Background: Computed tomography pulmonary angiography (CTPA) is an integral part of the work-up in patients with suspected pulmonary hypertension (PH). However, there is no established CTPA-derived prognostic marker.

Aim: To assess whether quantitative readouts of lung vessel morphology correlate with established prognostic indicators.

Methods: Patients with pre-capillary PH who underwent right heart catheterization and CTPA between May 2016 and May 2019 were enrolled in this retrospective study. Lung vessel morphology was determined with a fully-automatic in-house developed algorithm for segmentation of arteries and veins. Primary endpoint was the calculation of receiver operating characteristics for identifying low and high mortality risk according to the 3-strata risk assessment model presented in the current guidelines.

Results: We analysed 73 patients, median age 65 years (IQR: 54-76), 48% women, median mean pulmonary arterial pressure 37 mmHg (IQR: 30-46), and found correlations with important prognostic factors in PAH. N-terminal pro-brain natriuretic peptide, cardiac index, mixed venous oxygen saturation and six-minute walking distance were correlated with the ratio of the number of arteries over veins with vessel diameters of 6-10 mm (Spearman correlation coefficients ?=0.64, -0.60, -0.47 and -0.45, respectively; all p?0.005). This ratio predicted low- and high-risk scores with an area under the curve of 0.73 (95% CI: 0.56-0.90) and 0.86 (95% CI: 0.74-0.97), respectively.

Conclusion: The ratio of the number of arteries over veins with diameters between 6-10 mm is significantly correlated with prognostic markers in pre-capillary PH and predicts low and high mortality risk.