Pulmonary Artery Size on CT Associates with Mean Pulmonary Artery Pressure and Mortality

Rationale: Pulmonary artery (PA) dilation on CT has been associated with moderate-severe pulmonary hypertension (PH) using outdated diagnostic criteria. The association between PA size and mean PA pressure (mPAP) in mild PH and the prognostic implications of PA dilation remain unclear. Objectives: To investigate associations between PA size, mPAP, and survival in subjects without significant lung disease aside from PH. Methods: PA size on CT was measured for individuals with group 1 or 2 PH and matched controls in the Pulmonary Vascular Disease Phenomics cohort. Outcomes included mPAP on right heart catheterization (RHC) and time to heart and/or lung transplantation or death. Measurements and Main Results: 691 subjects were included, with 595 undergoing RHC. PA diameter and PA:aorta ratio demonstrated significant association with mPAP (ρ = 0.557 and 0.564, respectively). Size increased incrementally from no PH to mild PH to moderate-severe PH for PA diameter (27.64 95% CI 17.64-37.64 to 30.65 18.99-42.31 to 36.00 22.46-49.54 mm) and PA:aorta (0.89 0.53-1.24 to 0.99 0.63-1.35 to 1.19 0.60-1.78). PA diameter and PA:aorta demonstrated good discrimination of mPAP > 20 mmHg (AUC 0.834 and 0.816, respectively). Transplant-free survival decreased across the continuum of PA diameter and PA:aorta (p < 0.001). Adjusted hazard ratio of third versus first quartile values was 2.36 1.58-3.54 for PA diameter and 2.24 1.52-3.30 for PA:aorta. Conclusions: In subjects without significant lung disease outside of PH, PA size on CT was associated with increased mPAP and decreased transplant-free survival across the spectrum of PH severity and demonstrated modest diagnostic discriminatory ability using updated hemodynamic criteria. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).