Myocardial uptake of radionuclide in patients undergoing skeletal scintigraphy: Case series

Two main types of cardiac amyloidosis (CA) exist, as a result of either aberrant plasma cell production of misfolded monoclonal light chains, known as immunoglobulin light chain amyloidosis (AL), or production of disintegrated and misfolded transthyretin (TTR) proteins by the liver, also called transthyretin amyloidosis (ATTR). Non-invasive diagnostics (cardiac uptake on diphosphonate scintigraphy, Perugini score 2 or 3) have gained prominence in modern cardiology in correlation with the negative findings of free light chains in serum and the results of negative immunofixation in serum and urine. Additionally, criteria related to echocardiography or cardiac magnetic resonance are necessary for establishing a diagnosis. A total of 3.063 99mTc-MDP bone scintigrams were analyzed between August 2018 and March 2023, of which Perugini score 1 was validated in 13 patients, Perugini score 2 in 10 patients and Perugini score 3 in 1 patient. From our experience, we could observe that cardiac uptake can be verified in daily clinical practice and that is meaningful for monitoring patients with ATTR-cardiomyopathy (ATTR-CM). Although the sample size is not large, the importance of the study lies in the fact that it involves patients whose findings have been incidentally verified. If patients are selected according to clinical characteristics, the number of positive findings may potentially increase. Our study aimes to raise awareness among physicians of various specialties about the significance of the diagnostic algorithm for infiltrative cardiomyopathies. This is to ensure early diagnosis of this problem and initiation of treatment in the earliest stages when the therapeutic effect is most optimal. Such an approach would yield benefits for both patients and the entire healthcare system. A meticulous diagnostic and therapeutic approach is therefore fundamental for improving clinical outcomes in patients with ATTR-CM, including careful attention to specific TTR genetic variants and long-term follow-up.