Accuracy of CT-derived measures in identifying Pulmonary Hypertension (PH) in patients awaiting lung transplant

Background: Screening for PH is mandatory in patients awaiting lung transplant (LTx) as it may impact treatment strategy. Transthoracic echocardiography may be challenging in some patients and routine right heart catheterization (RHC) should be performed. Pulmonary Artery diameter (dPA) and the ratio of dPA to the diameter of the ascending aorta (dAP/dAo) have been suggested to predict the presence of PH in COPD and interstitial lung disease (ILD), but studies have elicited conflicting results. Aims: To determine the accuracy of CT-derived measures in identifying PH in patients awaiting LTx for COPD or ILD. Methods: This was a retrospective single center study. Patients were eligible if they had COPD or ILD, had been listed for LTx between 2012 and 2016, and had undergone RHC within 6 months from a CT scan. PH was defined as mean pulmonary artery pressure (mPAP) ≥25 mmHg. Both dPA and dAo were measured by 2 radiologists at the level of the bifurcation of the pulmonary artery and mean values were used. Results: 13 COPD and 20 ILD patients were included. Of those, 15 had PH. There was no correlation between mPAP and either dPA or dPA/dAo ratio (pu003e0.05). Also, median (IQR) dPA and dPA/dAo ratio were similar for patients with and without PH (dPA: 26.6mm (23.9-33.6) vs. 27.5mm (23.9–29.4); dPA/dAo: 0.85 (0.76–1.03) vs. 0.90 (0.79–0.96). Traditionally used cut off values of dPA (u003e30 mm) and dPA/dAo (u003e1.0) showed high specificity for PH (87% and 93%, respectively), but very low sensitivity (29% and 24%, respectively) and negative predictive values were 48% and 52%. Conclusion: CT-derived measures of dPA and dPA/dAo should not be used to screen for PH in this population.