Nine‐year trend of oral anticoagulant use in patients with embolic stroke due to nonvalvular atrial fibrillation

BACKGROUND: Direct oral anticoagulants (DOACs) are increasingly used as an alternative to warfarin in patients with nonvalvular atrial fibrillation (NVAF). However, whether there is sufficient prescription of oral anticoagulants (OACs) to decrease the incidence of embolic stroke remains unclear. METHODS AND RESULTS: We conducted a retrospective observational study of patients hospitalized with ischemic stroke between January 1, 2010 and December 31, 2018. During the 8 years, the annual incidence ratio of embolic stroke to all ischemic strokes did not decrease over time (21‐33%) except for that in 2018. The proportion of OAC users did not also change over time (from 23% to 45% [overall 31%], P = .78). Among the OAC users, 19% patients were warfarin users, and 12% patients were DOAC users. In 73% of warfarin users, prothrombin time was subtherapeutic, whereas in 60% of DOAC users, the dose was adequately prescribed. OACs were prescribed more often in patients with high CHADS2 score than in those with low score (P = .01). The number of patients who had no medical history of a doctor visit before admission increased significantly in the recent period of 2015‐2018 (22% vs 8% in the previous period of 2010‐2014) (P = .01). CONCLUSIONS: The incidence of embolic stroke patients without OACs did not decrease over time, and OACs in patients with NVAF have not been sufficient, even in DOAC era. In recent years, the incidence of undiagnosed AF has increased. To prevent embolic stroke, a correct AF diagnosis beforehand is important.