Anticoagulation Therapy and Event Risk in Japanese Patients with Atrial Fibrillation: Insight from the J-RHYTHM Registry

Since atrial fibrillation (AF) is a potent risk factor for thromboembolism, anticoagulation therapy is essential to prevent thromboembolism. Vitamin K antagonists (VKAs), mainly warfarin, have reportedly been able to reduce the risk of thromboembolism by 60%-70%. Although several non-VKA oral anticoagulants (NOACs) are currently available for the prevention of ischemic stroke and systemic embolism in patients with non-valvular AF (NVAF), VKAs remain to be used in patients with contraindication for NOACs such as severe renal impairment or valvular AF. The J-RHYTHM Registry was conducted as a nationwide prospective observational study to investigate the status of anticoagulation therapy with warfarin and the optimal anticoagulation therapy in Japanese patients with AF. A consecutive series of outpatients aged 20 years with AF of any type was recruited between January and July 2009, regardless of antithrombotic drug use. A total of 7,937 patients with AF were registered from 158 institutions. Patients were followed up for 2 years or until an event, such as thromboembolism, major hemorrhage, and all cause death, whichever occurred first. The main analysis in 7,406 patients with NVAFshowed the prothrombin time international normalized ratio (PT-INR) of 1.6-2.6 was safe and effective at preventing thromboembolic events in patients with NVAF,particularly patients aged 70 years. The PT-INRof 2.6-2.99 was also effective, but associated with a slightly increased risk of major hemorrhage. This AF registry has become a landmark study in Japan, and so far, more than 20 post hoc analyses have been published. In addition, the J-RHYTHM Registry 2 extended the follow-up period of the J-RHYTHM Registry for a total of 5 years, to investigate the effects of NOACs and the long-term effects of warfarin in Japanese patients with NVAF. This review overviews the J-RHYTHM Registry and the J-RHYTHM Registry 2.