ENSURE-AFA Prospective, Randomized, Open-Label Blinded Endpoint Evaluation (PROBE) Parallel Group Study Comparing Edoxaban (DU-176b) With Enoxaparin/Warfarin Followed by Warfarin Alone in Subjects Undergoing Planned Electrical Cardioversion of Nonvalvular Atrial Fibrillation

Study start date: March 25, 2014

Inclusion Criteria: * Has signed informed consent * Is older than minimum legal adult age (country specific) * Has had ongoing AF lasting at least 48 hrs but \<= 12 months (with or without valvular heart disease) * Has treatment plan that includes for electrical cardioversion * Has NVAF or other specific valvular heart diseases (eg, mitral valve prolapse, mitral valve regurgitation, and aortic valve disease) Exclusion Criteria: * Has AF that is transient or reversible * Has contraindicated condition, ie, conditions considered to be formal indication for conventional anticoagulation * Has a history of left atrial appendage (LAA) closure * Has a known thrombus in LAA, the left atrial, left ventricle or aorta - or an intracardial mass * Has had myocardial infarction (MI), stroke, acute coronary syndrome (ACS), or percutaneous coronary intervention (PCI) within the past 30 days * Has any contraindication to anticoagulant agents * Has had protocol-defined signs of bleeding or conditions associated with high risk of bleeding that would preclude participation * Is receiving, or plans to receive during the study period, dual antiplatelet therapy (DAPT) or invasive procedures (other than routine endoscopy) in which bleeding would be anticipated * Has received prohibited concomitant medication or therapy * Has had protocol-defined signs of bleeding or high * Has inadequate liver, kidney, and blood test results * Received any investigational drug or device within the past 30 days or plans to during the study period * Has reproductive potential and does not agree to take proper contraceptive measures * Has active cancer requiring chemotherapy/radiation/major surgery within the next 3 months * Has significant active concurrent medical illness or infection or life expectancy less than 6 months * In the opinion of the investigator, is unlikely to comply with the protocol or complete the study, has had drug or alcohol dependence within the past year, or has any other condition that might place the participant at increased risk of harm * Is a participant in the United States after January 2015 with creatinine clearance (CrCL) greater than 95 mL/minute