Invasive pressure-volume loop and PET-MR phenotyping in transthyretin cardiac amyloidosis: a multimodal imaging case report.

Background: Cardiac amyloidosis (CA) is an under-recognized cause of heart failure in elderly patients. While diagnosis has traditionally relied on echocardiographic red flags and bone scintigraphy, novel tools may provide enhanced disease characterization. Case summary: We present the case of a 78-year-old man with progressive symptoms of heart failure who was diagnosed with wild-type transthyretin cardiac amyloidosis (ATTRwt-CM) through conventional and advanced multimodal imaging. Initial clues included a discordance between QRS voltages on electrocardiography and increased left ventricular wall thickness on echocardiography, along with signs of elevated filling pressures. Speckle-tracking echocardiography revealed impaired regional myocardial deformation, global function, and work energetics. Serum and urine immunofixation excluded light chain (AL) amyloidosis. DPD scintigraphy confirmed amyloid deposition with a characteristic distribution. Genetic testing ruled out hereditary variants. PET imaging demonstrated myocardial uptake suggestive of amyloid infiltration and microcalcification. Cardiac MR revealed elevated native T1 and extracellular volume fractions. Invasive pressure-volume loop assessment confirmed biventricular stiffness and impaired contractile reserve, despite clinical compensation at rest. These findings supported early initiation of Tafamidis in a minimally symptomatic patient. Discussion: This case highlights the role of advanced diagnostics in refining cardiac amyloidosis phenotyping and guiding individualized therapeutic decisions.