The relationship between stroke severity and prior direct oral anticoagulant therapy in patients with acute ischaemic stroke and non-valvular atrial fibrillation

Background and purpose Anticoagulant treatment with a vitamin K antagonist (VKA) has been reported to reduce stroke severity when patients with atrial fibrillation (AF) suffer acute ischaemic stroke (AIS). Direct oral anticoagulant (DOAC) therapy also has the potential to reduce the initial severity of AIS. However, the effect of DOAC therapy on the severity of AIS is not well known. The aim of the present study was to investigate the effect of DOACs on initial stroke severity in patients with AIS and non-valvular AF. Methods From March 2011 to July 2016, consecutive patients with AIS having non-valvular AF were recruited. The effects of prior DOAC treatment on severity were assessed by multivariate logistic regression analyses. Results A total of 484 patients [208 women; median age 79 (interquartile range, 71–85) years; National Institutes of Health Stroke Scale (NIHSS) score 9 (interquartile range, 3–20)] were enrolled. Of these, 352 (73%) were on no anticoagulant medication, 54 (11%) were undertreated with a VKA, 35 (7%) were sufficiently treated (admission prothrombin time–international normalized ratio: ≥2.0 for patients <70 years old and ≥1.6 for ≥70 years old) with a VKA and 43 (9%) were on a DOAC. The initial NIHSS score (median 10 in patients with no anticoagulation, 13 in undertreated VKA, 7 in sufficient VKA and 6 in DOAC, P = 0.018) was different among the groups. Multivariate analysis showed that DOAC was independently and negatively associated with severe (initial NIHSS score ≥ 10) stroke (odds ratio, 0.39; P = 0.041), compared with no anticoagulant therapy. Conclusions Direct oral anticoagulant treatment prior to the event should reduce initial stroke severity in patients with AIS and non-valvular AF.