The Application of Intravascular Ultrasound to Evaluate Pulmonary Vascular Properties and Mortality in Patients with Pulmonary Arterial Hypertension

Background: The aim of this study was to explore the application of intravascular ultrasound (IVUS) to evaluate pulmonary vascular properties and mortality in patients with pulmonary arterial hypertension (PAH). Methods: Patients (n = 51) with systolic pulmonary artery pressures >= 40 mm Hg on echocardiography were prospectively enrolled. All patients underwent right-heart catheterization and IVUS and were divided into three groups: PAH associated with connective tissue diseases (group 1, n = 25), PAH due to other causes (group 2, n = 15), and patients with connective tissue diseases without pulmonary hypertension (group 3, n = 11). PAH groups (groups 1 and 2) were divided into distal (n = 22) and proximal (n = 18) remodeling subtypes on the basis of IVUS results. All patients were followed (19 6 10 months) to compare the differences among clinical variables, pulmonary vascular properties, and survival rates. Results: A total of 408 segments of pulmonary arteries were studied. The PAH groups demonstrated a greater mean wall thickness than group 3 (P < .01 for all). Pulmonary vascular mechanical properties, including compliance, distensibility, elastic modulus, and stiffness index beta, were found to be worse in the PAH groups than in group 3 (P < .01 for all), but they tended to be better in group 1 than in group 2. An inverse exponential association was found between pulmonary vascular mechanical properties and hemodynamics, with R 2 values ranging from 0.54 to 0.78 (P < .001). In the PAH groups, the mortality in group 1 was similar to that in group 2 (12% vs 13%, P > .05), while the distal remodeling subtype had higher mortality than the proximal remodeling subtype (23% vs 0%, P < .05). Conclusions: IVUS is useful in PAH assessment by evaluating pulmonary vascular properties and predicting mortality. The classification of the proximal and distal remodeling type of PAH may be proposed to predict mortality and evaluate the prognosis of patients with PAH in clinical practice.