Ratio of pro-B-type natriuretic peptide (BNP) to total BNP is decreased in mild, but not severe, acute decompensated heart failure patients: A novel compensatory mechanism for acute heart failure.

ABSTRACT

BACKGROUND: A recent study showed that both glycosylation of pro-B-type natriuretic peptide (BNP) and the proBNP/total BNP ratio are decreased in acute decompensated heart failure (ADHF). However, the following points regarding the proBNP/total BNP ratio have not been determined in patients with ADHF 1) the relationship with the severity of ADHF, 2) the changes in the ratio during treatment, and 3) the relationship with cyclic guanosine monophosphate (cGMP)-generating activity. METHODS: Plasma proBNP and total BNP (proBNP+mature BNP) were measured in patients with ADHF (n=154). Measurement was performed on admission, 3 and 7days after admission, and before discharge using recently developed sandwich chemiluminescence enzyme immunoassays. The percent proBNP was calculated as (proBNP/total BNP)×100. RESULTS: On admission, %proBNP was higher in patients with severe ADHF than in patients with mild ADHF (median 61.7% vs. 56.2%, respectively; p<0.01), while the plasma cGMP/total BNP ratio, an index of the biological activity of BNP, was lower (p<0.001). In patients with severe ADHF, the higher %proBNP and lower cGMP/total BNP ratio were unchanged during hospitalization, whereas %proBNP increased gradually in patients with mild ADHF and the cGMP/total BNP ratio also increased at 3days after admission. CONCLUSION: These findings suggest that in patients with mild ADHF, compensation for heart failure occurs via increased proBNP processing, leading to increase of mature BNP and activation of the BNP/cGMP cascade. In contrast, this compensatory mechanism may be impaired in patients with severe ADHF and a vicious cycle can potentially occur.