Abstract 4138014: Incidence and Association of Amyloidosis Found at Carpal Tunnel Release to Development of Cardiac Involvement

Background: Carpal tunnel syndrome (CTS) associated with transthyretin cardiac amyloidosis (ATTR-CA) may manifest 5 to 10 years prior to cardiac diagnosis. Transthyretin amyloidosis (ATTR) identification in the tenosynovium isolated during carpal tunnel release (CTR) may facilitate earlier ATTR-CA diagnosis and treatment. Hypothesis: Amyloid discovered at CTR will be associated with, and/or serve as a precursor for, cardiac involvement. Aim: We aimed to determine the frequency and type of amyloid found at CTR as well as the incidence of cardiac involvement and/or treatment indication. Methods: A retrospective analysis was conducted on a convenience sample of adults undergoing CTR from 01/05/2021 to 03/24/2023. Biopsy specimens with confirmed amyloid via Congo red staining were analyzed using mass spectrometry (MS) for subtyping. Patients with amyloid in tenosynovial tissue were offered cardiac evaluation with history and physical, electrocardiogram, B-type natriuretic peptide, troponin-I HS, echocardiogram, and TcPYP nuclear scintigraphy. Patients with light-chain amyloidosis (AL) were referred to oncology, while patients with ATTR were offered genetic testing. Results: A total of 578 patients underwent CTR with tenosynovial sample excision. Amyloid involvement by Congo red staining was found in 43 patients (7.4%), with a definitive subtype confirmed by MS in 30 patients (5.2%). Samples were insufficient to define subtypes in 13 patients. Sole ATTR was found in 27 patients (4.7%), both AL and ATTR were found in 1 patient, and sole AL was found in 2 patients. Of the 28 ATTR patients (the patient with both ATTR and AL included), 24 pursued genetic testing, revealing all had wild-type ATTR. Of these 28 patients, 21 underwent cardiac evaluation, for which 2 had cardiac involvement on TcPYP and started tafamidis therapy. The patients with concomitant ATTR and AL or sole AL did not have evidence of cardiac involvement, however, chemotherapy was initiated as indicated. Unfortunately, 1 patient with AL on CTR did not pursue an evaluation. Conclusion: Incidental amyloid tissue found at CTR is common and associated with occult involvement warranting therapy in a minority of cases. Future cardiac involvement is unknown, and this cohort will be followed to determine future incidence. A startling number of patients were found to have occult systemic AL discovered at CTR. These incidental diagnoses may trigger lifesaving interventions, which may otherwise go undiagnosed.