Technetium-99m pyrophosphate cardiac SPECT in endomyocardial biopsy negative cardiac amyloidosis

Cardiac amyloidosis is an under-appreciated cause of heart failure. Establishing a diagnosis is important because traditional heart failure treatment regimens can worsen left ventricular failure in this disease. Endomyocardial biopsy is the gold standard for diagnosis; however, scintigraphy with radiolabeled phosphate derivatives and cardiac magnetic resonance imaging have been shown to have high sensitivity and specificity in diagnosing cardiac amyloidosis. Furthermore, cardiac scintigraphy can reliably differentiate amyloid subtypes. We present a case of transthyretin-related cardiac amyloidosis with a negative endomyocardial biopsy but positive 99m-technetium pyrophosphate single photon emission computed tomography scan and cardiac magnetic resonance imaging. We discuss the utility of 99m-technetium pyrophosphate imaging in cardiac amyloidosis and the role of single photon emission computed tomography. Finally, we review the several forms of cardiac amyloidosis and how they pertain to cardiac scintigraphy.