Aims: Four-dimensional volume-rendered computed tomography (4DCT) has demonstrated instances of hypo-attenuating leaflet thickening (HALT) with or without hypo-attenuation affecting motion (HAM) after transcatheter and surgical aortic valve implantation (TAVI, SAVR). The temporal pattern of evolution of these phenomena is uncertain.

Methods and results: The SAVORY registry enrolled patients treated by TAVI (n = 75) or SAVR (n = 30) with two 4DCT scans fully interpretable for HALT and HAM as well as unchanged anti-thrombotic medication between the scans. Logistic regression analysis was performed to examine the evolution of HALT and HAM while accounting for demographic and baseline variables, timing of both CT scans, valve type and antithrombotic therapy. The analysis population consisted of 84 patients, in whom first and second CT scans were performed at 140 ± 152 days and 298 ± 141 days after valve implantation, respectively. Hypo-attenuating leaflet thickening was noted in 32 patients (38.1%), with HAM in 17 (20.2%). Both findings were dynamic, showing progression in 13 (15.5%) and regression and 9 (10.7%) patients. Compared with antiplatelet therapy, progression was less likely among patients on oral anticoagulation with vitamin-K antagonists or non-VKA oral anticoagulants (odds ratio: 0.014, P = 0.036). Maintenance on chronic oral anticoagulation was not a significant predictor of regression. These findings were similar for both transcatheter and surgical bioprosthetic aortic valves. No patients developed symptoms of valve dysfunction and leaflet thickening was not clearly associated with any clinical events.

Conclusions: Subclinical leaflet thrombosis is a common finding after TAVI and SAVR, and may progress from normal leaflet over HALT to the more severe HAM. The phenomenon can develop and regress at variable intervals after valve implantation. Anticoagulants may have a protective effect against the development of HALT, but HALT can also regress without anticoagulation therapy.

Registered at ClinicalTrials.gov: NCT02426307.