A Trial to Determine the Safety, Pharmacokinetics, and Efficacy of OPC-108459 Administered as a Single Intravenous Dose to Patients With Paroxysmal or Persistent Atrial Fibrillation (AF)

Inclusion Criteria: * Japanese * Male or female age 20 to 85 years, inclusive (at the time of informed consent) * Patients diagnosed with recent or new onset of paroxysmal AF (3 hours to 7 days since the onset) or persistent AF (8 to 30 days since the onset) at time of randomization (prior to Investigational Medicinal Product \[IMP\] administration). Review of the patient's medical records and the judgment of the investigator or sub-investigator must be documented in the source documents to establish the date and duration of the most recent onset of AF. * Patients who are receiving treatment according to the "Guidelines for Pharmacotherapy of Atrial Fibrillation (JCS 2008)" at time of screening and predosing examinations or who have a low risk of thromboembolic potential specified as follows: * AF lasting less than 48 hours, OR * For AF lasting for 48 hours or longer: * Patients receiving warfarin therapy for whom at least 3 weeks have elapsed since achieving an international normalized ratio (INR) of 2.0 to 3.0 (1.6 to 2.6 for patients age 70 years or older) or in whom no thrombus in the atrial main body or appendage is observed by transesophageal echocardiography (TEE) within 24 hours before IMP administration * Patients in whom no thrombus in the atrial main body or appendage is observed by TEE within 24 hours before IMP administration if they have not undergone antithrombotic therapy or if they have undergone antithrombotic therapy (including a new oral ant…