Noninvasively assessed pulmonary artery stiffness predicts mortality in patients with pulmonary arterial hypertension (PAH), according to Dutch researchers.

"Right ventricular load is not only confined to pulmonary vascular resistance but also to compliance," senior investigator Dr. Anton Vonk-Noordegraaf told Reuters Health. "A reduction in pulmonary vascular compliance will increase right ventricular load, which is related to an increased mortality. Although compliance can only be assessed invasively, distensibility of the pulmonary vascular bed is an important determinant of compliance."

In the December issue of Chest, Dr. Vonk-Noordegraaf and colleagues at VU University Medical Center, Amsterdam note that they studied 86 patients to investigate whether a measure of proximal pulmonary artery stiffness -- area distensibility and relative cross-sectional area change (RAC) via MRI -- might be of use in predicting mortality. The patients underwent right heart catheterization and MRI.

In 70 patients, PAH was confirmed and the remaining 16 subjects acted as controls. Compared to controls, the patients showed significantly less area distensibility and lower RAC of the pulmonary artery. RAC also showed an inverse curvilinear relationship with mean pulmonary artery pressure.

The participants were followed for up to four years. Eighteen patients (26 per cent) died of cardiopulmonary causes, and the team found that those with a pulmonary artery RAC below 16 per cent were significantly less likely to survive than those with a higher value.

In addition, RAC predicted mortality better than did area distensibility and also did so independently of pulmonary artery pulse pressure.

"This study," continued Dr. Vonk-Noordegraaf, "shows that noninvasive measurement of the distensibility characteristics of the pulmonary artery is a strong prognostic marker in pulmonary hypertension, emphasizing the fact that although the disease is in the small vessels, the large vessels contribute significantly to right ventricular load."

Future studies, the investigators conclude, "may elucidate the predictive value of noninvasively assessed RAC, not only with established predictors of mortality in PAH but with noninvasively assessed parameters of right ventricular structure and function."