MRI Findings of Intracranial Hemorrhages in ARCADIA-MRI: An Ancillary Study to the ARCADIA Trial

BACKGROUND AND PURPOSE: The ARCADIA-MRI study, an ancillary study to the randomized Atrial Cardiopathy and Antithrombotic Drugs in Prevention After Cryptogenic Stroke (ARCADIA) trial, reported that the risk of incident nonlacunar covert infarcts was lower in the apixaban group than in the aspirin group. This article presents the additional, prespecified, exploratory outcomes beyond the primary article, specifically examining the effect of apixaban on hemorrhagic lesions on MRI. MATERIALS AND METHODS: The ARCADIA-MRI study was conducted in conjunction with ARCADIA trial visits, with follow-up durations ranging from 4 months to 5.3 years (median, 27 months). It included randomized patients who were eligible for cognitive testing and lacked MRI contraindications. Two experienced raters, blinded to treatment assignments, independently evaluated the baseline and follow-up MRI scans. The radiologic end points of this analysis were incident intracranial hemorrhage (.10 mm), microbleeds (#10 mm), and superficial siderosis. RESULTS: MRI outcomes were compared between the 79 patients in the apixaban group and 95 in the aspirin group with both baseline and follow-up MRIs available. The treatment groups had similar baseline MRI findings. On the follow-up MRIs, the findings of incident bleeding events were similar between the treatment groups (all, P . .05): Intracranial hemorrhage occurred in 5.1% of patients in the apixaban group compared with 6.4% of patients in the aspirin group; microbleeds, 7.8% in the apixaban group and 10.8% in the aspirin group; and cortical superficial siderosis, in 7.7% of apixaban group and 12.9% in the aspirin group. CONCLUSIONS: In an exploratory analysis of the ARCADIA-MRI substudy, MRI findings of incident bleeding events were similar in patients randomized to receive apixaban and aspirin.