Regression of Myocardial 99m Tc-DPD Uptake After Tafamidis Treatment of Cardiac Transthyretin Amyloidosis.

Cardiac transthyretin amyloidosis is an infiltrative cardiomyopathy with high mortality. To date, there are no specific biomarkers to directly assess disease activity and response to specific treatments. Our aim was to evaluate scintigraphic changes after treatment with the transthyretin stabilizer tafamidis. Methods: We included patients who had undergone ^99m Tc-3,3-diphosphono-1,2-propanodicarboxylic acid ( ^99m Tc-DPD) scintigraphy before tafamidis initiation and after at least 9 mo. Tracer activity was assessed visually and quantitatively as SUV _max Results: The study included 14 patients who were on tafamidis for 44 ± 14 mo. We observed regression of Perugini grade in 5 patients, unchanged grade in 9 patients, and regression of mean heart-to-contralateral-lung ratio ( P = 0.015) and SUV _max ( P = 0.005). There were no changes in N-terminal pro-B-type natriuretic peptide or echocardiographic measures. Conclusion: Treatment with tafamidis results in regression of myocardial ^99m Tc-DPD uptake. ^99m Tc-DPD scintigraphy may provide useful imaging biomarkers to assess response to treatment.
(© 2023 by the Society of Nuclear Medicine and Molecular Imaging.)