Short-Term Anticoagulant Therapy and Subclinical Leaflet Thickening in Transcatheter Aortic Valves: The NOTION-4 Trial.

BACKGROUND: Following transcatheter aortic valve replacement (TAVR), subclinical leaflet thrombosis-visualized on cardiac computed tomography (CT) as hypoattenuated leaflet thickening (HALT)-is common and might be associated with thromboembolic events. OBJECTIVES: The NOTION-4 trial investigates different antithrombotic treatment strategies for the prevention of HALT. METHODS: NOTION-4 was a randomized controlled trial enrolling patients without an indication for oral anticoagulation shortly after successful TAVR. Patients were randomized to lifelong single antiplatelet therapy (SAPT) or 3 months of direct oral anticoagulant (DOAC) therapy followed by lifelong SAPT (DOAC-3m). The primary endpoint was HALT prevalence at 12 months. The trial was powered for superiority of the experimental strategy. RESULTS: Of 352 patients randomized 1:1, 5 were screen failures or withdrew consent, leaving 176 in the SAPT group and 171 in the DOAC-3m group. At 3 months, HALT was observed in 31.8% of patients receiving SAPT compared with 12.1% of those receiving DOAC-3m. At 1 year, HALT occurred in 32.2% of SAPT patients and 28.3% of DOAC-3m patients with available CT scans (risk difference: -3.9%; 95% CI: -14.4% to 6.6%; P = 0.54). The combined risk of all-cause mortality, stroke, or major/life-threatening bleeding at 12 months was 2.3% in the SAPT group vs 8.2% in the DOAC-3m group (risk difference: 5.9%; 95% CI: 1.2% to 10.6%). CONCLUSIONS: Among TAVR patients without an indication for oral anticoagulation, 3 months of DOAC therapy significantly reduced the prevalence of HALT at 3 months compared with SAPT; however, this effect was attenuated by 9 months after discontinuation of DOAC therapy. (The Nordic Aortic Valve Intervention Trial 4 [NOTION-4]; NCT06449469).