral anticoagulants (DOACs) or has indication to their dministration for prevention of thromboembolic complications and in the same time has indication for gastroprotection.

The study includes a screening period (to confirm selection criteria) and a treatment period (maximum 24 weeks), that consists of 4 visits:

• Visit 1 (randomization),
• Visit 2 and 3 - follow up,
• Visit 4 - end of study. Patients will be randomized to one of three treatment groups in a 1:1:1 ratio.
• Group Rebamipide, receiving standard therapy and rebamipide 300 mg per day
• Group Pantoprazole , receiving standard therapy and pantoprazole 40 mg per day
• Group Combination of Rebamipide and Pantoprazole, receiving standard therapy, rebamipide 300 mg per day and pantoprazole 40 mg per day Standard therapy in the study refers to the use of DOAC in accordance with applicable clinical guidelines.

Physical examination, blood pressure/heart rate measurement, Adverse Events (AEs) control, concomitant medications and compliance assessment will be performed every visit. An Esophagogastroduodenoscopy (EGD) with H. pylori detection, Lanza score assessment, GOS questionnaire, and laboratory tests (blood and stool tests) will be performed on screening and visit 4.

Inclusion Criteria:

• Men and women from 18 till 80 years old

• Patients with atrial fibrillation (AF) and a moderate or high risk of thromboembolic complications (>=1 point in men and >=2 points in women according to the CHA2DS2VASc scale), receiving DOAC (rivaroxaban, apixaban or dabigatran) for the prevention of thromboembolic complications

• The following indications for the use of rebamipide and/or pantoprazole:

  • Chronic gastritis with high acidity in combination with gastroesophageal reflux disease
  • Peptic ulcer if negative test for H. pylori
  • Сhronic erosive gastritis
  • Need for

Exclusion Criteria:

• Refusal to participate in the study
• Participation in any other clinical trial or taking study drugs within 3 months before enrollment;
• Contraindications to study procedures
• Participation in the study is unsafe according to the investigator opinion.
• Admission of prohibited medication
• Pregnancy and lactation, as well as the inability to use reliable contraception in women of childbearing age
• Peptic ulcer in the acute stage
• Acute erosion on screening visit