Inclusion Criteria- Non valvular atrial fibrillation (AF)
- Indication for long-term Vitamin-K antagonist (VKA) therapy based on the presence of previous ischemic stroke, transient ischemic attack (TIA) or systemic embolism and/or at least two of the following risk factors: hypertension requiring drug treatment, moderately or severely impaired left ventricular function and/or congestive heart failure, age > or = 75 years, diabetes mellitus.
Main exclusion Criteria:
- Indication for VKA other than AF
- Stroke or TIA within previous 5 days
- Transient AF caused by a reversible disorder
- Planned major surgery/trauma or cardioversion within 30 days
- INR > 3 at baseline
- Active bleeding or high risk of bleeding
- Uncontrolled hypertension
- Pregnancy or childbearing potential without proper contraceptive measures or breast feeding.