Anticoagulation Monotherapy vs Antiplatelet Monotherapy After Transcatheter Aortic Valve Implant: The ACASA-TAVI Randomized Clinical Trial.

Transcatheter aortic valve implant (TAVI) is increasingly being performed in younger and healthier patients with severe aortic valve stenosis. Antithrombotic therapy after TAVI is a key element of optimizing valve durability and clinical outcomes. To evaluate the safety and efficacy of a factor Xa inhibitor non-vitamin K antagonist oral anticoagulant (NOAC) monotherapy strategy vs an acetylsalicylic acid (ASA) monotherapy strategy after TAVI. Between December 2021 and June 2025, 360 participants between the ages of 65 and 80 years undergoing TAVI for severe aortic valve stenosis were enrolled in this prospective, randomized, open-label, blinded end point trial conducted at 3 Norwegian centers managing the majority of TAVI procedures nationally. The last patient completed follow-up on May 19, 2026. A total of 360 participants were randomly assigned (1:1) to receive 12 months of monotherapy with either NOAC (intervention) or ASA (control). A predefined co-primary end point strategy was chosen to address both efficacy and safety. The primary efficacy end point was TAVI valve leaflet thrombosis defined as the presence of hypoattenuated leaflet thickening (HALT) on blinded core laboratory 4-dimensional cardiac computed tomographic (CT) scan at 12 months. The primary safety end point was a composite of adjudicated Valve Academic Research Consortium 3 (VARC-3) bleeding events, thromboembolic events, and all-cause death at 12 months. Of the 360 participants randomized (mean age, 74.5 years [SD, 3.7]; 134 females [37%]), 336 completed the trial (168 in each group). The primary efficacy end point occurred in 27 participants (16.2%) allocated to the NOAC group and in 48 participants (28.6%) allocated to the ASA group (risk ratio, 0.55; 95% CI, 0.37 to 0.82, P = .004). The primary safety end point occurred in 13 participants (7.5%) in the NOAC group and in 19 participants (10.6%) in the ASA group (risk difference, -3.3%; 95% CI, -9.5% to 2.8%; P for noninferiority <.001). A strategy of NOAC monotherapy after TAVI reduced the incidence of HALT and was noninferior for bleeding, thromboembolic events, or death compared with acetylsalicylic acid monotherapy. These findings suggest that anticoagulation therapy can be beneficial after TAVI in selected patients. ClinicalTrials.gov Identifier: NCT05035277.