This trial will test the pharmacokinetic and pharmacodynamic characteristics of ascending doses of OPC-108459 in separate populations of paroxysmal and persistent AF subjects.~The trial will consist of two parts. Each part will evaluate two populations of subjects presenting for cardioversion in a hospital setting.~Cohorts of paroxysmal and persistent subjects may have their dose increased independently.
The purpose of Part 1 of this study is to determine the maximally tolerated dose of OPC-108459 in patients with paroxysmal and persistent atrial fibrillation (AF).~The purpose of Part 2 of this study is to determine potential efficacy of dose(s) of OPC-108459 for the treatment of paroxysmal and persistent atrial fibrillation.