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 (C pa) 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, peak V'O2 and 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. C pa was calculated according to the pulse pressure method: C pa=((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 and C pa product. Results: After BPA, PVR decreased (562±234 versus 290±106 dyn·s·cm-5; p<0.001); C pa increased (0.90±0.36 versus 1.63±0.65 mL·mmHg-1; p<0.001); but RC-time did not change (0.325±0.069 versus 0.321±0.083 s; p=0.75). There were improvements in peak V'O2 (1.11±0.35 versus 1.30±0.33 L·min-1; p<0.001) and in 6MWD (393±119 versus 432±100 m; p<0.001). After adjustment for age, height, weight and gender, changes in exercise capacity, assessed either by peak V'O2 or 6MWD, were significantly associated with changes in PVR, but not with changes in C pa. 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 in C pa.