Background: Several different B-type natriuretic peptide (BNP) assays are used clinically for diagnostic and prognostic evaluation of heart failure (HF). BNP binds weakly to neprilysin and is cleaved in multiple areas adjacent to the binding sites for the antibodies used in these immunoassays. We assessed the changes in BNP following neprilysin inhibition as measured by 3 immunoassays that recognize different epitopes.
Methods: Among 130 participants with HF with reduced ejection fraction, blood was collected prior to treatment with sacubitril/valsartan (sac/val) and then repeatedly measured through 52 weeks of treatment. BNP concentrations were measured with 3 widely used BNP assays (Siemens, Abbott, and Quidel).
Results: Study participants had a mean age of 65 ± 13 years and 76% were men. The median BNP concentration at baseline was 133 ng/L by the Siemens assay, 127 ng/L by the Abbott assay, and 141 ng/L by the Quidel assay. Following initiation of sac/val, there were significantly greater declines in BNP measured by Quidel and Abbott (P = 0.009 and P < 0.001), respectively (both with N-terminal capture antibodies), compared to Siemens (with C-terminal capture antibodies). The difference from baseline was not statistically significant until after week 12 (mean -10.1% for Quidel and -14.3% for Abbott) compared to non-significant differences before 12 weeks (mean -4.5% for Quidel and -6.0% for Abbott).
Conclusions: Following initiation of sac/val, BNP measurements may modestly differ depending on the assay method used, particularly after a few months of treatment. Whether these differences relate to neprilysin-mediated degradation of antibody binding sites deserves further study.
Study registration: PROVE-HF ClinicalTrials.gov Identifier: NCT02887183.
Keywords: BNP; angiotensin receptor neprilysin inhibitors; immunoassay; natriuretic peptide; neprilysin; sacubitril/valsartan.
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