Diagnostic accuracy of plasma brain natriuretic peptide and aminoterminal‐proBNP in mild heart failure depends on assay and introduction of therapy

Abstract

Objective. A reliable biochemical marker of left ventricular dysfunction (LVD) could improve diagnostic accuracy. The aim of this study was to compare the correlation of measurements of brain natriuretic peptide (BNP) and N‐terminal proBNP (NT‐proBNP) with different assays. The diagnostic accuracy of the tests in mild heart failure (HF) was estimated before and after the start of therapy. Material and methods. Doppler echocardiography and measurements of plasma BNP and NT‐proBNP were performed in 150 patients. Results. Systolic dysfunction (LV ejection fraction⩽0.45) was present in 22 patients, and 58 had only abnormalities in LV filling. P‐NT‐proBNP based on two different assays demonstrated a moderate correlation (r = 0.57, p<0.0001) and a concentration‐dependent systematic difference. Excellent correlation (r = 0.95, p<0.0001) was found between BNP and NT‐proBNP based on two‐site antibody assays, but was moderate between BNP and a one‐site antibody NT‐proBNP assay (r = 0.58, p<0.0001). Areas under the receiver operating characteristic (ROC) curves (AUCs) were 0.93 (95 % CI, 0.90–0.98) for BNP, 0.95 (0.91–0.99) for NT‐proBNP (two‐site antibody assay) and 0.77 (0.70–0.85) for the one‐site antibody NT‐proBNP assay (p = 0.0001). At re‐evaluation of LVD at 6 and 12 months, AUCs of BNP were 0.81 (0.74–0.99) and 0.83 (0.76–0.89), respectively, and AUCs of NT‐proBNP (two‐site) were 0.84 (0.77–0.91) and 0.87 (0.81–0.93), respectively. Using the baseline threshold reduced the sensitivity and specificity of BNP and NT‐proBNP measurements. Conclusions. BNP and NT‐proBNP measurements demonstrated assay‐dependent correlations. Measurement of p‐BNP or p‐NT‐proBNP by a two‐site antibody assay demonstrated potential as an indicator of mild, incident HF, but the applicability of the index tests was limited over time and was likely influenced by therapeutic interventions.

• Biochemical marker
• correlation
• echocardiography
• heart failure with preserved systolic function
• therapeutic intervention

Acknowledgements

This work was funded by a grant from The Danish Heart Foundation. We thank Professor Werner Vach for statistical support.