A new analysis from the AZALEA-TIMI 71 trial has found that the novel factor XI inhibitor abelacimab significantly reduces bleeding compared with rivaroxaban in patients with atrial fibrillation, even in those also taking antiplatelet therapy (APT). Factor XI inhibition may provide a safer anticoagulation strategy for patients requiring combination antithrombotic treatment. The results were published in the Circulation.

The study enrolled 1,287 patients (median age 74 years, 44% women) between March and December 2021, randomizing them to monthly subcutaneous abelacimab (90 mg or 150 mg) or daily oral rivaroxaban. About 25% of the patients were on APT at baseline, including aspirin only (15.5%), a P2Y12 inhibitor only (7.5%), or dual therapy (1.6%).

In the rivaroxaban group, major or clinically relevant non-major bleeding occurred at a rate of 10.6 events per 100 patient-years with APT versus 7.7 without rivaroxaban treatment. In contrast, abelacimab-treated patients had much lower bleeding rates, ranging from 2.5 to 3.5 events per 100 patient-years with APT and 2.7 to 3.1 without abelacimab treatment.

Compared with rivaroxaban, both abelacimab doses reduced bleeding risk by about 70% in patients with APT and by 60%–66% in those without. Absolute risk reductions were greater in those on APT, reaching up to 8.1 events per 100 patient-years.