Chronic thromboembolic vasculopathy with exercise induced PH but normal resting haemodynamics

Background Chronic thromboembolic pulmonary hypertension (CTEPH) is defined by chronic thromboembolic vascular obstruction and a mean pulmonary artery pressure (mPAP) of at least 25 mm Hg at rest. It is unclear how to manage symptomatic patients with disturbed lung perfusion due to chronic thromboembolic vascular abnormalities and mPAP below 25 mmHg at rest. Aims: To characterize subjects with mismatched chronic thromboembolic pulmonary perfusion abnormalities and mPAP Methods: We analyzed functional and haemodynamic parameters of 10 subjects with chronic thromboembolic pulmonary vasculopathy but normal mPAP at rest (CTEVP) and 31 CTEPH subjects. Results: CTEVP subjects presented with mPAP at rest of 20 +/- 2 mmHG. mPAP (44 +/-8 mmHg) but not PAWP (8 +/- 4 mmHg) rose under exercise condition. CTEVP subjects showed reduced functional capacity: WHO FC III: 9/10, II 1/10); 76 Watt; VO2 peak (14.8 ml/min/kg; 72 % pred.) Oxygen pulse (101 %) and breathing reserve (30 %) were normal. Dead space ventilation (21%) was elevated. The CTEVP cohort as well as the CTEPH subjects presented with functional signs of disturbed pulmonary perfusion (VE/VCO 2 : 46.0/49.4 (p=0.53); EQO 2 AT: 34.0/37.4 (p=0.27); EQCO 2 AT: 39.2/43.8 (p=0.24) , PETCO 2 AT: 28.0/27.0 mmHg (p=0.63); PaET CO 2 9.3/8.5 mmHg(p=0.58). Only P(A-a)O 2 36.1/52.1 mmHg (p=0.04) was significantly different. 4/10 CTEVP subjects underwent PEA. Following PEA 3 were asymptomatic, 1 improved from WHO FC III to II. Conclusion: Subjects with dyspnea and CTEVP but normal mPAP below 25mmHg at rest show similar functional limitations as CTEPH patients and can improve significantly following PEA.