Pro-brain natriuretic peptide as marker of cardiovascular or pulmonary causes of dyspnea in patients with terminal parenchymal lung disease

BACKGROUND: Increased plasma concentrations of pro-atrial natriuretic peptide (proANP) and pro-brain natriuretic peptide (proBNP) are features of left ventricular impairment. However, concentrations of proANP and proBNP in patients with isolated terminal parenchymal lung disease are not known. Therefore, we measured the plasma concentrations of natriuretic precursor peptides in patients with terminal parenchymal lung disease who had normal left ventricular function and who were referred for evaluation for lung transplantation.

METHODS: We measured plasma N-terminal proANP and proBNP in patients undergoing right heart catheterization (n = 50) and related results to hemodynamic variables obtained during catheterization.

RESULTS: Plasma proBNP concentrations were unaffected in patients with terminal parenchymal lung disease and normal left ventricular function (median, 2.5 pmol/liter; range, 0-22; upper reference limit, 15 pmol/liter). In contrast, patients with primary pulmonary hypertension displayed more than a 40-fold increase in plasma proBNP concentrations (median, 107 pmol/liter vs 2.5 pmol/liter, p < 0.0001). Plasma N-terminal proANP increased moderately (median, 664 pmol/liter; range, 36-1620; upper reference limit, 600 pmol/liter) but correlated to plasma proBNP concentrations (r = 0.47, p < 0.0001). Finally, regional vascular proBNP concentrations revealed the heart as the secretory site.

CONCLUSIONS: Our findings strongly support the contention that natriuretic peptide measurements are efficient markers for cardiovascular causes of dyspnea. Moreover, our results eliminate natriuretic peptides as markers of moderate pulmonary hypertension in patients with terminal parenchymal lung disease.