Leaflet Thickening or Immobility Following Aortic Valve Replacement: Results from the Evolut Low Risk Sub-study

Abstract Background Subclinical leaflet thrombosis has been reported after bioprosthetic aortic valve replacement, characterized using 4-dimensional computed tomographic (CT) imaging by hypoattenuated leaflet thickening (HALT) and reduced leaflet motion (RLM). The incidence and clinical implications of these findings remain unclear. Objective This study sought 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 CT imaging 30 days and 1 year after 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 31/179 (17.3%) for TAVR and 23/139 (16.5%) for surgery; the frequency of RLM was 23/157 (14.6%) for TAVR and 19/133 (14.3%) for surgery. At 1 year, the frequency of HALT was 47/152 (30.9%) for TAVR and 33/116 (28.4%) for surgery; the frequency of RLM was 45/145 (31.0%) in TAVR and 30/111 (27.0%) for surgery. Aortic valve hemodynamics were not influenced by the presence or severity of HALT or RLM at either time point. The rates of HALT and RLM were similar after implantation of supraannular, self-expanding transcatheter or surgical bioprostheses. Conclusions We found that the presence of CT imaging abnormalities of aortic bioprostheses were frequent but dynamic in the first year after self-expanding transcatheter and surgical aortic valve replacement, but that these findings did not correlated with aortic valve hemodynamics after aortic valve replacement in patients at low risk for surgery.