Pulmonary arterial compliance and exercise capacity after balloon pulmonary angioplasty in chronic thromboembolic pulmonary hypertension

Objective To determine whether changes in pulmonary vascular resistance (PVR) and changes in pulmonary artery compliance (Cpa) are associated with changes in exercise capacity assessed either by changes in peak oxygen consumption (V′O2) or by changes in 6-min walk distance (6MWD) in patients with chronic thromboembolic pulmonary hypertension (CTEPH) undergoing balloon pulmonary angioplasty (BPA). Methods Invasive haemodynamic parameters, peakV′O2and 6MWD were measured within 24 h, before and after BPA (interval 3.1±2.4 months) in 34 CTEPH patients without significant cardiac and/or pulmonary comorbidities, of whom 24 received at least one pulmonary hypertension-specific treatment.Cpawas calculated according to the pulse pressure method:Cpa=((SV/PP)/1.76+0.1), where SV is the stroke volume and PP is the pulse pressure. The resistance–compliance (RC)-time of the pulmonary circulation was calculated as the PVR andCpaproduct. Results After BPA, PVR decreased (562±234versus290±106 dyn·s·cm−5; p<0.001);Cpaincreased (0.90±0.36versus1.63±0.65 mL·mmHg−1; p<0.001); but RC-time did not change (0.325±0.069versus0.321±0.083 s; p=0.75). There were improvements in peakV′O2(1.11±0.35versus1.30±0.33 L·min−1; p<0.001) and in 6MWD (393±119versus432±100 m; p<0.001). After adjustment for age, height, weight and gender, changes in exercise capacity, assessed either by peakV′O2or 6MWD, were significantly associated with changes in PVR, but not with changes inCpa. Conclusions Contrary to what has been reported in CTEPH patients undergoing pulmonary endarterectomy, in CTEPH patients undergoing BPA, changes in exercise capacity were not associated with changes inCpa.