The relationship between chronic expansion of self-expandable valves and paravalvular leakage in transcatheter aortic valve implantation

Paravalvular leakage (PVL) is a clinical concern in transcatheter aortic valve implantation (TAVI). Although PVL has been reported to gradually decrease after self-expandable valves (SEVs) implantation, the mechanism remains unclear. Furthermore, while gradual expansion of SEVs has been documented, studies assessing their morphological changes during the chronic phase are lacking. This study aims to evaluate whether SEVs expansion occurs during follow-up and if this expansion correlates with a reduction in PVL. We included 60 patients who underwent TAVI using SEVs (Evolut PRO/PRO+/FX) from October 2020 to August 2024. Morphological findings of SEVs were assessed using computed tomography (CT), and PVL was evaluated at discharge and chronic phase post-TAVI. PVL was graded on a five-point scale via transthoracic echocardiography, and the area ratio, defined as the ratio of the basal area of the implanted SEVs to that of phantom valves measured by CT, served as the index of SEVs expansion. Chronic expansion of SEVs was observed in all cases, with the area ratio increasing from 0.59 at discharge to 0.64 at the follow-up (P < 0.05). Among the 60 patients, 44 exhibited mild or greater PVL, with 17 showing improvement at the chronic phase. The degree of valve expansion (area ratio at chronic phase/area ratio at discharge) was significantly greater in the PVL improvement group compared to the non-improvement group (1.11 vs. 1.06, P < 0.05). This study demonstrates that SEVs expand during the chronic phase after TAVI, which could contribute to the reduction of PVL.