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

Abstract

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. We aimed to utilize 18F‑sodium fluoride (18F‑NaF) and 18F‑fluorodeoxyglucose (18F‑FDG) positron emission tomography/computed tomography (PET/CT) to evaluate early TAVI valve degeneration. In this prospective study with a prespecified follow‑up protocol, 71 TAVI patients underwent baseline transthoracic and transesophageal echocardiography, and PET/CT with 18F‑NaF and 18F‑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 18F‑NaF and 18F‑FDG PET/CT uptake at baseline and 24‑month follow‑up. 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 18F‑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 18F‑NaF maximal activity (inner, P = 0.17; outer, P = 0.57). Twenty‑four months post‑TAVI, an increase in 18F‑FDG uptake, indicative of inflammation, was observed in the valve, while the uptake of the calcification marker (18F‑NaF) remained stable. Theseobservations might suggest early stages of TAVI valve degeneration, although further investigation is required to confirm this interpretation.