Abstract
Amyloidosis is a heterogeneous group of diseases caused by the extracellular deposition of amyloid insoluble fibrils in multiple organs, resulting in various clinical manifestations. Cardiac amyloidosis (CA) occurs mainly in primary light-chain (AL) amyloidosis, hereditary transthyretin (ATTRv) amyloidosis and senile or wild-type transthyretin (ATTRwt) amyloidosis. Knowing that myocardial uptake at bone scintigraphy is an essential step in the ATTR-CA diagnostic algorithm, the level of awareness among nuclear medicine physicians (NMPs) using bone tracer scintigraphy is of great importance. The objective of the study was to evaluate NMPs’ awareness of scintigraphy with bisphosphonates for the detection of CA. We conducted an online survey among NMPs from Romania to assess their current awareness and state of knowledge of nuclear techniques used in CA. Among the total 65 Romanian NMPs, 35 (53%) responded to this questionnaire. Approximately three-quarters of participants (74%) found a diffuse accumulation of bisphosphonates in the heart on scintigraphy performed for bone pathology as an incidental discovery. Detection of myocardial uptake of 99mTc-labeled bisphosphonates on scintigraphy suggests CA-AL for 3% of participants and for 9% of respondents, the appearance is of uncertain cardiac amyloidosis, while 5% of participants observed cardiac uptake but did not report it as CA. Even if more than half of those who responded to this survey (54%) found abnormal cardiac uptake and interpreted it as CA-ATTR, only 14% contacted the referring physician to draw attention to the incidental discovery to refer the patient to a specialist in rare genetic cardiomyopathy. Regarding the knowledge about the categories of bisphosphonates recommended in the diagnosis of CA-ATTR, 54% answered inadequately that methylene diphosphonate (MDP) could be used. Romanian nuclear physicians are partially familiar with CA diagnosis by scintigraphy, but its diagnostic potential and standardization, recommended radiotracers and acquisition times and interpretation algorithms are known in varying proportions. Therefore, there is a need to enhance knowledge through continuing medical education programs in order to standardize the protocols for the acquisition, processing and interpretation of bisphosphonate scintigraphy for the detection of cardiac ATTR amyloidosis.
Highlights
Amyloidosis is a disease produced by the deposition of specific amyloid fibril proteins in different organs and tissues
Of the 35 survey participants, 85% practiced in the 3 largest Romanian university centers: 45% in the country’s capital (Bucharest), 28% from Iasi and 11% from Cluj
Each month, the number of patients investigated by conventional nuclear medicine techniques exceeds 150, falling within the range of 101–150, between 51–100, and under 50 (22% of nuclear medicine physicians (NMPs)) (Figure 1A)
Summary
Amyloidosis is a disease produced by the deposition of specific amyloid fibril proteins in different organs and tissues. Amyloid is recognized microscopically by its amorphous structure, an affinity for the Congo red dye and its increased birefringence under polarized light. According to the International Society of Amyloidosis Nomenclature Committee, the number of mature proteins responsible for amyloidosis is 18 proteins for systemic amyloidosis and 22 for localized forms; even some proteins can appear as systemic and localized amyloid deposits [1]. Of the 36 human amyloid fibrillar proteins currently discovered, only 9 can involve the myocardium and cause significant heart disease. More than 98% of amyloid cardiomyopathies are due to light chain monoclonal immunoglobulins (AL) and fibrilar transthyretin (ATTR). Other types of cardiac involvement (AApoAI, AApoAII, AApoAIV, Aβ2M, AFib, AGel) and cardiac amyloidosis secondary to chronic inflammatory and infectious diseases (AA) are very rare in medical practice [1,2]
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