The Role of Molecular Imaging in the Assessment of Cardiac Amyloidosis: State-of-the-Art

Abstract

Cardiac amyloidosis is a progressive infiltrative disease for which new treatments are now available. As therapy should be started as early as possible to avoid complications such as restrictive cardiomyopathy, arrhythmias and heart failure, a prompt and reliable diagnosis by means of non-invasive tests would be highly warranted. Electrocardiography, echocardiography and cardiac magnetic resonance imaging are all used in the evaluation of cardiac amyloidosis with varying diagnostic and prognostic accuracy, but none of these modalities can effectively differentiate the cardiac amyloid subtypes. We aim to highlight the most relevant findings in the literature of molecular imaging in the assessment of patients with cardiac amyloidosis and to underline future clinical perspective. We performed multiple searches using Pub-Med databases in order to find important original articles on the role of molecular imaging in the assessment of patients affected by CA. Several search terms were used, such as "cardiac amyloidosis"; "Light-chain amyloidosis"; "Transthyretin amyloid cardiomyopathy"; "bone scintigraphy"; "single photon emission tomography" or "SPECT"; "Positron emission tomography or PET", and "cardiac imaging". All radiopharmaceuticals tracing cardiac amyloidosis were also included. Several studies about the role of SPECT with bone-seeking tracer (47 articles) and innervation tracer (9 articles) in the work-up of CA, as well as new PET amyloid-binding (14 articles) and bone radiotracer (4 articles) have been reviewed and discussed. Molecular imaging represents a sensitive tool for early assessment of both amyloid burden and cardiac innervation, to differentiate between subtypes and to monitor disease burden, disease progression, and potential response to therapy.

Keywords: Cardiac amyloidosis; SPECT; bone scintigraphy; light-chain; positron emission tomography.; transthyretin amyloid cardiomyopathy.