Rationale and design of ASSAF-K (A study of the safety and efficacy of anticoagulant therapy in the treatment of atrial fibrillation in Kanagawa)

BACKGROUND: Atrial fibrillation (AF) is one of the most prevalent cardiac arrhythmias associated with substantially increased risks of ischemic stroke and thromboembolism. Oral anticoagulants (OACs) are the cornerstone of AF management and effectively prevent AF-related stroke. As new non-vitamin K antagonist OACs (NOACs) have become available, the landscape of stroke prevention in AF has changed. However, there are considerable gaps between daily clinical practice and current guideline-based recommendations for anticoagulant therapy in Japan. Consequently, little is known about the real-world setting and the current use of NOACs, especially by practitioners in Japan. METHODS: We conducted a prospective, observational study in 3847 patients with AF who were enrolled in clinics and hospitals located in Kanagawa Prefecture from September 2013 through March 2015. The participating centers included practitioners (small clinics), medium-sized hospitals, and university hospitals. The primary endpoints were epidemiologic characteristics, status of treatment with anticoagulants and antiplatelet agents, outcomes, and adverse events, including cerebrovascular disease, bleeding, and death. RESULTS: The mean CHADS2 score was 1.81±1.27, the mean CHADS2-Vasc score was 3.02±1.58, and the mean HAS-BLED score was 2.23±1.06, respectively. The usage rate of warfarin was 44.2% overall, and the usage rate of NOACs was 33.5%. CONCLUSIONS: The results of the study are expected to serve as the basis for providing clinical practice guidance to healthcare institutions in Japan, with the ultimate goals of better characterizing the appropriate use of OACs and providing clinical decision support to physicians to facilitate the design of appropriate therapeutic strategies and the selection of anticoagulants for the management of AF.