Transthyretin cardiac amyloidosis (ATTR-CA) causes progressive heart disease that is often overlooked. It harms the heart muscle because the unstable, unfurled amyloid proteins fold up into large pieces that get caught in between layers of heart tissue, causing amyloid deposits. The earlier it is detected, the better for the patient. There is a need to improve the early diagnosis of this disease because echocardiography (sonograms of the heart) and cardiac MRI are not useful enough for this. There is an X-ray of the heart using a compound called PYP that can detect amyloid deposits earlier than ultrasound images or clinical signs, but it's not clear how early it does so. Also, it can't detect amyloid deposits outside the heart, which causes lots of pain and suffering in people with this disease.~A new radiation compound, evuzamitide, has been shown to detect amyloidosis in the heart, liver, spleen, kidney, bone marrow and even in the peripheral nerves. So, the investigators want to use it to detect Transthyretin Amyloidosis:~In people who have a type of Amyloidosis which normally deposits in the heart, but in which PYP Scintigraphy didn't find it in there;~In people who have a type of Amyloidosis which normally deposits outside the heart, to see if this compound can detect it in the heart; and~In people who have proven Amyloid deposits in the heart, to see if this compound can detect them outside the heart.
This is a single center, prospective cohort study that is evaluating the ability of 124I-evuzamitide PET scanning to: (1) identify extra-cardiac amyloid deposits in patients with ATTRwt-CA and the Val122Ile variant; (2) to detect cardiac TTR amyloidosis in subjects with heart failure, increased wall thickness but only grade 1 Tc99PYP scans who are not currently diagnosed with ATTR-CA; and (3) to detect cardiac ATTR in allele carriers of TTR variants (Phe64Leu, late onset Val30Met) that are associated with cardiac amyloidosis but have PYP scans not diagnostic of ATTR-CM. If 124I-evuzamitide PET scanning is shown to be valuable in any of these three cohorts, it would address critical unmet needs regarding the diagnosis and extent of disease in ATTR-CM.~Consented eligible patients will undergo a single 124I-evuzamitide PET scan. Clinically available demographic, clinical and phenotypic data that is collected as part of routine clinical care will be used to characterize the type, severity, and stage of ATTR-CM.