Vascular involvement in chronic thromboembolic pulmonary hypertension is associated with spirometry obstructive impairment

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) is a type of pulmonary hypertension caused by persistent thromboembolism of the pulmonary arteries. In clinical practice, CTEPH patients often show obstructive ventilatory impairment, even in the absence of a smoking history. Recent reports imply a tendency for CTEPH patients to have a lower FEV(1.0); however, the mechanism underlying obstructive impairment remains unknown. METHODS: We retrospectively analyzed CTEPH patients who underwent a pulmonary function test and respiratory impedance test to evaluate their exertional dyspnea during admission for right heart catheterization from January 2000 to December 2019. We excluded patients with a smoking history to rule out the effect of smoking on obstructive impairment. RESULTS: A total of 135 CTEPH patients were analyzed. The median FEV(1.0)/FVC was 76.0%, %FEV (1.0) had a negative correlation with the mean pulmonary artery pressure and pulmonary vascular resistance and the CT Angiogram (CTA) obstruction score. A multivariate regression analysis revealed that the CTA obstruction score was an independent factor of a lower %FEV(1.0). In the 54 patients who underwent pulmonary endarterectomy, %FEV(1.0) was improved in some cases and was not in some. Mean PAP largely decreased after PEA in the better %FEV(1.0) improved cases, suggesting that vascular involvement in CTEPH could be associated with spirometry obstructive impairment. CONCLUSION: %FEV(1.0) had a significant correlation with the CTA obstruction score. Obstructive impairment might have an etiological relationship with vascular involvement. Further investigations could shed new light on the etiology of CTEPH. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12890-021-01779-x.