The CATCH-ATTR study: CArpal Tunnel ligament amyloid—the Clue for early identification of Hereditary or wildtype systemic ATTR amyloidosis?

Aims We sought to investigate the prevalence of Transthyretin amyloid (ATTR) deposits in the carpal ligament of patients undergoing surgery for carpal tunnel syndrome (CTS) and the frequency of concomitant ATTR-cardiomyopathy (CM) in a prospective study with long-term follow-up.Methods and results Our prospective exploratory study enrolled 551 patients treated for CTS. All resection specimens of carpal ligament underwent histopathological evaluation. Patients with confirmed amyloid deposits were referred to cardiac evaluation, including cardiac MRI (CMR) scans, as well as follow-up examinations. Amyloid deposits were found in 52 (9%) specimens (1 light chain amyloid, 51 ATTR). Among patients with positive biopsy ATTR-CM was diagnosed in 4 (8%) patients, 1 patient was diagnosed at initial evaluation, and 3 patients were diagnosed during the follow-up. All patients had ATTRwt at an early stage of disease. Extracellular volume (ECV) measured by CMR was significantly higher in amyloid-positive CTS patients compared to healthy controls (30 ± 2 vs. 24 ± 1%, p < .01).Conclusion Histopathological evaluation of resected carpal ligament should be considered in patients at least older than 70 years. Even though absolute numbers were low, cardiac screening of patients with evidence of amyloid deposits in in carpal tunnel tissues might facilitate early diagnosis of ATTR-CM in some patients.