Increased Pulmonary Arterial Compliance after Balloon Pulmonary Angioplasty Predicts Exercise Tolerance Improvement in Inoperable CTEPH Patients with Lower Pulmonary Arterial Pressure

•Balloon pulmonary angioplasty (BPA) significantly improved pulmonary arterial compliance (CPA) in inoperable CTEPH patients.•The changes of CPA were significantly correlated with improvement of 6-min walk distance (6MWD) in inoperable CTEPH patients with mPAP < 30 mmHg.•CPA can be a useful index in symptomatic CTEPH patients who have lower mPAP. Balloon pulmonary angioplasty (BPA) improved pulmonary arterial compliance (CPA) and exercise tolerance in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH). To investigate whether CPA is a useful index to indicate exercise tolerance improvement by BPA in CTEPH patients. The correlation between changes in CPA and improvements in 6-minute walk distance (6MWD) by BPA was retrospectively analyzed in 70 patients (Analysis 1), and it was sequentially analyzed in 46 symptomatic patients who achieved mean pulmonary arterial pressure (mPAP)