Effectiveness of Nonvitamin K Antagonist Oral Anticoagulants and Warfarin for Preventing Further Cerebral Microbleeds in Acute Ischemic Stroke Patients with Nonvalvular Atrial Fibrillation and At Least One Microbleed: CMB-NOW Multisite Pilot Trial

Abstract Background Nonvitamin K antagonist oral anticoagulants (NOACs) are considered superior, or at least noninferior, to warfarin in preventing stroke or systemic embolism in patients with nonvalvular atrial fibrillation. Here, we recruited acute ischemic stroke patients with nonvalvular atrial fibrillation and at least one cerebral microbleed (CMB), and evaluated the proportion of patients who had an increased number of CMBs (%) after receiving anticoagulant therapy with NOACs or with warfarin for 12 months. Methods This was a multicenter, prospective, observational cohort study at 20 centers, conducted between 2015 and 2017, in which we recruited 85 patients with at least one CMB detected by 1.5T magnetic resonance imaging (T2*WI) at baseline, who received NOACs or warfarin for at least 12 months. We compared the proportions of patients with increased numbers of CMBs in the NOACs and warfarin treatment groups. Results The proportions of patients with increased numbers of CMBs at month 12 of treatment were 28.6% and 66.7% in the NOACs and warfarin groups, respectively. The new CMBs showed no specific regional localization in either group. In the NOACs and warfarin groups, physicians prescribed lower-than-standard dosing in 13.3% and 50% of the cases, respectively. The administration of reduced doses at physicians’ discretion did not appear to alter the incidence of new CMBs. Discussion This is the first evidence to suggest efficacy of NOACs for preventing further CMBs in patients with at least one CMB, although no statistical evaluation was carried out.