MRI findings intracranial hemorrhages in ARCADIAMRI: an ancillary study to the ARCADIA trial

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 non-lacunar covert infarcts was lower in the apixaban group than the aspirin group. This paper presents the additional, prespecified, exploratory outcomes beyond the primary paper, specifically examining the effect of apixaban on hemorrhagic lesions on MRI. 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 radiological endpoints of this analysis were incident intracerebral hemorrhages (>10 mm), microbleeds (≤10 mm), and superficial siderosis. 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 all similar between the treatment groups (all p > 0.05): intracerebral hemorrhages occurred in 5.1% of patients in the apixaban group compared to 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. 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. ARCADIA= atrial cardiopathy and antithrombotic drugs in prevention after cryptogenic stroke; AF= atrial fibrillation; DOAC= direct-acting oral anticoagulants; ICH =intracerebral hemorrhage; NT-proBNP= N-terminal pro-B-type natriuretic peptide; NAVIGATE ESUS=Rivaroxaban versus aspirin for prevention of covert brain infarcts in patients with embolic stroke of undetermined source; RE-SPECT ESUS=Randomized, Double-Blind, Evaluation in Secondary Stroke Prevention Comparing the Efficacy and Safety of the Oral Thrombin Inhibitor Dabigatran Etexilate versus Acetylsalicylic Acid in Patients with Embolic Stroke of Undetermined Source; COMPASS =Cardiovascular Outcomes for People Using Anticoagulation Strategies; ATTICUS study =The Apixaban for Treatment of Embolic Stroke of Undetermined Source.