Bioprosthetic Aortic Valve Leaflet Thickening in the Evolut Low Risk Sub-Study

Background: Subclinical leaflet thrombosis has been reported after bioprosthetic aortic valve replacement, characterized using 4-dimensional computed tomographic imaging by hypoattenuated leaflet thickening (HALT) and reduced leaflet motion (RLM). The incidence and clinical implications of these findings remain unclear. Objectives: The aim of this study was to determine the frequency, predictors, and hemodynamic and clinical correlates of HALT and RLM after aortic bioprosthetic replacement. Methods: A prospective subset of patients not on oral anticoagulation enrolled in the Evolut Low Risk randomized trial underwent computed tomographic imaging 30 days and 1 year after transcatheter aortic valve replacement (TAVR) or surgery. The primary endpoint was the frequency of HALT at 30 days and 1 year, analyzed by an independent core laboratory using standardized definitions. Secondary endpoints included RLM, mean aortic gradient, and clinical events at 30 days and 1 year. Results: At 30 days, the frequency of HALT was 31 of 179 (17.3%) for TAVR and 23 of 139 (16.5%) for surgery; the frequency of RLM was 23 of 157 (14.6%) for TAVR and 19 of 133 (14.3%) for surgery. At 1 year, the frequency of HALT was 47 of 152 (30.9%) for TAVR and 33 of 116 (28.4%) for surgery; the frequency of RLM was 45 of 145 (31.0%) for TAVR and 30 of 111 (27.0%) for surgery. Aortic valve hemodynamic status was not influenced by the presence or severity of HALT or RLM at either time point. The rates of HALT and RLM were similar after the implantation of supra-annular, self-expanding transcatheter, or surgical bioprostheses. Conclusions: The presence of computed tomographic imaging abnormalities of aortic bioprostheses were frequent but dynamic in the first year after self-expanding transcatheter and surgical aortic valve replacement, but these findings did not correlate with aortic valve hemodynamic status after aortic valve replacement in patients at low risk for surgery.