Right ventricle involvement in cardiac transthyretin amyloidosis in SPECT/CT with [99mTc]Tc-DPD

Abstract

Abstract Funding Acknowledgements Type of funding sources: Other. Main funding source(s): Pfizer Research Grant (ID#57165999). Background Transthyretin amyloid (ATTR) cardiomyopathy continues to be considered a rare disease; however, it is now more frequently diagnosed, partly due to advances in imaging techniques. Application of hybrid technique single-photon emission computed tomography and computed tomography (SPECT/CT) provides greater anatomic resolution, enabling the assessment of regional cardiac involvement. Purpose The aim of this prospective study was assessment of right ventricle involvement in patients with ATTR in SPECT/CT with [99mTc]Tc 3,3-disphono-1,2-propanodicarboxylic acid (DPD). Methods We present data based on evaluation of 100 patients, including 28 (group 1) index patients with ATTR and 72 (group 2) first-degree relatives who were studied between June 2020 and January 2023. Study protocol included clinical data, free light chain blood immunoglobulins and urine immunofixation, transthoracic echocardiography (TTE) with global longitudinal strain (GLS) analysis, SPECT/CT with [99mTc]Tc-DPD, genetic testing by an amplicon-based next-generation TTR sequencing approach, and in selected cases cardiac or soft tissue biopsy. Results In group 1 there were 39% patients diagnosed with hereditary ATTR (ATTRm) and 61% with ATTR wild type (ATTRwt). There were detected following types of TTR variants - Phe53Leu, Ala101Val, Glu112Lys, Glu109Lys, Glu122Lys, Glu82Lys. Overall, 26% first-degree relatives were diagnosed with pathogenic TTR variant and 7% had positive SPECT/CT with [99mTc]Tc-DPD. In group 2 there was a significant predominance of Phe53Leu variant among carriers. Importantly, among patients with positive SPECT/CT with [99mTc]Tc-DPD 78% presented also right ventricle uptake. Overall, right ventricle involvement was present in 80% of patients with ATTRm and 76% of patients with ATTRwt who presented left ventricle uptake (p>0.05). Conclusions Right ventricle involvement in cardiac transthyretin amyloidosis can be assessed in SPECT/CT with [99mTc]Tc-DPD. In presented group 78% of patients who had cardiac tracer uptake presented as well right ventricle involvement. There were no statistically significant differences in rates between the ATTRwt and ATTRm groups (p>0.05). Assessment of right ventricle involvement in cardiac transthyretin amyloidosis in SPECT/CT may in future translate into further enhancement of disease evaluation and improving prognosis in the group of patients.