Key result
Tafamidis and spironolactone reduce myocardial and increase mammary 99mTc-PYP uptake in ATTRwt-CM.
Why the study?
99mTc-PYP scintigraphy shows physiological and pathological tracer accumulation in myocardium and extracardiac tissues including breasts in ATTRwt cardiomyopathy, but changes before and after treatment are not well described.
Case Report (n=1)
Spironolactone-induced gynecomastia can cause increased mammary and reduced myocardial 99mTc-PYP uptake in patients with ATTRwt-CM, which may confound scintigraphy interpretation.
Spironolactone may confound 99mTc-PYP scintigraphy via gynecomastia in ATTRwt-CM; case report leaves open generalizability and need for validation.
Scintigraphy using 99mTc-PYP as a bone-avid radiotracer reveals physiological and pathologic accumulation of the tracer in the extraosseous tissues and organs-including the breasts-in addition to the bones. 99mTc-PYP scintigraphy also reveals deposits of wild-type amyloid transthyretin (ATTRwt) in the myocardium and extracardiac sites, such as subcutaneous fat, skeletal trunk muscles, and alimentary tract, of patients with ATTRwt cardiomyopathy (CM). We describe an 87-year-old man with ATTRwt-CM in whom myocardial 99mTc-PYP uptake was reduced and mammary tracer uptake was increased due to gynecomastia after treatment with a disease-modifying drug for ATTRwt-CM, tafamidis, and heart failure medications, including spironolactone.
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Takahashi et al. (2026) conducted a case report in ATTRwt cardiomyopathy (n=1). Tafamidis and spironolactone was evaluated. Treatment with tafamidis and spironolactone in an 87-year-old man with ATTRwt-CM led to reduced myocardial 99mTc-PYP uptake and increased mammary tracer uptake due to gynecomastia.
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