Functional Characterization of Patients with Chronic Thromboembolic Disease

Background: Patients with chronic thromboembolic pulmonary disease (CTED) have persistent pulmonary vascular obstruction and exercise intolerance without pulmonary hypertension at rest and may benefit from pulmonary endarterectomy. However, up to now, CTED has been poorly characterized. Objectives: This study aimed to analyze the exercise capacity and limiting factors in CTED. Methods: We compared right heart catheterization and cardiopulmonary exercise test results of patients with CTED [mean pulmonary artery pressure (mPAP) at rest Results: Subjects with CTED show a reduced oxygen uptake [median 76/interquartile range (IQR) 22% pred.] and work rate (median 76/IQR 21 W). The work rate was significantly lower compared to control subjects (p = 0.04) but not significantly different from CTEPH patients (p = 0.66). Oxygen pulse and breathing reserve were normal. CTED subjects showed decreased end-tidal CO2 at anaerobic threshold (28.4/4.3 mm Hg), an elevated VE/VCO2 slope (42.5/23.5), breathing equivalents (EQO2 32.0/8.7, EQCO2 39.5/8.8), alveolar-capillary oxygen gradient (34.7/15.5 mm Hg) and capillary end-tidal carbon dioxide gradient (8.8/5.7 mm Hg) compared to control subjects (p Conclusions: Despite an mPAP of