Risk-treatment paradox of anticoagulation therapy in atrial fibrillation.

include community, hospital, and emergency department settings.4–8 Of those we reported, the J-RHYTHM Registry,5,6 is a nationwide cohort study that enrolled 7,937 Japanese patients with AF (Figure 1). We found that nearly 90% of the patients were being treated with OACs because most of the patients were enrolled by cardiologists and electrophysiologists, and the major objective of this study was to determine the optimal anticoagulation levels for preventing thromboembolic and bleeding events. The study by Akao et al9 in this issue of the Journal is timely for bettering our understanding of the actual situation of antithrombotic therapies and outcomes in the Japanese AF population (Figure 1). The Fushimi AF Registry is a communitybased prospective survey of AF patients in an urban setting. The authors enrolled 3,282 AF patients and a 1-year follow-up was completed in 2,914 patients (a rate of nearly 90%). The trial fibrillation (AF) remains a global health issue, carrying a great burden of stroke and systemic thromboembolism.1 In 2050, it is estimated that there will be 1 million AF patients in Japan.2 Previous randomized trials and meta-analyses have provided very solid evidence in regard to the efficacy of oral anticoagulants (OACs) such as warfarin,3 but a significant limitation of randomized trials has been the strict inclusion/exclusion criteria for selecting a representative population of patients. Therefore, in addition to wellcontrolled randomized trials, we need add-on data sets, “clinical registries”, to examine whether these data findings apply more broadly over the patient populations.