Incidence, Predictors, and Outcomes of Subclinical Valve Thrombosis After TAVR in Bicuspid Aortic Valve Stenosis.

Subclinical valve thrombosis, radiographically defined as hypo-attenuated leaflet thickening (HALT) on computed tomography angiography (CTA), may impact bioprosthetic valve durability and outcomes following transcatheter aortic valve replacement (TAVR). This study aimed to evaluate HALT incidence, identify distinct predictors in bicuspid (BAV) versus tricuspid (TAV) aortic valves, and assess its clinical and hemodynamic implications. A total of 508 patients (285 BAV, 223 TAV) were included in the analysis. HALT incidence was comparable between groups (13.6% [39/285] vs 13.0% [29/223], p = 0.823), though severity and predictors differed. TAV patients showed greater leaflet thickening (2.7 ± 1.5 mm vs 1.9 ± 1.1 mm, p = 0.04). In BAV, independent predictors included elevated D-dimer, deeper transcatheter heart valve (THV) implantation, higher THV nadir eccentricity index, and asymmetric leaflet expansion. In TAV, predictors included elevated D-dimer, lower early peak transvalvular velocity, and asymmetric leaflet expansion. HALT was not associated with 1-year transvalvular gradients or left ventricular ejection fraction in either group. Clinically, HALT was associated with higher cerebrovascular event rates (2.9% vs 0.5%, p = 0.031) and an increased risk of major adverse cardiac and cerebrovascular events (MACCE) (13.2% vs 5.7%, p = 0.036; HR = 2.24). In conclusion, HALT incidence is comparable between BAV and TAV patients, but predictors differ: THV expansion characteristics are dominant in BAV, while hemodynamic parameters prevail in TAV. Elevated D-dimer is a consistent predictor across both groups. Although HALT does not affect mid-term hemodynamics, its potential association with higher MACCE risk warrants long-term surveillance and individualized management strategies.