ABC | Volume 114, Nº4, Suplement, April 2020

Case Report Silva et al. Transthyretin Amyloidosis - without the need for biopsy Arq Bras Cardiol 2020; 114(4Suppl.1):8-12 (95% CI, 0910–0.981). 10 The largest sample in this scenario was published by Gilmore et al. 2 with a sample of 1,217 patients with suspected amyloidosis, where about 360 patients had diagnostic confirmation made through pyrophosphate scintigraphy not requiring histopathological study. 2 In this multicenter study, in those patients without monoclonal gammopathy, nuclear medicine showed specificity and PPV close to 100%. For patients with clinical suspicion, echocardiogram or MRI suggesting the possibility of amyloidosis, there is a diagnostic sequence to be followed. 2,3,10 The flowchart begins with the request for immunofixation of proteins in the blood and urine in addition to assessment of light chains in the search for primary amyloidosis (AL). To move to the other stage of the investigation algorithm, it is essential that these initial Figure 2.1 Figure 2 – Myocardial scintigraphy with technetium-99m labelled pyrophosphate. 2.1) Counting ratio between the heart and the corresponding site in the right hemithorax = 1.8 (31/17 = 1.8). 2.2) Increased concentration of the radiotracer in the projection area of the heart against the costal margin, corresponding to score 3. Score >2 and counting ratio between the heart and the contralateral region >1.5 have a high probability of senile or hereditary transthyretin amyloidosis. 2.2 laboratory tests be negative. This is due to the existence of a portion of cases of AL with positive scintigraphy (possibly reaching 27% false positives). 2 If no monoclonal gammopathy is found, then the next step is to request 99mTc-pyrophosphate scintigraphy, for the purposes of, this time, identifying transthyretin deposits in the myocardium. 2,3,10 (Figure 3). With multimodality, we can identify and differentiate the types of amyloidosis early, with excellent accuracy and without the need for biopsies. 2,3,6-8,10 Conclusion Patients with clinical suspicion of amyloidosis, in the absence of monoclonal gammopathy, should continue the investigation with pyrophosphate scintigraphy, as it may 10