Improving CT assessment for pulmonary hypertension in patients with severe aortic stenosis, correlation with right heart catheterization.

Purpose: To identify CT parameters useful for assessment of pulmonary hypertension (PH) in patients with severe aortic stenosis (AS).

Materials And Methods: Retrospective study of 165 patients who had undergone right heart catheterization (RHC), and CTA of the thorax for preoperative aortic valve replacement (TAVR) planning. These were divided into groups based on mean pulmonary artery (PA) pressure (mPAP) of 25 mm Hg on RHC (85 cases and 80 controls). Diameters of main pulmonary artery diameter (MPAD), left pulmonary artery (LPA), right pulmonary artery (RPA), and maximal long axis and short axis diameters of the right atrium (RA) and ventricle (RV) were measured on the axial plane. Univariate and multivariate statistical analysis was utilized to identify metrics predictive of PH.

Results: MPAD, LPA, and RPA were higher in subjects with mPAP >25 mm Hg (p < 0.0001 for all). Thresholds of 30.5 mm for MPAD (68.4% sensitivity, 82.7% specificity), and 27.5 mm for LPA and RPA (LPA: 51.9% sensitivity, 78.8% specificity; RPA: 62.0% sensitivity, 78.8% specificity) provided the best discrimination of elevated mPAP. Compared to literature values for MPAD (28.9 mm in men and 26.9 mm in women), these thresholds provide lower sensitivity but greatly increased specificity. Inclusion of RA enlargement to MPAD increased specificity to 98.5%, while inclusion of RV enlargement increased specificity to 100%.

Conclusion: Threshold to identify PH in patients with AS using PA enlargement is higher than previously reported range for normal. Inclusion of RA and RV enlargement improves the ability of CT to more accurately identify PH in patients with AS.