ResearchAugust 31, 2026

A Peptide PET Scan Detected Cardiac Amyloidosis With 94% Sensitivity. The Hard Part Comes Next.

A phase 3 trial found 124I-evuzamitide PET/CT detected cardiac amyloidosis with 94% sensitivity. Here is what the scan can—and cannot—prove.

A radiolabeled peptide has cleared a serious diagnostic hurdle in one of cardiology’s easier diseases to miss.

In the prospective REVEAL trial, 124I-evuzamitide PET/CT detected cardiac amyloidosis with 94% sensitivity and 86% specificity. The study ran at 18 US centers, used blinded image readers, and was published online in JAMA on August 30, 2026.

Those numbers are strong enough to pay attention to. They are not strong enough to turn one scan into a final diagnosis.

That distinction matters because cardiac amyloidosis is not a single disease. It is a pattern of misfolded protein deposits in the heart, most commonly from transthyretin (ATTR) or immunoglobulin light chains (AL). The treatments for those two forms are fundamentally different. A tracer that can see amyloid across subtypes could simplify a difficult workup, but it cannot be allowed to blur the subtype question.

The news: a peptide that makes amyloid visible

Evuzamitide is not a drug meant to treat amyloidosis. It is a diagnostic peptide carrying the positron-emitting isotope iodine-124. After intravenous administration, PET/CT can show where the tracer accumulates.

Its target is unusually broad. Rather than binding only one amyloid precursor protein, the peptide is designed to recognize features shared by deposits across several amyloid types. The REVEAL design paper describes binding to highly sulfated heparan-sulfate structures associated with amyloid fibrils. Earlier laboratory work found that the p5+14 peptide behind evuzamitide preferentially binds highly charged heparin and heparan-sulfate molecules.

In plain English, the peptide is looking for part of amyloid’s local scaffolding, not simply the protein that started the deposit.

That approach could fill a genuine gap. Technetium-99m bone scintigraphy has transformed the noninvasive diagnosis of ATTR cardiac amyloidosis when it is used with the correct blood and urine testing. But bone-avid tracers do not directly bind amyloid, have limited utility in AL disease, and are not ideal tools for measuring whole-body burden or following deposits over time. Biopsy remains valuable when the picture is uncertain, though it is invasive and sampling can miss disease.

A pan-amyloid PET tracer offers a different proposition: look directly for deposits in the heart and, potentially, beyond it.

What REVEAL actually tested

REVEAL was a prospective, multicenter, single-group diagnostic study. Investigators enrolled 195 adults who were already being evaluated for suspected cardiac amyloidosis. People with an established diagnosis of cardiac or systemic amyloidosis were excluded.

The trial was built to reduce one common source of bias. Three physicians experienced in cardiac PET/CT reviewed the evuzamitide images without seeing the participants’ clinical data. Separately, three amyloidosis specialists adjudicated the diagnosis from the standard clinical workup without seeing the PET/CT result.

Participants received 1 mCi of 124I-evuzamitide intravenously. Imaging took place three to five hours later. They also received 130 mg of potassium iodide by mouth for three days, starting at least 30 minutes before the tracer, to reduce thyroid uptake of free radioiodine.

The JAMA abstract reports results for 170 participants. Their median age was 72; 75.3% were men. About 62% had New York Heart Association class II or III symptoms, meaning this was not a healthy screening population. These were patients in whom clinicians already had enough concern to begin an amyloidosis workup.

The headline results were:

Sensitivity: 94% (95% confidence interval, 85% to 98%)
Specificity: 86% (95% CI, 77% to 92%)
Positive predictive value: 85% (95% CI, 75% to 92%)
Negative predictive value: 94% (95% CI, 87% to 98%)

Sensitivity asks how often the scan was positive among people adjudicated to have cardiac amyloidosis. Specificity asks how often it was negative among those adjudicated not to have it. The high negative predictive value is encouraging for a rule-out role in this referral population: a negative result was rarely paired with an adjudicated diagnosis.

But predictive values are not fixed properties. They change with disease prevalence and patient selection. A test can perform one way in an amyloidosis center and differently in a low-risk general-cardiology population.

The rehook: 94% sensitivity still leaves two kinds of error

A 94% sensitivity result is easy to convert into “the scan finds amyloid.” The actual finding is narrower.

Some patients with disease will still have a negative scan. More visibly, an 86% specificity means false positives occurred. A positive image therefore cannot carry the whole diagnostic burden.

There is another issue: the comparison standard was expert adjudication using the conventional workup, not a mandatory heart biopsy for every participant. That is understandable. Requiring invasive biopsy from everyone in a diagnostic trial would be difficult and ethically questionable. It also means the reference standard is a carefully assembled clinical judgment rather than a perfect tissue answer.

The trial’s blinded design makes the evidence much stronger than an uncontrolled case series. Its single-group design still leaves open how evuzamitide should be positioned against, or added to, echocardiography, cardiac MRI, bone scintigraphy, monoclonal-protein testing, genetic testing, and biopsy.

The accessible abstract also reports 195 enrolled but 170 included in the analysis. Without the full participant-flow and safety tables, it would be wrong to invent reasons for the difference. The abstract calls the safety profile acceptable, but it does not provide event-level rates. “Acceptable” is all we can responsibly say from that source.

Why subtype still controls treatment

A pan-amyloid scan answers a location question: is there an imaging pattern consistent with amyloid in the heart? It does not automatically answer the precursor question: what protein is producing those deposits?

That is not administrative trivia. AL amyloidosis arises from abnormal light chains produced by a plasma-cell disorder and can progress quickly. ATTR amyloidosis comes from transthyretin, either the wild-type protein or an inherited variant. Therapies target those pathways differently.

Any future diagnostic pathway using evuzamitide would still need disciplined subtype testing. Monoclonal-protein evaluation cannot be skipped because a PET image looks persuasive. Genetic testing may still matter after ATTR is identified. Biopsy may still be necessary when tests disagree or more than one process is possible.

Think of evuzamitide as a potentially better map, not a molecular passport.

What earlier studies add—and what they do not

REVEAL did not appear from nowhere. Investigator studies have tested evuzamitide, previously called 124I-p5+14 or AT-01, in AL, ATTR, and rarer forms of amyloidosis.

One 2026 report included ten people with rare amyloidoses and 12 controls. All six participants who had cardiomyopathy showed visible myocardial uptake, while controls did not. Three of four amyloidosis participants without recognized cardiomyopathy also showed uptake despite negative findings on other imaging. That raises the possibility of earlier detection.

It is also a tiny exploratory study. Ten affected participants cannot establish screening performance, prognosis, or whether acting on an earlier signal improves health. REVEAL now supplies the larger multicenter diagnostic evidence, but the outcome question remains.

The mechanistic literature has conflicts worth knowing. Researchers involved in the peptide’s development have reported company ownership, patents, or support connected to Attralus. Industry ties do not invalidate data. They do increase the importance of independent replication, transparent reader training, and post-approval performance outside specialist centers.

The curiosity gap: seeing deposits is not the same as helping patients

A diagnostic test earns its place by changing decisions for the better.

The next studies should show where evuzamitide adds information that current pathways miss. Useful questions include whether it reduces unnecessary biopsy, shortens time to subtype-specific treatment, resolves equivocal scans, works consistently across hospitals, and detects AL disease early enough to alter outcomes.

Monitoring is another tempting use. Because the tracer directly targets amyloid-associated structures and can image outside the heart, it may eventually help quantify systemic burden or follow deposit clearance. REVEAL did not test that. Participants with established disease were excluded, and the study was designed around diagnosis, not treatment response.

Implementation may be just as important as accuracy. Iodine-124 production and distribution, PET scanner access, radiation exposure, thyroid blockade, delayed imaging, reader training, reimbursement, and regulatory status will all shape real-world use. A test can be scientifically elegant and still struggle if it is difficult to deliver at scale.

The Oria take

Evuzamitide is a useful reminder that peptide innovation is broader than injecting a signaling molecule and waiting for a therapeutic effect. Peptides can also act as precision delivery vehicles, carrying an imaging isotope to a biological structure that conventional tools struggle to see.

REVEAL is a meaningful result. It is prospective, multicenter, phase 3, and designed with independent blinded reading on both sides of the comparison. The reported sensitivity and negative predictive value support serious evaluation of evuzamitide as part of a cardiac-amyloidosis workup.

The responsible interpretation is narrower than the headline. This study does not show fewer deaths, fewer heart-failure admissions, faster treatment, or better quality of life. It does not show that a positive scan identifies AL versus ATTR. It does not establish population screening or treatment monitoring.

It shows that, in patients already suspected of cardiac amyloidosis, experienced readers using 124I-evuzamitide PET/CT could identify the condition with high diagnostic accuracy against an expert-adjudicated clinical standard. That is a strong step. The hard part now is proving where the scan changes care.

Sources

Evidence grade: B+. Strong prospective multicenter phase 3 diagnostic evidence with blinded image interpretation and blinded clinical adjudication. The grade stops short of A because the study was nonrandomized, did not use mandatory biopsy as a universal reference standard, and has not shown that adding the scan improves management or patient outcomes.

Medical disclaimer: This article is for educational purposes only and is not medical advice. 124I-evuzamitide is an investigational diagnostic radiotracer, not a treatment or a do-it-yourself peptide. Cardiac amyloidosis requires specialist evaluation because AL and ATTR disease follow different diagnostic and treatment pathways. Do not start, stop, or delay testing or treatment based on this article. Oria exists to make peptide research easier to understand, not to replace qualified medical care.

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