Prognostics significance of small pulmonary vessels alteration measured by chest CT in connective tissue diseases with PAH

Abstract Background Pulmonary arterial hypertension (PAH) is characterized by structural alterations of the pulmonary vessels. Few studies have explored the clinical significance of quantitative assessment of pulmonary small vessels by chest CT. Our aim was to assess whether the prognosis of connective tissue diseases (CTD)-PAH patients could be asscessed through pulmonary small vessels measured by chest CT. Methods 42 CTD-PAH patients diagnosed based on right heart catheterization were retrospectively investigated. All patients underwent a chest CT within 1 month before and after RHC examination. Main pulmonary artery (MPA), the cross-sectional area of small pulmonary vessels < 5 mm 2 as a percentage of total lung area (%CSA< 5) were measured. The primary endpoint was a composite clinical worsening endpoint. Results After a median follow-up time of 30.5 (IQR, 8.5-45.25) months, endpoint events occurred in 16 (38.1%) patients after 19.5 (IQR 10.0-45.5) months. Cox univariate proportional hazard analysis showed that pulmonary vascular resistance, MPA diameter, and %CSA< 5 were associated with the endpoint. A combination of MPA diameter and %CSA< 5 was the independent risk factor for the prognosis (hazard ratio, 2.180 [95% CI, 1.405–3.383], P = 0.001). Kaplan-Meier analysis showed that CTD-PAH patients satisfying %CSA< 5 less than 0.382 and MPA greater than 36.75 mm had the highest risk of experiencing the endpoint. Conclusion Among the pulmonary vascular indicators measured by chest CT, in addition to MPA, %CSA< 5 may be a potential independent risk factor for poor long-term prognosis in Chinese CTD-PAH patients.