Extremely Severe Aortic Stenosis Mimicking Cardiac Amyloidosis on Multimodality Imaging

Cardiac amyloidosis is increasingly recognized in older patients with severe aortic stenosis, yet advanced pressure-overload remodeling can produce overlapping imaging features that confound noninvasive diagnosis.

A 70-year-old woman presented with progressive exertional dyspnea and markedly elevated cardiac biomarkers. Transthoracic echocardiography revealed extremely severe calcific aortic stenosis, increased left ventricular wall thickness, and severely reduced global longitudinal strain. Cardiac magnetic resonance imaging demonstrated elevated native T1 and extracellular volume with late gadolinium enhancement, and cardiac amyloid radionuclide imaging showed Perugini grade 1 uptake. Despite clinical suspicion of cardiac amyloidosis, noninvasive findings remained inconclusive. The patient underwent surgical aortic valve replacement with intraoperative myocardial biopsy, which demonstrated cardiomyocyte hypertrophy and interstitial fibrosis without amyloid deposition, consistent with advanced pressure-overload remodeling rather than infiltrative disease.

Extremely severe aortic stenosis can mimic cardiac amyloidosis across multiple imaging modalities. Histologic confirmation remains essential when noninvasive findings are discordant or inconclusive.

Severe aortic stenosis may closely mimic cardiac amyloidosis on multimodality imaging. Histological confirmation can be decisive in resolving diagnostic uncertainty.