Non-Interventional Study on the Prevalence of Cardiac Amyloidosis in Patients With Higher-Grade Aortic Valve Stenosis - Evaluation Using Echocardiography, Computed Tomography, Tc99-SPECT/CT and Cardiac Magnetic Resonance Imaging (CMR)

Degenerative aortic stenosis (AS) is frequently accompanied by left ventricular hypertrophy and diastolic dysfunction, features that overlap with transthyretin (ATTR) cardiac amyloidosis. Because concomitant cardiac amyloidosis may adversely affect outcomes after transcatheter aortic valve implantation (TAVI), its early detection is clinically important. This prospective observational study aims to evaluate multimodal imaging biomarkers for the detection and characterization of cardiac amyloidosis in patients with severe AS undergoing TAVI evaluation. Clinically indicated technetium-99m phosphonate SPECT/CT and CT will be used to assess the presence and extent of cardiac amyloidosis, including quantitative measures of myocardial tracer uptake and extracellular volume. In patients with abnormal findings, cardiac magnetic resonance imaging (CMR) will be performed as an additional non-invasive imaging modality according to institutional clinical practice. The study will determine the prevalence of cardiac amyloidosis in this population and investigate the diagnostic and prognostic value of imaging-derived quantitative parameters. Standardized clinical follow-up at 6, 12, and 24 months will assess associations between imaging biomarkers and clinical outcomes. The study is observational and does not alter routine clinical management or diagnostic pathways.