Pulmonary artery distensibility index is a non-invasive useful marker of pulmonary arterial hypertension progression.

ulmonary arterial hypertension (PAH), defined as a mean pulmonary arterial pressure greater than 25 mmHg at rest detected by right heart catheterization (RHC),1,2 is a fatal disease caused by small pulmonary artery obstruction as a result of vascular proliferation and remodeling.3,4 PAH is characterized by markedly elevated pulmonary artery pressure and increased pulmonary vascular resistance (PVR), frequently leading to right-sided heart failure and death.3,4 The pathophysiological changes of the pulmonary arteries in PAH include endothelial injury, proliferation, and hypercontraction of vascular smooth muscle cells, migration of inflammatory cells, and activation of several intracellular signaling pathways such as Rho-kinase pathway.3,5–7