Half-dose rivaroxaban vs antiplatelet therapy for preventing silent cerebral embolism after left atrial appendage occlusion: the HALO-SCE trial.

BACKGROUND AND AIMS: The optimal long-term antithrombotic strategy after left atrial appendage occlusion (LAAO) remains undetermined. The present study aimed to investigate whether half-dose rivaroxaban (10 mg daily) could better reduce silent cerebral embolic lesions (SCEs) and preserve cognitive function compared to antiplatelet therapy after successful LAAO. METHODS: In this investigator-initiated, prospective, multicenter, randomized controlled trial, patients with successful LAAO confirmed 45 days post-procedure were assigned 1:1 to half-dose rivaroxaban or antiplatelet therapy group. Diffusion-weighted magnetic resonance imaging and cognitive assessments were repeated at 90, 180 and 365 days after LAAO. The primary outcome was the patient-level incidence of any newly detected SCE during follow-up. Secondary outcomes included cognitive trajectories, SCE burden, and a composite of all-cause mortality, clinical thromboembolic events and major bleeding. RESULTS: Between December 2022 and February 2025, 164 patients were randomized. The patient-level incidence of new SCEs was significantly lower in the half-dose rivaroxaban group than in the antiplatelet therapy group (10/82 [12.2%] vs. 26/82 [31.7%]; P = 0.005). At 365 days, model-derived between-group differences favored the half-dose rivaroxaban group for both Mini-Mental State Examination (2.56; 95% confidence interval [CI] 1.11-4.01; P < 0.001) and Montreal Cognitive Assessment (2.67; 95% CI 1.07-4.26; P = 0.001) scores. The composite clinical outcome occurred in 2.4% of the half-dose rivaroxaban group vs. 11.0% of the antiplatelet therapy group (P = 0.057). CONCLUSIONS: In patients eligible for oral anticoagulation after successful LAAO, rivaroxaban 10 mg daily significantly reduced SCEs and better maintained cognitive function compared with antiplatelet therapy, with numerically fewer composite clinical events.