Correlation of a decline in aerobic capacity with development of emphysema in patients with COPD

Abstract

Background: In COPD patients, CT assessment of emphysema and airway disease is associated with lung function and 6-minute walk distance. However, it remains to be determined whether low attenuation area (LAA) on CT is associated with aerobic capacity (VO2) assessed using cardiopulmonary exercise testing (CPET). Methods: In this prospective observational study, we repeatedly conducted high-resolution CT and CPET using a treadmill in 81 COPD patients over a median interval of 3.5 years. Two investigators independently scored LAA on images obtained at the aortic arch, tracheal bifurcation, and supradiaphragmatic levels. Grades for the images of each lung were added to yield the total LAA score. Results: Total LAA score was negatively correlated with peak VO2 (p<0.001, r=-0.485). There was a significant correlation between total LAA score and peak CO2 output (VCO2) (p<0.001, r=-0.433). The mean annual change in total LAA score was significantly correlated with those in peak VO2 (p<0.001, r=-0.546) and peak VCO2 (p Conclusion: The extent of emphysema measured by CT was associated with the results of CPET. The time-dependent changes in CPET data were also correlated with that in total LAA score. CT assessment could be a non-invasive tool to predict aerobic capacity in patients with COPD.