The Regional Scintigraphic DPD Uptake in Cardiac Transthyretin Amyloidosis.

Cardiac transthyretin (ATTR) amyloidosis is an infiltrative cardiomyopathy with an inexorably progressive clinical course and poor prognosis. The disease is caused by misfolding of the liver-derived precursor protein transthyretin as a result of an acquired wild-type variant (ATTRwt) or as a hereditary mutant variant (ATTRm). Application of single-photon emission computed tomography (SPECT) provides greater anatomic resolution, enabling the assessment of amyloid burden within individual left ventricle segments.

This study aims to describe the pattern of regional myocardial distribution of 3,3-diphosphono-1,2-propanedicarboxylic acid (DPD) SPECT uptake among patients with ATTRwt and ATTRm. It will investigate the clinical, biochemical and echocardiographic, including left ventricle longitudinal strain profile in ATTRwt and ATTRm. Moreover, we will evaluate the presence and extent of DPD cardiac uptake among asymptomatic ATTRm variants carriers.

This is a prospective multi-center observational study. The study, after obtaining prior written informed consent, will include consecutive patients who have Grade 1-3 cardiac DPD retention in scintigraphy. In addition, first-degree relatives of patients with ATTRm are going to be enrolled. Patients are going to undergo TTR gene sequencing to assess the presence of pathogenic variants associated with ATTRm. Both planar scintigraphy, SPECT and speckle-tracking echocardiography will be reviewed and interpreted using visual and quantitative approaches.

The collected data will be analyzed statistically to verify research hypotheses. Approval from the local Bioethical Committee will be obtained before carrying out the study. All procedures performed are going to be in accordance with the ethical standards of the 1964 Helsinki declaration and its later amendments, or comparable ethical standards.