Vascular compliance phenotyping in pulmonary arterial hypertension (a PVDOMICS study)

Pulmonary arterial compliance is reduced in pulmonary arterial hypertension and may be a valuable prognostic marker; however, little is known about phenotypic factors or how compliance correlates with a range of outcomes. Our objective was to identify factors associated with compliance and evaluate relationships between compliance, cardiac morphology, exercise metrics, and mortality for individuals with pulmonary arterial hypertension and otherwise similar resistive afterload.

We analyzed data from adult participants of the PVDOMICS cohort with World Symposium Group 1 pulmonary arterial hypertension. Compliance was derived by right heart catheterization measurement of stroke volume divided by pulmonary artery pulse pressure. Linear regression and Cox proportional hazards were used to estimate associations with outcomes in staged models.

In the cohort study population of 328 participants, several factors were associated with worse pulmonary arterial compliance, including older age, shorter time since diagnosis, higher pulmonary arterial wedge pressure, and connective tissue disease-associated pulmonary arterial hypertension. These associations persisted among individuals with otherwise similar pulmonary vascular resistance. Compliance was also associated with cardiac magnetic resonance-derived right ventricular morphology and exercise tolerance. There was a protective association between compliance and death or transplant, particularly among those with a mean pulmonary artery pressure ≤40 mmHg (HR = 0.44 per 1 mL/mmHg better compliance [95% CI 0.24, 0.82], p = 0.009).

Pulmonary arterial compliance is associated with several patient factors, right heart adaptation, exercise tolerance, and survival. Future studies are needed to investigate the role of compliance in the pathophysiology of connective tissue disease-associated pulmonary arterial hypertension, risk stratification, and endotypes of disease.