Clinical characteristics and prediction of pulmonary hypertension in severe emphysema

Abstract

We explored the prevalence, clinical and physiologic correlates of pulmonary hypertension (PH), and screening strategies in patients with severe emphysema evaluated for the National Emphysema Treatment Trial (NETT). Patients undergoing Doppler echocardiography (DE) and right heart catheterization were included. Patients with mean pulmonary arterial pressure ≥ 25 mmHg (PH Group) were compared to the remainder (non-PH Group). Of 797 patients, 302 (38%) had PH and 18 (2.2%) had severe PH. Compared to the non-PH Group, patients with PH had lower % predicted FEV1 (p < 0.001), % predicted diffusion capacity for carbon monoxide (p = 0.006), and resting room air PaO2 (p < 0.001). By multivariate analysis, elevated right ventricular systolic pressure, reduced resting room air PaO2, reduced post-bronchodilator % predicted FEV1, and enlarged pulmonary arteries on computed tomographic scan were the best predictors of PH. A strategy using % predicted FEV1, % predicted DLCO, PaO2, and RVSP was predictive of the presence of pre-capillary PH and was highly predictive of its absence. Mildly elevated pulmonary artery pressures are found in a significant proportion of patients with severe emphysema. However, severe PH is uncommon in the absence of co-morbidities. Simple non-invasive tests may be helpful in screening patients for pre-capillary PH in severe emphysema but none is reliably predictive of its presence.