CT-Measured Lung Air-Trapping is Associated with Higher Carotid Artery Stiffness in Individuals with Chronic Obstructive Pulmonary Disease.

Early stages of chronic obstructive pulmonary disease (COPD) are characterized by the loss and narrowing of terminal bronchioles in the lung resulting in 'air-trapping,' often occurring before overt emphysema manifests. Individuals with an airway-predominant phenotype of COPD display extensive lung air-trapping and are at greater cardiovascular disease (CVD) risk than COPD patients with an emphysema-predominant phenotype. We hypothesized that the degree of computed tomography (CT)-quantified lung air-trapping would be associated with greater aortic and carotid artery stiffness and lower endothelial function, known biomarkers of CVD risk. Lung air-trapping was associated with greater aortic stiffness (carotid femoral pulse wave velocity, CFPWV) (r=0.60, p=0.007) and carotid β-stiffness (r=0.75, p=0.0001) among adults with (n=10) and without (n=9) a clinical diagnosis of COPD and remained significant after adjusting for blood pressure (BP) and smoking history (pack-years) (carotid β-stiffness r=0.68, p<0.01; CFPWV r=0.53, p=0.03). The association between lung air-trapping and carotid β-stiffness remained significant after additionally adjusting for age and FEV1 (r=0.64, p=0.01). In the COPD group only (n=10), lung air-trapping remained associated with carotid β-stiffness (r=0.82, p=0.05) after adjustment for age, pack-years and FEV1 . In contrast, no association was observed between CFPWV and lung air-trapping after adjustment for BP, pack-years, age and FEV1 (r=0.12, p=0.83). Lung air-trapping was not associated with endothelial function (brachial artery flow mediated dilation) in the entire cohort (p=0.80) or in patients with COPD only (p=0.71). These data suggest that carotid artery stiffness may be a mechanism explaining the link between airway- predominant phenotypes of COPD and high CVD risk.