Background: Six-minute walk distance (6MWD) independently predicts mortality and hospitalisation in Chronic Obstructive Pulmonary Disease (COPD) and is significantly reduced in COPD subjects with comorbidities of heart disease and hypertension. It also predicts cardiovascular events in stable coronary heart disease, and mortality in heart failure. We hypothesised that aortic stiffness is associated with 6MWD in COPD patients.

Methods: Interim analysis was performed on 354 stable subjects with COPD recruited to the ERICA (Evaluation of the role of inflammation in non-pulmonary manifestations of airways disease) study. Central haemodynamic measurements included aortic pulse wave velocity (aPWV) and augmentation index (AIx). Other measurements included carotid intima thickness, spirometry, 6MWD, fibrinogen and high-sensitivity C reactive protein (Hs-CRP).

Results: 210 out of 354 subjects (59%) were male, median (range) age 67 (43–84) years, 68% were former smokers. Mean aPWV was 10.2 (2.6) m/s. Linear regression analysis indicated a significant negative association between aPWV and 6MWD (p<0.001). This relationship was maintained after adjustment for airflow limitation (Forced Expiratory Lung Volume in 1 second [FEV₁]), age, sex, MAP and supine HR, p=0.011. A 1m/s increase in PWV was associated with a 9 m decrease in 6MWD (95% CI: 4–14 m, p=0.001).

Conclusions: Aortic stiffness is associated with 6MWD in COPD, suggesting a link between vascular ageing and functional limitation in this patient group, which merits further investigation. Reduced 6MWD in COPD subjects with cardiovascular comorbidity, suggests aortic stiffness may be involved in the increased prevalence of cardiovascular events seen in COPD.