Long-Term Impact of Eplontersen on Technetium-99m-Pyrophosphate Single-Photon Emission Computed Tomography/Computed Tomography in Ala97Ser Hereditary Transthyretin Amyloid Cardiomyopathy.

BACKGROUND: Hereditary transthyretin amyloid cardiomyopathy (hATTR-CM) is a progressive disease. Emerging evidence supports bone scintigraphy as a noninvasive tool for monitoring treatment response. We aimed to evaluate the long-term impact of eplontersen therapy on technetium-99m pyrophosphate (99mTc-PYP) single-photon emission computed tomography/computed tomography (SPECT/CT) uptake in patients with hATTR-CM. METHODS: We retrospectively analyzed data from a prospective cohort enrolled in the NEURO-TTRansform trial, including hATTR-CM patients treated with eplontersen. Patients who underwent baseline and at least two post-treatment 99mTc-PYP SPECT/CT imaging were included. Changes in biomarkers, echocardiographic and 99mTc-PYP SPECT/CT parameters were assessed. RESULTS: Five patients met the inclusion criteria. The mean follow-up durations were 22.4 months (first follow-up) and 37.5 months (second follow-up). A significant reduction in the volumetric heart-to-lung ratio was observed from baseline to first follow-up (3.75 ± 0.53 to 2.94 ± 0.38, p = 0.010) and to second follow-up (3.75 ± 0.53 to 2.86 ± 0.39, p = 0.009). A further reduction between the first and second follow-up was also noted (2.94 ± 0.38 to 2.86 ± 0.39, p = 0.025). CONCLUSIONS: Serial 99mTc-PYP SPECT/CT imaging demonstrated a significant reduction in myocardial tracer uptake over a mean follow-up of 37.5 months in patients with hATTR-CM undergoing eplontersen therapy.