How is suspected transthyretin-related cardiac amyloidosis diagnosed? Role 99mTc-HDMP scintigraphy: a substitute for biopsy?

Abstract

Cardiac amyloidosis (CA) is characterized by extracellular deposition of protein-derived fibrils and lead to heart failure. Gold standard for its etiological diagnosis is endomyocardial biopsy and laboratory tests, both high-cost and invasive procedures. Technetium- 99m hydroxymethylene diphosphonate (99mTc-HMDP) scintigraphy is important tool for defining CA, specifically transthyretin subtype (ATTR). From July 2020 to February 2021, we retrospectively analyzed 18 pts [14 males, 4 females; aged 32-86y] with suspected ATTR, underwent to scintigraphy 150 min after iv administration of 740 MBq 99mTc-HMDP.Myocardial uptake was assessed optically based on Perugini Score (0- 3). Biopsy confirmed diagnosis. Intense (Score 3) and moderate (Score 2) myocardial uptake verified in 8 patients by 99mTc-HDMP scintigraphy, was consistent with ATTR suspect. In 10 patient's cardiac radiotracer uptake was absent (Score 0) avoiding biopsy. Our data indicate a 99mTc-HDMP scintigraphy key role in the early diagnosis but even more in the exclusion of patients with ATTR subtype, optimizing the management of pts who do not require high costs and invasive procedures.