[64Cu]FBP8 PET for Early Detection of Intracardiac Thrombus in Amyloid Cardiomyopathy

\[64Cu\]FBP8 is a novel copper-64 labeled molecular imaging probe that selectively binds to fibrin, the main constituent of human thrombi. In animal models, \[64Cu\]FBP8 has been shown to effectively detect pulmonary emboli, deep venous thromboses, and intracardiac thrombi. In a first-in-human study, \[64Cu\]FBP8 paired with simultaneous cardiac positron emission tomography (PET) and magnetic resonance imaging (MRI) accurately detected intracardiac thrombi (specifically, left atrial appendage \[LAA\] thrombi) in patients with atrial fibrillation (AF) with an accuracy of \>90% using transesophageal echocardiogram (TEE) as the reference standard. The investigators propose to study the value of \[64Cu\]FBP8 PET/MRI to detect intracardiac thrombi in patients with cardiac amyloidosis. This pilot study is designed to assess the value of \[64Cu\]FBP8 PET/MRI to detect intracardiac thrombi in twenty (20) patients with cardiac amyloidosis and atrial fibrillation (AF) or atrial flutter (AFL) compared to TEE. The primary hypothesis is that \[64Cu\]FBP8 PET/MRI can identify intracardiac thrombi in \>90% of subjects with confirmed intracardiac thrombi based on TEE. In secondary analyses, the investigators will seek to determine associations between intracardiac thrombi and left atrial function and left ventricular amyloid burden.