PURPOSE: Aim of this study was to determine whether the ratio of diameter of main pulmonary artery and of ascending aorta (rPA/Ao), as assessed on computed tomography (CT), is predictive of pulmonary artery hypertension (PAH) in patients with collagen vascular disease.
METHODS: 19 patients with documented collagen vascular disease (scleroderma, mixed connective tissue disorder) and proven PAH (mean pulmonary artery pressure >25 mm Hg) who had a CT angiogram and right heart catheterization were studied. Controls (n=7) were defined as patients who were evaluated for unexplained dyspnea on exertion but were not confirmed to have PAH either by echocardiogram or right heart catheterization. The measure of rPA/Ao was performed by a pulmonary fellow and attending radiologist on a single defined CT section. Statistical analysis was done using the software Mathcad.
RESULTS: The rPA/Ao was >1 in 7 of 19 patients with PAH. In those with rPA/Ao <1 (n=12), mean PA diameter (dPA) was 2.9 +/− 0.3 cm vs. 2.3 +/− 0.3 cm for control [p < 0.0012]. Using receiver operator curve characteristics, a cut off value of 2.5 was determined as the best discriminator. With this cutoff, sensitivity of dPA to predict a presence of PAH was 0.889, specificity was 0.857, and negative predictive value was 0.857. Correlation data was obtained for 17 patients with confirmed PAH for which hemodynamic data was available. dPA correlated with mean right ventricular pressure [r= 0.502] and mean pulmonary artery pressure [r= 0.587].
CONCLUSION: In a cohort of patients with collagen vascular disorders and proven PAH, dPA only modestly correlated with mean PA pressure and mean right ventricular pressure. In this group, combination of dPA used in conjunction with rPA/Ao may be a better way to predict presence of PAH noninvasively.
CLINICAL IMPLICATIONS: Clinicians should consider main PA diameter in conjunction with the rPA/Ao to help predict PAH while reviewing CT angiograms in patients with collagen vascular disorders.
DISCLOSURE: Arunabh Talwar, None.