Stroke Severity in Patients on Non-Vitamin K Antagonist Oral Anticoagulants with a Standard or Insufficient Dose

Background  The stroke severity or functional outcomes could differ because the efficacy of non-vitamin K antagonist oral anticoagulants (NOACs) could be different according to the dose. We investigated whether there was any difference in the stroke outcomes in patients with non-valvular atrial fibrillation (NVAF) by their prior medication status, including standard-dosed versus under-dosed NOACs. Materials and Methods  We enrolled 858 patients with acute ischaemic stroke with chronic NVAF admitted at six hospitals in Korea. We categorized their prior medication status as follows: (1) no anti-thrombotics ( n  = 219), (2) only anti-platelet ( n  = 347), (3) warfarin with a sub-therapeutic intensity ( n  = 185), (4) warfarin with a therapeutic intensity ( n  = 37), (5) under-dosed NOAC ( n  = 27) and (6) standard-dosed NOAC ( n  = 43). We compared the initial stroke severity between groups. Results  Among the 858 patients, the patients on standard-dosed NOACs had the lowest initial National Institute of Health Stroke Scale (NIHSS) score, followed by those on warfarin with a therapeutic intensity and those on only anti-platelet ( p B , –5.602; 95% confidence interval [CI], –8.636 to –2.568; p B , –3.588; 95% CI, –6.405 to –0.771; p  = 0.013), while there was no difference in the NIHSS score between the patients not taking any anti-thrombotics and those on warfarin with a sub-therapeutic intensity or under-dosed NOACs. Conclusion  Use of warfarin with a therapeutic intensity or standard-dosed NOACs was associated with a relatively mild stroke in the patients with NVAF.