Photon-counting detector CT for prediction of valve dysfunction after transcatheter aortic valve implantation: Comparison with echocardiography

Background Noninvasive evaluation of suspected prosthetic valve dysfunction after transcatheter aortic valve implantation (TAVI) remains challenging because both anatomic and hemodynamic information are required for a conclusive diagnosis. Purpose To evaluate the diagnostic accuracy of hemodynamic parameters derived from time-resolved photon-counting detector (PCD)-CT for functional TAVI-assessment. Methods In this retrospective single-center study, consecutive post-TAVI PCD-CT examinations acquired between January 2023 and December 2025 were screened. After CT-based exclusion of cases with severe mitral regurgitation, systolic prosthetic valve orifice area was measured to calculate mean and maximum transvalvular pressure gradients ( P mean / P max ) from time-resolved left ventricular volumetry. Spearman correlation ( ρ ) and paired comparisons were performed with transthoracic echocardiography (TTE) as reference standard. Diagnostic performance of CT-derived P mean for identifying potential valve dysfunction was assessed. Results Seventy-one post-TAVI PCD-CT scans of 63 patients (median age, 77.0 [73.5–83.0] years; 37 women) were included. CT-derived parameters showed strong correlations and high agreement with their echocardiographic counterparts (orifice area : ρ = 0.73; P mean : ρ = 0.85; P max : ρ = 0.85; p < 0.001). There was no bias for orifice area or P mean , whereas CT-derived P max was higher than TTE-based P max (median difference, 4.4 mmHg; p < 0.001). CT-derived P mean showed high diagnostic performance for detection of potential valve dysfunction, with an area under the curve of 0.94, sensitivity/specificity of 88.9%/88.6%, accuracy of 88.7% and Youden index-derived optimal cutoff of 20.4 mmHg. Conclusion Time-resolved cardiac PCD-CT for post-TAVI imaging enables robust derivation of mean transvalvular pressure gradients that correlate strongly with echocardiography, show excellent diagnostic accuracy for screening of valve dysfunction and may expand the diagnostic value of cardiac CT toward functional assessment.