¹⁸F-fluorodeoxyglucose and ¹⁸F-sodium fluoride positron emission tomography imaging in assessing early stages of aortic valve degeneration after transcatheter aortic valve implantation

Introduction Transcatheter aortic valve implantation (TAVI) is a standard treatment for severe aortic stenosis, primarily in elderly patients. With an increasing number of procedures and younger patients, understanding the valve degeneration and its risk factors becomes crucial. Objectives We aimed to utilize F-18-sodium fluoride (F-18-NaF) and F-18-fluorodeoxyglucose (F-18-FDG) positron emission tomography / computed tomography (PET/ CT) to evaluate early TAVI valve degeneration. Patients and methods In this prospective study with a prespecified follow-up protocol, 71 TAVI patients underwent baseline transthoracic and transesophageal echocardiography, and PET/CT with F-18-NaF and F-18-FDG. Of these, 31 patients completed 24-month control examinations, while the others were lost to mortality and the COVID-19 pandemic. We measured PET tracer activity and compared F-18-NaF and F-18-FDG PET/ CT uptake at baseline and 24-month follow-up. Results PET/CT and echocardiography data were analyzed for 31 of the 71 enrolled TAVI patients at a median age of 84 years (interquartile range, 80-86). After TAVI, an improvement in the valve function was observed. During follow-up, the valve function remained stable. PET/CT demonstrated an increase in F-18-FDG maximal uptake in the inner (tissue-to-background ratio, P = 0.009) and outer (P = 0.01) sides of the TAVI valve stent, but no difference in F-18-NaF maximal activity ( inner, P = 0.17; outer, P = 0.57). Conclusions Twenty-four months post-TAVI, an increase in F-18-FDG uptake, indicative of inflammation, was observed in the valve, while the uptake of the calcification marker (F-18-NaF) remained stable. These observations might suggest early stages of TAVI valve degeneration, although further investigation is required to confirm this interpretation.