An 87 year-old man has a history of cardiomyopathy (EF = 25-30%), atrial tachycardia, COPD, and CKD. Further investigation is warranted for possible cardiac amyloidosis.
There is intense PYP uptake within the myocardium, which is more than blood pool, consistent with transthyretin-related cardiac amyloidosis (TTR).
Transthyretin-related cardiac amyloidosis (TTR).
Amyloidosis is an infiltrative disease characterized by deposition of amyloid fibrils within the extracellular tissue of one or multiple organs. Cardiac amyloidosis is recognized as a common cause of restrictive cardiomyopathy and heart failure. There are two major types of cardiac amyloidosis: amyloid light-chain (AL), and transthyretin-related cardiac amyloidosis (TTR).
Prognosis and therapeutic options vary depending on the subtype. Endomyocardial biopsy with immunostaining is considered the gold standard, but advance imaging provides a non-invasive alternative. Recent data with 99mTc-phosphate derivatives (previously used as bone seeking radiotracers) selectively bind ATTR, but not AL subtype, and can differentiate subtypes with high diagnostic accuracy.
In the US, Tc 99m pyrophosphate ( 99mTc-PYP) imaging is used for the evaluation of TTR amyloidosis. PYP uptake in myocardium will diagnose TTR cardiac amyloidosis, while there won't be visualization of the myocardium on PYP study in cases with AL cardiac amiloidosis.
Amyloid light-chain (AL), and transthyretin-related cardiac amyloidosis (TTR).
Additional SPECT imaging may be needed to assist with grading of the uptake: 0- no uptake, 1- mild uptake is less than blood pool, 2- moderate uptake is equal to blood pool, 3- intense uptake is more than blood pool.
Role of imaging in the diagnosis and management of patients with cardiac amyloidosis: State of the art review and focus on emerging nuclear techniques. AlJaroudi, WA, Desai, MY, Tang, WHW and et al. J Nucl Cardiol 2014;21:271–83.
National patterns in imaging utilization for diagnosis of cardiac amyloidosis: A focus on Tc99m-pyrophosphate scintigraphy. Harb SC, Hag M, Flood K, and et al. J Nucl Cardiol. 2016 Mar 1-4.