Atrial Fibrillation

Inclusion Criteria

Japanese subjects with non-valvular AF who met all of the following criteria: 

 - Male subjects aged 20 years or older and postmenopausal female subjects
 - Subjects with persistent or paroxysmal non-valvular AF with >/=2 episodes before enrollment, at least 1 of which had been verified by ECG recording within 4 weeks before randomization 
 - Subjects who were at risk for stroke as follows: 
 - Subjects with at least one risk factor for thromboembolism (hypertension, diabetes mellitus, coronary artery disease, congestive heart failure).
 - Subjects aged 60 years old and above regardless of the existence of above risk factors.

Exclusion Criteria

- History or presence of stroke or transient ischemic attack. 
 - History of intracerebral hemorrhage.
 - History or presence of bleeding at randomization; intraocular or gastrointestinal bleeding within the last 6 months prior to randomization.