Inclusion Criteria:

* Understands the study procedures and can give signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.
* Male or female ≥18 years of age.
* Is suspected of having cardiac amyloidosis and is undergoing or will undergo a diagnostic evaluation for cardiac amyloidosis (e.g., echocardiography, CMR, bone avid tracer cardiac SPECT, extracardiac or endomyocardial biopsy, etc.). Participants can be enrolled before or during their diagnostic evaluation for cardiac amyloidosis.
* Able to undergo PET/CT imaging as part of the study, including ability to lie supine for approximately 1 hour.
* For women of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive methods that result in a failure rate of \<1% per year during the treatment period and for at least 30 days after administration of I-124 evuzamitide.
* For men: agreement to remain abstinent or use contraceptive measures and agreement to refrain from donating sperm

Exclusion Criteria:

* Established diagnosis of cardiac amyloidosis.
* Established diagnosis of systemic amyloidosis (e.g., renal AL or ATTR peripheral neuropathy) without known cardiac involvement. Participants who are amyloid positive only with carpal tunnel tissue or laminectomy are allowed as long as they do not have other known organ involvement.
* Receiving therapy with an approved treatment (e.g., tafamadis) or in a clinical trial for treatment for ATTR cardiac amyloidosis at time of enrollment. For AL and ATTR: Patients may enter the screening period of a clinical trial for treatment after the ICF is signed and participant is enrolled in this trial but may not receive an experimental therapy until after the Day 30 safety follow-up visit in this trial.
* Is pregnant or breast-feeding.
* Is mentally or legally incapacitated, has significant emotional problems at the time of the study, or has a history of psychosis.
* Has a known allergy to potassium iodide.
* Receiving hemodialysis or peritoneal dialysis.
* eGFR less than 15mL/min/1.73m2.
* Myocardial infarction within three (3) months of screening.
* Has severe claustrophobia or any condition, medial or otherwise, that would prevent completion of the study assessments.
* Has any illness that, in the opinion of the investigator, might confound the results of the study or pose additional risk to the participant.
* Has received heparin or heparin analogs (e.g., enoxaparin, dalteparin, fondaparinux) within seven (7) days prior to I-124 evuzamitide administration.
* Known uncorrected thyroid disorders (other than mild elevation of thyroid stimulating hormone with normal T4).

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 7/29/2025. Questions regarding updates should be directed to the study team contact.