B-type natriuretic peptide and amino-terminal pro-B-type natriuretic peptide in pediatric patients with pulmonary arterial hypertension

Abstract

Objectives: B-type natriuretic peptide (BNP) and the amino-terminal fragment (NTproBNP) correlate with clinical variables, but have not been simultaneously studied in a large number of pediatric patients with pulmonary arterial hypertension (PAH). The purpose of our investigation was to compare BNP and NTproBNP with clinical indicators of disease in a pediatric PAH population for which biomarkers are much needed.

Design: We retrospectively compared BNP and NTproBNP levels with exercise capacity, echocardiographic data, and hemodynamics in PAH patients under 21 years old. Two hundred sixty-three blood samples from 88 pediatric PAH patients were obtained, with BNP and NTproBNP drawn at the same time.

Results: There was a correlation between BNP and NTproBNP with mean pulmonary arterial pressure/mean systemic arterial pressure ratio (r= 0.40, P < .01; r= 0.45, P < .01; respectively), mean right atrial pressure (r= 0.48, P < .01; r= 0.48, P < .01), and tricuspid regurgitant velocity (r= 0.36, P < .01; r= 0.41, P < .01). BNP and NTproBNP are associated with 6-minute walk distance, mean pulmonary arterial pressure, mean pulmonary arterial pressure/mean systemic arterial pressure ratio, mean right atrial pressure, pulmonary vascular resistance index, and tricuspid regurgitant velocity when investigated longitudinally. On the average, a 1-unit increase in log BNP or NTproBNP was associated with 4.5 units × m(2) or 3.4 units × m(2) increase in pulmonary vascular resistance index, respectively. There was a strong correlation between log BNP and log NTproBNP measurements (r= 0.87, P < .01).

Conclusion: In pediatric PAH, BNP and NTProBNP are strongly correlated and predict changes in clinical variables and hemodynamics. In a cross-sectional analysis, NTproBNP correlated with echocardiographic and exercise data better than BNP; NTproBNP showed less within patient variability over time; therefore, NTproBNP can add additional information toward predicting these clinical measurements.

Conflict of interest statement

Disclosures: The authors have no conflicts of interest to disclose.

© 2012 Wiley Periodicals, Inc.

Figures

Figure 1. Concentrations for BNP (Blue) and NTproBNP (green) versus age

The general trend for males (solid line) and females (dashed line) are displayed separately using a scatterplot smoother. (236 samples in 88 patients) * BNP; B-type natriuretic peptide, NTproBNP; amino-terminal fragment B-type natriuretic peptide

Figure 2. Scatterplot displaying the cross-sectional relationship between BNP and NTproBNP

The relationship between NP marker values is displayed; the diagonal line corresponds to the line of equivalence. The majority of the points lie below this line showing that the measured values of BNP were lower than the NTproBNP measurements obtained from the same sample. (88 samples in 88 patients)

Figure 3. The t-statistics corresponding to BNP and NTproBNP testing the association with each of the clinical variables estimated from serially collected measurements

NTproBNP had larger t-values for 6MWD, TR velocity, peak VO2 and VE/VCO2 compared to BNP, suggesting a better association. * 6MWD; 6 minute walking distance, mPAP; mean pulmonary arterial pressure, mSAP; mean systemic arterial pressure, mRAP; mean right atrial pressure, PVRI; pulmonary vascular resistance index, CI; cardiac index, TR; tricuspid regurgitation, LVFS; left ventricular fractional shortening, Peak VO2; peak oxygen consumption, VE/VCO2; ratio of minute ventilation to carbon dioxide output

Figure 4. Correlations between serial TR velocity and natriuretic peptides measurements

BNP and NTproBNP were significantly associated with TR velocity (slope=34 (m/s)/ (log pg/ml), p<0.01, slope=40.0 (m/s)/(log pg/ml), p<0.01, respectively). However, there was no statistical difference between NTproBNP and BNP slopes. (214 samples in 69 patients)