[^99mTc]Tc-DPD SPECT/CT evaluation of right and left ventricular involvement in cardiac transthyretin amyloidosis

Accurate assessment of ventricular involvement in transthyretin cardiac amyloidosis (ATTR-CA) is essential for diagnosis and management. This study evaluated left and right ventricular (LV and RV) involvement in patients with ATTR-CA using single-photon emission computed tomography/computed tomography (SPECT/CT) witch Technetium-99m and 3,3-diphosphono-1,2-propanodicarboxylic acid ([^99mTc]Tc-DPD).

This prospective, single-centre study enrolled 100 adults from 2020 to 2024 (NCT05814380). Participants underwent clinical assessment, genetic testing, electrocardiography, echocardiography, and [^99mTc]Tc-DPD SPECT/CT. Volumetric and regional analyses of LV and RV amyloid burden were conducted. Patients were prospectively observed for 5 years to assess all-cause mortality.

Overall, RV uptake was observed in 91 % of patients with ATTR-CA. Radiotracer uptake was detected in the interventricular septum of all ATTR-CA patients, with apical involvement being less common (24 % hereditary ATTR vs. 31 % wild-type ATTR, p = 0.62). Notably, RV uptake was associated with RV thickness, LV global longitudinal strain, and N-terminal pro-brain natriuretic peptide levels (p = 0.00007, p = 0.00022, p = 0.00007; respectively). Multivariate analysis identified increased LV mass index and NYHA class as predictors of RV involvement (area under curve: 0.96). Volumetric LV and RV SPECT uptake measurements and apical sparing correlated with all-cause mortality (p < 0.001).

The presented findings confirm that SPECT/CT evaluation provides insights into both LV and RV involvement in patients with ATTR-CA and is associated with prognosis. Detailed assessment of RV involvement, through SPECT/CT, reveals significant structural and functional changes associated with disease severity. The presence of RV uptake is associated with advanced cardiac involvement, emphasising the importance of comprehensive biventricular evaluation in this patient population.