OBJECTIVE To evaluate how pulmonary artery (PA) distensibility performs in detecting pulmonary hypertension due to left heart disease (PH-LHD) in comparison with parameters from ungated computed tomography (CT) and echocardiography. METHODS One hundred patients (79 men, mean age = 63 ± 17 years) with either severe heart failure with reduced ejection fraction (HFrEF), aortic stenosis, or primary mitral regurgitation prospectively underwent right heart catheterization, ungated CT, ECG-gated CT, and echocardiography. During the ECG-gated CT, the right PA distensibility was calculated. In ungated CT, dPA, dPA/AA, the ratio of dPA to the diameter of the vertebra, segmental PA diameter, segmental PA-to-bronchus ratio, and the main PA volume were measured; the egg-and-banana sign was recorded. During echocardiography, the tricuspid regurgitation (TR) gradient was measured. The areas under the ROC curves (AUC) of these signs were computed and compared with DeLong test. Correlation between PA distensibility and PA pressure (PAP) was investigated through Pearson's coefficient. RESULTS PA distensibility was lower in patients with PH than in those without PH (11.4 vs. 21.2%, p < 0.001) and correlated negatively with mean PAP (r = - 0.72, p < 0.001). Age, PA size, and mean PAP were independent predictors of PA distensibility. PA distensibility < 18% detected PH-LHD with 96% sensitivity and 73% specificity; its AUC was 0.92, larger than that of any other sign at ungated CT and TR gradient (AUC ranging from 0.54 to 0.83, DeLong: p ranging from 0.020 to < 0.001). CONCLUSIONS PA distensibility on an ECG-gated CT can detect PH-LHD better than the parameters reflecting PA dilatation in ungated CT or TR gradient in the echocardiography of patients with severe HFrEF, aortic stenosis, or mitral regurgitation. CONCLUSIONS • In left heart disease, pulmonary artery distensibility is lower in patients with PH than in those without pulmonary hypertension (11.4 vs. 21.2%, p < 0.001). • In left heart disease, pulmonary artery distensibility detects pulmonary hypertension with an area under the receiver operating curve of 0.92. • In left heart disease, the area under the receiver operating curve of pulmonary artery distensibility for detecting pulmonary hypertension is larger than that of all other signs at ungated CT (p from 0.019 to < 0.001) and tricuspid regurgitation gradient at echocardiography (p = 0.020).