Biomarkers and peak oxygen uptake in patients with chronic lung disease

Background: Peak oxygen uptake (peak VO(2)) is a predictor of outcome in patients with lung disease. In these patients, peak VO(2) is typically determined by ventilation and gas exchange. However, it is not well known whether cardiac strain contributes to peak VO(2) in patients with chronic lung disease.

Objective: To assess the relationship between several novel biomarkers reflecting different aspects of cardiac function and peak VO(2) in patients with chronic lung disease.

Methods: Plasma concentrations of midregional pro-A-type natriuret- ic peptide (MR-proANP), midregional proadrenomedullin (MR-proADM), C-terminal proendothelin-1 (CT-proET-1), and C-terminal provasopressin (copeptin) were measured in 85 patients with a variety of chronic pulmonary diseases [age 57 ± 14 years, forced expiratory volume in the 1st second (FEV(1)) 76 ± 23% of the predicted value] undergoing maximal cardiopulmonary exercise testing (peak VO(2) 18.6 ± 6.6 ml/kg/min).

Results: Raised MR-proANP (r = -0.54), MR- proADM (r = -0.54), and CT-proET-1 (r = -0.49; p < 0.001 for all) but not copeptin (r = -0.05; p = 0.68) concentrations were associated with lower peak VO(2), and these associations were independent of age, gender, medication, FEV(1) and oxygenation. The relationship between MR-proANP, MR-proADM, and CT-proET-1 and peak VO(2) was significant whether patients had an obstructive ventilatory disease or not.

Conclusions: In patients with chronic lung disease, several biomarkers known to reflect measures of cardiac function were associated with peak VO(2) independent of lung function, indicating that cardiac strain may contribute to exercise limitation in these patients due to concomitant cardiac disease or in the context of a pulmonary-cardiac interaction.