Comparative measurement of N-terminal pro-brain natriuretic peptide and brain natriuretic peptide in ambulatory patients with heart failure

It is not clear whether brain natriuretic peptide (BNP) or Nterminal proBNP (NTproBNP) is superior as a diagnostic and prognostic indicator in cardiac diseases. Here, we compare the clinical correlations of both peptides in a population of 92 ambulatory patients with heart failure, using a wellestablished immunoradiometric assay (IRMA) for BNP and an automated electrochemiluminescence immunoassay for NTproBNP. The analytical correlation between the two peptides was satisfactory over a wide range of concentrations (1686 pM for BNP) with the equation: NTproBNP = 3.48 BNP 19 and a correlation coefficient r(2)=0.94. In addition, the concentration of both peptides increased in a similar fashion according to the severity of the disease New York Heart Association (NYHA) functional class, left ventricular ejection fraction, etiology) and age; for instance, the ratios between median levels measured in NYHA class III vs. class II patients were comparable for BNP (383 vs. 16 pM, ratio 24) and NTproBNP (1306 vs. 57 pM, ratio 23). We conclude that Nterminal proBNP, as assayed in the present study, correlates equally to BNP with clinical variables in patients with heart failure.