A Phase III clinical trial published in JAMA has found that a novel PET/CT radiotracer, iodine-124-evuzamitide, demonstrated high sensitivity and specificity for diagnosing cardiac amyloidosis, a rare and serious condition in which abnormal protein deposits accumulate in the heart, leading to progressive heart failure and arrhythmias.
Cardiac amyloidosis results from the deposition of misfolded proteins, most commonly transthyretin (ATTR) or immunoglobulin light chain (AL), in the myocardium, causing the heart walls to thicken and impairing cardiac function. Diagnosis is challenging because, outside of heart biopsy, no single non-invasive test can definitively confirm or exclude the condition. Current practice relies on a combination of nuclear medicine scans, echocardiography, cardiac MRI, and blood tests, which can still yield equivocal results.
Evuzamitide works by binding directly to amyloid fibrils regardless of their protein subtype, making it potentially applicable across different forms of cardiac and systemic amyloidosis. The trial enrolled 170 patients with suspected cardiac amyloidosis across 18 medical centres in the United States. Participants received a single intravenous dose of evuzamitide, with PET/CT imaging performed three to five hours later. Oral potassium iodide was administered concurrently to protect the thyroid.
The radiotracer achieved 94% sensitivity and 86% specificity across both ATTR and light chain amyloidosis subtypes, with comparable performance between the two forms. The researchers suggest evuzamitide may be particularly valuable in cases where standard imaging is inconclusive, providing diagnostic clarity without requiring biopsy.
Further research is needed to determine how evuzamitide should be integrated into existing diagnostic pathways and whether it may eventually become a standard component of cardiac amyloidosis workup.
Source: Dorbala S et al. 124I-Evuzamitide Positron Emission Tomography/Computed Tomography for Diagnosing Cardiac Amyloidosis. JAMA (2026). DOI: 10.1001/jama.2026.17361
