Figure 3.

Diagnostic algorithm in patients with suspect cardiac amyloidosis and evidence of cardiac uptake on 99mTc-DPD scintigraphy (or equivalent bone scanning). While with a ^99mTcDPD grade 2 or 3 the absence of a monoclonal protein in serum/urine is diagnostic of ATTR cardiomyopathy, its presence requires more investigations, and in particular the differential diagnosis between ATTR and AL amyloidosis via endomyocardial biopsy in patients older than 50 years, that are at higher risk of ATTR. A ^99mTcDPD grade 1 in absence of a monoclonal protein in serum/urine still requires an endomyocardial biopsy to understand the nature of the underlying cardiomyopathy/amyloidosis.