Right-heart catheterization is currently the gold standard method for detecting pulmonary hypertension (PH) and grading its severity. Our study determined the utility of computerized tomography (CT) scans for detecting PH in patients with left-sided heart disease, thereby potentially avoiding the overuse of invasive right-heart catheterization.A retrospective review was conducted on 40 patients with left-sided cardiac pathology who had undergone both right-heart catheterization and CT scanning of the chest. Mean pulmonary artery diameters (MPADs) were measured on CT scans and compared with pulmonary artery pressures measured by right-heart catheterization.Patients with mild-to-moderate PH had significantly greater CT-measured MPADs (34.89 ± 1.01) than patients without PH (controls) (27.36 ± 0.83, p < 0.001). Patients with severe PH had significantly greater MPADs (38.31 ± 0.88) than both mild-to-moderate PH patients (p < 0.01) and controls (p < 0.001). Receiver operating characteristic curve analysis showed that CT scanning predicted PH with an area under the curve of 0.95 (p < 0.0001). A cutoff MPAD of >33.3 mm had 100% specificity and 100% positive predictive value (N = 40, p < 0.0001), and a cutoff MPAD of <27.3 mm had 100% sensitivity with 100% negative predictive value (N = 40, p < 0.001).CT scanning correctly identified all patients with PH with MPADs >34 mm and excluded all patients without PH when MPADs were <27 mm. We advocate that the measurement of MPAD by CT scanning can be quickly and easily performed by the clinician to screen for the presence of PH.