Abstract DP358: Age Subgroup Analysis of Anticoagulant Monotherapy Versus Combination Therapy in Patients With Ischemic Stroke and Nonvalvular Atrial Fibrillation - ATIS-NVAF trial -

Background: In the ATIS-NVAF randomized trial, anticoagulant monotherapy was compared with combination therapy (oral anticoagulant plus antiplatelet) in patients with ischemic stroke or transient ischemic attack (TIA), nonvalvular atrial fibrillation (NVAF), and atherosclerotic cardiovascular disease (ASCVD). Primary analysis showed no added ischemic benefit with combination therapy but increased bleeding. We aimed to determine whether treatment effects differed by age subgroup. Methods: Patients were enrolled 8–360 days after an index stroke or TIA and randomized 1:1 to anticoagulant monotherapy or combination therapy. Subgroups were younger (0.4). For major bleeding, no interaction was seen (p=0.233), and risk of major plus clinically relevant non-major bleeding tended to increase in both groups (HR 2.25 younger, 2.02 elderly). For ICH, HRs were 0.12 (0.00–1.21; p=0.076) in younger and 2.12 (0.60–8.90; p=0.245) in elderly, with significant interaction (p=0.033). Conclusions: Combination therapy did not reduce ischemic outcomes compared with anticoagulant monotherapy in either age subgroup. However, a significant interaction for ICH suggested decreased risk in younger but increased risk in elderly. These findings highlight the need for individualized antithrombotic strategies, especially in older patients.