Once used to diagnose myocardial infarction, technetium-99m pyrophosphate (Tc 99m PYP) imaging may be reborn as an alternative to biopsy for diagnosing cardiac transthyretin (ATTR) amyloidosis in some patients. Interest in the test is growing as new therapies show promise in late-stage clinical trials, suggesting possibilities for treating the under-recognized condition.
Clinicians have known about cardiac amyloidosis for several decades. They have understood there are two main types of the disease: cardiac transthyretin (ATTR) amyloidosis, which is caused by amyloid deposits made up of the TTR protein, and light-chain (AL) amyloidosis, which is an acquired plasma cell disorder.
Patients diagnosed with AL amyloidosis have been able to receive chemotherapy or stem-cell transplantation, both of which could be life-saving. But those diagnosed with ATTR amyloidosis had no treatment options. That limitation, plus the risks associated with performing biopsies on heart tissue to diagnose cardiac amyloid, dampened interest for comprehensive screening for a condition believed to be rare and untreatable.