Value of troponin and NT-proBNP to screen for cardiac amyloidosis after carpal tunnel syndrome surgery

Background: Early diagnosis of cardiac amyloidosis (CA) is crucial due to the promising effect of disease- modifying treatment. This calls for screening strategies to identify CA patients with so-called "red flags", such as carpal tunnel syndrome (CTS). Objectives: This study aims to assess Troponin-T (TnT) and N-terminal pro-B-type natriuretic peptide (NTProBNP) as predictors for CA in patients with a history of surgery for bilateral carpal tunnel syndrome, a population suitable for systematic screening. Methods: Subjects with a history of surgery for bilateral CTS 5-15 years prior, identified using national registries were investigated for CA as per international recommendations. Sensitivity, specificity, positive and negative predictive values were assessed, and receiver operating curves were generated using logistic regression. Results: Among the 250 participants, 12 were diagnosed with CA, all with wild-type transthyretin amyloidosis. Elevated TnT levels (>= 13 ng/L) were found in all CA patients and 25.6% (+/- 2.8) of non-CA patients. The negative predictive value (NPV) of TnT <13 ng/L was 100%. For NT-ProBNP the NPV was 99.1% when age dependent cutoff levels were used. A combination of both biomarkers yielded an NPV of 99.1% and sensitivity of 99.7%. Early disease (Mayo or NAC stage 1) was found in 83% of identified patients with CA. Conclusion: This study demonstrates the utility of TnT and NT-ProBNP as negative predictors to exclude CA in a screening population with a history of surgery for CTS.