Comparative Study on Cardiac Findings in Patients with Transthyretin Amyloidosis Before and After Treatment with a Transthyretin Silencer.

Transthyretin amyloidosis (ATTR) is a rare disease caused by misfolded proteins, amyloids, that are deposited in various organs and tissues, typically the heart and/or nerves, causing the development of cardiomyopathy (CM) and polyneuropathy (PN). Although this may be an incurable disease, there are various treatments that are currently available for patients with ATTR, including transthyretin (TTR) silencers such as inotersen and patisiran. The silencers help slow down the progression of disease and improve the quality of life of patients with ATTR by alleviating the cardiac and neurological symptoms that patients present. The purpose of this study was to compare the cardiac findings observed in the ⁹⁹Tc-PYP scintigraphy (PYP scan) parameters of patients with a mixed phenotype before and after treatment with inotersen or patisiran. This study included ten patients from the amyloidosis clinic at the University Health Network. All of the patients (average age: 63.80 ± 11.70; 60.0% males, 40.0% females) received inotersen or patisiran as their treatment. These patients underwent a PYP scan before and after treatment to observe any improvements in terms of their CM post-treatment. Nine (90.0%) patients showed an improvement with their CM, as they showed a decrease in their heart-to-contralateral lung (H/CL) ratio and/or pyrophosphate (PYP) grade based on their results from the PYP scan post-treatment with a TTR silencer. Only one patient (10.0%) had worsening results, as their H/CL ratio and PYP grade increased post-treatment in comparison to the PYP scan results pre-treatment. Patients with ATTR who have a mixed phenotype should undergo a PYP scan before and after treatment with a TTR silencer. By undergoing these scans, the effectiveness of this treatment could be determined by observing any improvements in the signs of CM. A decrease in the H/CL ratio and/or the PYP grade would indicate that the TTR silencer has been effective in alleviating the signs and symptoms of CM, and that the patients should continue with their treatment plan.