In this clinical trial, Rivaroxaban of standard dose (20mg) and reduced dose (15mg) will be administeted in non-valvular atrial fibrillation patients without severe renal dysfunction.

It is a randomized, open-label, and phase 4 clinical trial to compare and evaluate efficacy and safety of Rivaroxaban.

After obtaining informed consent to participate in this trial, screening is performed (Screening visit).

Screening includes baseline 12-lead electrocardiography and laboratory tests to exclude severe end-organ dysfunction (such as renal dysfunction, liver dysfunction, or anemia).

Baseline visits are available on the same day. After screening, subjects eligible for the trial will be randomly assigned (1:1 ratio) to Group 1 (15 mg of Rivaroxaban) or Group 2 (20 mg of Rivaroxaban) (Baseline visit).

The study drug (Rivaroxaban 15mg or 20mg daily) will be administered for 12 months.

During study period, a total of six visits (3,6,9,12 months) will be made, and follow-up test and outcome measurement will be done in each visit.

Inclusion Criteria:

1. adult men and women over 19 years of age when screening
2. A person whose atrial fibrillation has been confirmed by electrocardiogram during screening and baseline.
3. Anticoagulants for the prevention of stroke or systemic embolism For cases where medication is required, a person with a CHA2DS2-VASC score of 1 male/female 2 or more points (In case of one or more risk factors)
4. 4) CrCl (Creatinine Clearance) ≥50 ml/min
5. A person who voluntarily agrees in writing to this study

Exclusion Criteria:

1. Moderate mitral valve stenosis or mechanical artificial valve A person with a history of mechanical valve

2. Thyroid disease, terminal hypertrophy, brown cytoplasm, adrenal glands that affect the occurrence of atrial fibrillation A person accompanied by cortical disease, parathyroid disease, pancreatic disease, etc.

3. clinically significant bleeding (e.g., intracranial bleeding, gastrointestinal bleeding)

4. Clinical significance of liver disease related to blood coagulation disorder and Child Pugh B and C liver disease associated with the risk of bleeding

5. Patients with increased risk of bleeding due to the following conditions:

   • Gastrointestinal ulcer history within 6 months prior to random allocation

     • Intracranial or intracranial hemorrhage history within 6 months prior to random assignment

       • vascular abnormalities in the spinal cord or brain

         • History of brain, spinal cord or ophthalmic surgery within 30 days prior to random assignment

           ⑤ Brain or spinal cord injury within 6 months prior to random allocation

           ⑥ If you have esophageal varices or are suspected

           ⑦ Arteriovenous malformations

           ⑧ Vascular aneurysms

           ⑨ Patients with malignant tumors (Neoplasm) at high risk of bleeding

6. Stroke requiring combination of antiplatelet drugs when treating acute coronary syndrome or a patient with a history of transient ischemic attacks

7. Patients who are overreacting to the main or components of Rivaroxaban

8. Galactose intolerance, Lapp lactase deficiency, or glucose-galactose absorption a patient with genetic problems such as a disability

9. Patients with uncontrolled hypertension (systolic BP > 180 mm Hg or diastolic BP > 100 mm Hg)