Diastolic Dysfunction Is a Contributing Factor to Exercise Intolerance in COPD

Right ventricular (RV) systolic failure is rare in patients with COPD, but they often develop RV diastolic dysfunction. Left ventricular (LV) diastolic dysfunction is also common in this population. Nevertheless, data are scarce regarding the effect of diastolic dysfunction on the functional capacity in patients with COPD. We investigated the correlation between echocardiographic parameters of RV and LV diastolic function and the exercise capacity in COPD, by using conventional echocardiographic methods and tissue Doppler imaging. 65 patients with COPD (61 +/- 9 years) in stages GOLD II-IV were investigated. Functional capacity was measured with 6-minute walk test (6MWT). Right (RA) and left atrial (LA) area index were measured; collapsibility index inferior vena cava was calculated. Parameters of the mitral and tricuspid inflow(E, A) as well as annular systolic (S), early-(e') and late-(a') diastolic myocardial longitudinal velocities were measured. E/A, E/e' and e'/a' ratios were calculated. 6MWT distance was 330 +/- 76 m. LV diastolic dysfunction was found in 48 (74%) patients. LV and RV filling pressures were elevated in 28 (43%) and in 29 (45%) patients, respectively. In the left heart, LA area index showed significant correlation with the functional capacity (r=-0.319; p=0.011). In stepwise multiple linear regression analysis tricuspid e'/a' (r=0.611; p=0.000), collapsibility index (r=0.505; p=0.000), RA area index (r=-0.445; p=0.000) and body surface area (r=0.314; p=0.011) were independent predictors of 6MWT distance. Right ventricular diastolic function and filling pressure have strong influence on the functional capacity in patients with COPD.