Role of ^99mTc-DPD scintigraphy in diagnosis and prognosis of hereditary transthyretin-related cardiac amyloidosis

Objectives: In a cohort of patients with hereditary transthyretin-related amyloidosis (ATTR), we aimed to assess the role of ^99mTc-3,3- diphosphono-1,2-propanodicarboxylic acid ( ^99mTc-DPD) in detecting myocardial amyloid infiltration across a wide spectrum of cardiac involvement and in predicting major adverse cardiac events (MACE). Background: Hereditary transthyretin-related amyloidosis is a challenging and underdiagnosed condition where both early diagnosis and prognosis remain problematic. Methods: We evaluated 63 patients with ATTR: 40 with and 23 without echocardiographically diagnosed amyloidotic cardiomyopathy (AC). Myocardial uptake of ^99mTc-DPD scintigraphy was semiquantitatively and visually assessed at 5 min and 3 h. Results: All patients with AC showed moderate-to-severe myocardial tracer uptake (i.e., visual score 12 mm in combination with H/WB >7.5 was associated with the highest event rate. Conclusions: In ATTR, ^99mTc-DPD scintigraphy can identify myocardial infiltration across a wide spectrum of morphologic/functional cardiac involvement, allowing an early diagnosis of the disease (even before the appearance of echocardiographic abnormalities). The ^99mTc-DPD myocardial uptake is a prognostic determinant of "cardiac" outcome in ATTR, either alone or in combination with LV wall thickness.