Wild-Type Transthyretin Amyloidosis With 99mTc-PYP Uptake in the Extracardiac Soft Tissues But Not in the Myocardium

Wild-type transthyretin amyloid (ATTRwt) deposits in most organs, mainly the heart, ligaments, and tenosynovium. Orthopedic diseases due to ATTRwt deposits often precede overt ATTRwt cardiomyopathy. 99mTc-PYP scintigraphy is highly sensitive in detecting myocardial and extracardiac ATTRwt deposits. However, there are few reports of extracardiac ATTRwt deposits before myocardial deposits confirmed by imaging modalities. We report a case of atrial fibrillation-related heart failure in which 99mTc-PYP scintigraphy showed tracer uptake in extracardiac soft tissues but not in the myocardium, and a biopsy of soft tissues with tracer uptake confirmed ATTRwt deposits. 99mTc-PYP scintigraphy can image extracardiac ATTRwt deposits before myocardial deposits.