NPPB and AL amyloidosis: In 2004, Dispenzieri et al. collected and analyzed the clinical data of 242 AL amyloidosis patients from the Mayo Clinic and found that an N-terminal pro B-type natriuretic peptide (NT-proBNP) > 332 ng/L, cardiac troponin T (CTNT) > 0.035 μg/L, or cardiac troponin I (CTNI) > 0.1 μg/L level was a poor prognostic factor 1.