A multicentre cross-sectional cohort study to assess the difference in bioprosthetic micro-calcification activity, detected with 18F-NaF PET-CT, as early marker of transcatheter valve degeneration, between patients with vs. without subclinical leaflet thrombosis at five years after TAVI; and between patients with intra-annular vs. supra-annular TAVI prostheses.

Subclinical leaflet thrombosis (SCLT) occurs frequently after TAVI and has been associated with an increased risk of valve dysfunction. A persistent form of SCLT may lead to thrombus calcification and valve degeneration and increase the long-term risk of symptomatic bioprosthetic valve deterioration. Intra-annular in comparison to supra-annular TAVI valves have been associated with a higher risk of SCLT and valve thrombosis. Intra-annular valves may create larger neo-sinuses and flow stagnation zones, which favour local thrombogenicity. Whether different prosthesis types lead to a higher degree of transcatheter valve calcification and degeneration is currently unexplored. Recently, 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) has emerged as a non-invasive modality capable of imaging bioprosthetic micro-calcification activity, which is an early and powerful predictor of valvular dysfunction and eventually valve failure. In the present study, we investigate for the first time, the differences in quantified bioprosthetic micro-calcification activity with 18F-NaF PET as early marker of transcatheter valve degeneration between patients with and without SCLT and between patients with intra-annular vs. supra-annular prostheses at five years after TAVI.

Inclusion Criteria:

• Successful TAVI with Sapien or CoreValve Evolut prosthesis about 5 years ago
• Able to undergo hybrid 18F-NaF PET-CT imaging and transthoracic echocardiography
• Written informed consent

Exclusion Criteria:

• Temporary or chronic oral anticoagulation use after TAVI
• Known severe renal insufficiency
• Known severe paravalvular regurgitation
• History of valve-in-valve procedure
• History of aortic valve re-intervention (including percutaneous paravalvular leak closure)

Patients who underwent TAVI about five years ago will be consecutively screened for eligibility from the ongoing, prospective, TAVI registries of the participating study sites and will be asked to undergo hybrid PET-CT imaging and transthoracic echocardiography.

Decided upon request