Patients’ Data and Grouping

Patients suspected of having CTEPH who underwent V/Q tomography at the China–Japan Friendship Hospital from March 2019 to January 2021 were retrospectively collected. CTEPH was diagnosed according to the 2015 ESC/ERS Guidelines for the Diagnosis and Treatment of Pulmonary Hypertension.¹ All patients received the standard anticoagulation therapy for at least three months, and CT pulmonary angiography, V/Q imaging, or pulmonary angiography confirmed the presence of chronic thrombosis. The examination of the right heart catheterization showed a mean pulmonary artery pressure (mPAP) in the resting state of ≥25 mmHg (1 mmHg = 0.133 kPa). Exclusion criteria: (1) patients with a history of lung surgery, vasculitis, pulmonary artery aneurysm, etc.; (2) an interval between V/Q imaging and pulmonary angiography >12 months; and (3) incomplete data on the examination of the right heart catheterization.

A total of 87 patients were analyzed, of which 83 were diagnosed with CTEPH, three with fibrosing mediastinitis, and one with Takayasu’s arteritis. Of the 83 patients diagnosed with CTEPH, 36 were males, and 47 were females, with an average age of 57.2 ± 12.7 y. The patients were classified according to the New York Heart Association Functional Classification, and 10 patients were classified as Class A, 37 as Class B, 30 as Class C, and 6 as Class D. The average six-minute walking distance (6MWD) was 386 ± 99 m. Patients were grouped according to the PAH risk stratification (World Symposium on Pulmonary Hypertension 2018),^6–8 and 37 patients were placed in the low-risk group, including 15 males and 22 females, with an average age of 55.4 ± 13.5 y, and 46 patients were placed in the medium-high-risk group, including 21 males and 25 females, with an average age of 58.6 ± 12.1 y (see Table 1). The study complied with the principles of the Declaration of Helsinki.

Risk Stratification in Pulmonary Arterial Hypertension

Abbreviations: 6MWD, six-minute walk distance; BNP, Brain Natriuretic Peptide; NT-proBNP, N terminal pro B type natriuretic peptide; RAP, right atrium pressure; CI, cardiac index; SvO2, mixed venous oxygen saturation.