Key takeaways

• More younger patients are now receiving transcatheter aortic valve implantation (TAVI), making it increasingly important that replacement heart valves are durable.

• In the ACASA-TAVI trial, people who took a non-vitamin K antagonist oral anticoagulant (NOAC) had fewer signs of early blood clots around their replacement valve than those who took the usual treatment (acetylsalicylic acid, also known as aspirin).

• The use of NOACs was not associated with bleeding concerns and safety was comparable between NOACs and acetylsalicylic acid.

• NOAC monotherapy could represent an effective and safe antithrombotic approach for patients after TAVI.

Munich, Germany – 30 August 2026: After transcatheter aortic valve implantation (TAVI), anticoagulation reduced imaging signs of clot formation on the new valve compared with antiplatelet therapy, without compromising safety. This was the main finding of the ACASA-TAVI trial presented in a Hot Line session today at ESC Congress 2026¹ and published simultaneously in JAMA.

The use of TAVI for patients with symptomatic severe aortic valve stenosis has increased exponentially since the first successful intervention two decades ago. The durability of the bioprosthetic valves used in TAVI is now becoming increasingly important as indications expand to include younger patients with longer expected lifespans.

Principal Investigator of the ACASA-TAVI trial, Doctor Øyvind Lie from Oslo University Hospital Rikshospitalet, Norway, said: “Thrombus formation on the leaflets of implanted bioprosthetic valves is a potentially preventable cause of early valve dysfunction and has been linked to increased risk of stroke and death.² However, there is a gap in our knowledge with regards to the optimal antithrombotic therapy after TAVI.” Current recommendations are either an antiplatelet agent, such as acetylsalicylic acid (ASA; aspirin) or a non-vitamin K antagonist oral anticoagulant (NOAC) but only if an independent indication for anticoagulation exists.³ “Although anticoagulation after TAVI has been evaluated in randomised trials, these studies assessed combinations of anticoagulants and antiplatelet agents. The ACASA-TAVI trial was designed to be a head-to-head comparison of NOAC monotherapy and ASA monotherapy, assessing subclinical leaflet thrombosis and safety in patients without an indication for anticoagulation,” explained Doctor Lie.

This investigator-initiated trial was conducted across three hospitals in Norway. In total, 360 consecutive patients aged 65−80 years who had undergone successful TAVI were included. Participants were randomised (1:1) to 12 months of a NOAC (apixaban, edoxaban or rivaroxaban) or ASA (or clopidogrel if intolerant or if used prior to the trial). The primary efficacy endpoint was the occurrence of hypo-attenuated leaflet thickening, a measure of subclinical leaflet thrombosis, assessed by cardiac computed tomography at 12 months. The primary safety endpoint was a composite of Valve Academic Research Consortium-3 bleeding events, thromboembolic events and all-cause death at 12 months.

The researchers found that the occurrence of imaging signs of leaflet thrombosis was significantly reduced by 45% in patients who received NOACs compared with ASA at 12 months (17.2% vs. 32.6%; risk ratio 0.55; 95% confidence interval [CI] 0.37 to 0.82; p=0.004).

The safety profile of NOACs was also good, with noninferiority demonstrated between NOAC and ASA groups for the primary safety endpoint (7.5% vs. 10.6%; risk difference −3.3; 95% CI −9.5% to 2.8%; p for noninferiority <0.001). Two patients assigned to NOACs and 10 patients assigned to ASA died during the study. The overall number of bleeding events was low, but numerically higher in patients treated with ASA compared with NOACs, particularly for more severe bleeding events. “Clinicians may perceive the bleeding risk of anticoagulants to be higher than that of antiplatelet agents, but we found in this study that life-threatening and lethal bleeding occurred only in patients in the ASA group,” noted Doctor Lie.

Concluding, he said: “We were able to show substantial reductions in signs of subclinical leaflet thrombosis with NOAC monotherapy, without compromising safety. Results from the ACASA-TAVI trial may establish a new antithrombotic treatment paradigm after TAVI and could be used to inform future guidelines. We will continue to follow the trial participants over a 10-year period, further investigating the impact of NOAC monotherapy on valve durability and clinical outcomes.”

ENDS