Abstract 15706: Sub-Clinical Leaflet Thrombosis in Patients With Freestyle Root Replacement

IntroductionAortic Root and valve replacement using freestyle porcine stentless bioprosthesis provides superior geometry and hemodynamics, which could translate into low thrombogeneicity, obviating the need for anticoagulation. To date there has been no systematic studies of leaflet thrombosis.Methods173 patients underwent aortic root replacement with a Freestyle root in a single center from 2009 to 2017. 70 patients were screened for leaflet thrombosis using MSCT. Leaflet thrombosis was defined as reduced leaflet motion by 50% on time-resolved 4D MSCT associated with hypoattenuating leaflet thickening. Data on anticoagulation and clinical outcomes were collected.Results70 patients were examined with mean age of 35±5 years. 12 patients (17%) were on anticoagulation either for AF or for other valve replacement. Leaflet thrombosis was found in 15 patients (21%). The cumulative probability of leaflet thrombosis was 4±2% at 2 years, 14±4% at 3 years and increased to 35±8% at 5 years. There was a trend towards an association between an implanted Freestyle size>25 mm and the hazard of leaflet thrombosis (P=0.059). Thrombus occurred usually on NCC (73%), and less frequently on LCC (27%), 2 patients had thrombus on both NCC and LCC. (Figure 1) No thrombus occurred on RCC. No patient had stroke or thromboembolic events, and the mean gradient across the valve was 10±3 mmHg with no significant incompetence.ConclusionThis study has documented the occurrence of subclinical leaflet thrombosis in patients with Freestyle aortic root replacement. This can develop both early and late after replacement. The influence of these findings on long term valve function, stroke and response to the anticoagulation needs urgent investigations.Figure 1showed hypoattenuating opacities on 2D MSCT (maximum intensity projection of gray-scale image) and volume-rendered MSCT (color images) of freestyle valves during diastole and systole. The hypoattenuating lesions always involve the leaflet base and extend to the center of the frame. Leaflets with reduced motion are visible as wedge-shaped or semilunar opacities in both systole and diastole. (A) thrombus was in NCC. (B) thrombus was in LCC.