Exploratory Study Evaluating the Relevance of [68Ga]Ga-FAPI-46 for Staging and Identifying Progressing Patients With Transthyretin Cardiac Amyloidosis

Transthyretin cardiac amyloidosis (ATTR-CM) is an infiltrative cardiomyopathy caused by amyloid fibril deposition, leading to heart failure and arrhythmias. Despite advances in diagnosis, the disease remains commonly unrecognized and presents heterogeneously. Recent therapies targeting transthyretin stabilization and gene silencing have improved outcomes, but current staging systems based on biological and functional markers have limited ability to guide treatment. Imaging techniques such as cardiac magnetic resonance (CMR) provide tissue characterization, but noninvasive molecular imaging of myocardial fibrotic activity remains limited. Positron emission tomography (PET) tracers targeting fibroblast activation protein (FAPI), labeled with gallium-68 (68Ga), offer a promising approach to detect and quantify fibroblast activity associated with myocardial remodeling. This study aims to evaluate \[68Ga\]Ga-FAPI PET imaging for staging ATTR-CM and distinguishing patients with disease progression under therapy. The investigators hypothesize that \[68Ga\]Ga-FAPI uptake reflects fibrotic activity correlating with disease severity and progression. If validated, \[68Ga\]Ga-FAPI PET could serve as a novel biomarker for improved staging and personalized strategies in ATTR-CM.