A strategy of anticoagulation monotherapy after transcatheter aortic valve implantation (TAVI) reduced subclinical leaflet thrombosis and was noninferior for bleeding, thromboembolic events, and death compared with antiplatelet monotherapy, according to results of the ACASA-TAVI trial presented at ESC Congress 2026 and published simultaneously in JAMA.1
Frequently Asked Questions
What did the ACASA-TAVI trial find about NOAC monotherapy after TAVI?
NOAC monotherapy reduced subclinical leaflet thrombosis by nearly half compared with aspirin monotherapy (16.2% vs 28.6%) and was noninferior for the composite safety endpoint of bleeding, thromboembolic events, and death.
Was NOAC monotherapy associated with more bleeding than aspirin after TAVI?
No. Overall bleeding rates were low and numerically higher with aspirin, and life-threatening or lethal bleeding events occurred only in the aspirin group.
Does this trial change antithrombotic guidelines after TAVI?
Current guidelines discourage routine anticoagulation without an independent indication; investigators say ACASA-TAVI provides new evidence, which could inform future guideline updates, particularly for younger, lower-risk TAVI patients.
“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,” said Øyvind Lie, MD, PhD, MSc, principal investigator Oslo University Hospital Rikshospitalet, Norway. “However, there is a gap in our knowledge with regards to the optimal antithrombotic therapy after TAVI.”2
ACASA-TAVI trial design and primary efficacy findings
ACASA-TAVI was an investigator-initiated, multicenter, prospective, randomized, open-label, blinded-endpoint trial conducted at 3 centers in Norway, enrolling patients aged 65 to 80 years after successful TAVI without an independent indication for anticoagulation or antiplatelet therapy. Of 360 patients randomized 1:1 to 12 months of monotherapy with a factor Xa inhibitor non-vitamin K antagonist oral anticoagulant (NOAC; apixaban, edoxaban, or rivaroxaban) or acetylsalicylic acid (ASA), 336 completed the trial. Mean age was 74.5 years, and 37% were female.1
The primary efficacy endpoint, hypoattenuated leaflet thickening (HALT) on blinded core-laboratory cardiac CT at 12 months, occurred in 27 of 167 patients (16.2%) in the NOAC group versus 48 of 168 patients (28.6%) in the ASA group (risk ratio, 0.55; 95% CI, 0.37-0.82; P = .004). More severe HALT (grade 2 or higher) was substantially more prevalent in the ASA group, while grade 1 HALT rates were similar between groups.1
Safety noninferiority and mortality signal with NOAC monotherapy
The co-primary safety endpoint, a composite of Valve Academic Research Consortium 3 bleeding events, thromboembolic events, and all-cause death at 12 months, occurred in 13 patients (7.5%) in the NOAC group versus 19 patients (10.6%) in the ASA group, meeting the prespecified noninferiority margin (risk difference, -3.3%; 95% CI, -9.5% to 2.8%; P for noninferiority < .001). Two patients in the NOAC group died during the trial compared with 10 in the ASA group (risk difference, -4.4%; 95% CI, -8.9% to -0.6%), a finding investigators characterized as exploratory given the trial was not powered for individual safety components. Life-threatening (VARC-3 type 3) and lethal (type 4) bleeding events occurred only in the ASA group, and overall bleeding rates were low and numerically higher with ASA.1
“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,” said Lie.2
Investigators noted the recommendation against routine anticoagulation after TAVI has rested on trials evaluating combinations of anticoagulants and antiplatelet agents rather than head-to-head monotherapy comparisons, and positioned ACASA-TAVI as addressing this evidence gap directly for younger, lower-risk TAVI populations where valve durability is a key long-term concern.1
The trial investigators cautioned findings may not extrapolate to patients older than 80 years, and noted the open-label design could have influenced medication adherence and adverse-event reporting.
“We were able to show substantial reductions in signs of subclinical leaflet thrombosis with NOAC monotherapy, without compromising safety,” said Lie. “Results from the ACASA-TAVI trial may establish a new antithrombotic treatment paradigm after TAVI and could be used to inform future guidelines.”2
References
Dodgson CS, Herstad J, Kløve SF, et al. Anticoagulation monotherapy vs antiplatelet monotherapy after transcatheter aortic valve implant: the ACASA-TAVI randomized clinical trial. JAMA. Published online August 30, 2026. doi:10.1001/jama.2026.17036
European Society of Cardiology. What is the best approach to reduce clots on the new heart valve after TAVI? Published August 30, 2026. Accessed August 30, 2026.
