• biomarkers
• cardiac amyloidosis
• diagnosis
• NT-proBNP
• troponin

Background: Cardiac amyloidosis (CA) is associated with an elevation of natriuretic peptides and troponins, predicting outcome. Nevertheless, the diagnostic yield of these biomarkers has not been extensively investigated.

Aims: This study aimed to evaluate the diagnostic performance for CA of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity troponin T (hs-TnT).

Methods: Patients with suspected CA (n=1,149) underwent a diagnostic work-up in 3 Centres in Italy, France (n=343, derivation cohort), and United Kingdom (n=806, validation cohort). Biomarker values with either 100% sensitivity or ≥95% specificity were selected as rule-out/rule-in cut-offs, respectively.

Results: In the derivation cohort, 227 patients (66%) had CA, and presented with higher NT-proBNP and hs-TnT. NT-proBNP 180 ng/L and hs-TnT 14 ng/L were selected as rule-out cut-offs, and hs-TnT 86 ng/L as rule-in cut-off. NT-proBNP <180 ng/L or hs-TnT <14 ng/L were found in 7% of patients, ruled out without false negatives. In the validation cohort, 20% of patients (2% false negatives) had NT-proBNP <180 ng/L or hs-TnT <14 ng/L, and 10% showed both biomarkers below cut-offs (0.5% false negatives). These cut-offs refined CA prediction when added to echocardiographic scores in patients with a hematologic disease or an increased wall thickness. In the validation cohort, the 86 ng/L hs-TnT cut-off ruled in 20% of patients (2% false positives). NT-proBNP and hs-TnT cut-offs retained their rule-out and rule-in performance also in cohorts with CA prevalence of 20%, 10%, 5% and 1% derived from the original cohort through bootstrap analysis.

Conclusions: Cardiac biomarkers can refine the diagnostic algorithm in patients with suspected CA. NT-proBNP <180 ng/L and hs-TnT <14 ng/L reliably exclude the diagnosis, both in the overall population and subgroups referred for either a haematologic disease or cardiac (pseudo)hypertrophy.