Evaluation of the acute effects of inhaled iloprost on aortic compliance in pulmonary arterial hypertension using invasive methods.

BACKGROUND

Pulmonary arterial hypertension (PAH) is characterized by vascular remodeling and elevated pulmonary vascular resistance. Aortic compliance indicates vascular stiffness and may be increased in PAH. Inhaled iloprost, a prostacyclin analog, is commonly used for PAH treatment and vasoreactivity testing. Its acute effects on aortic compliance remain unclear. This study evaluated the immediate impact of inhaled iloprost on aortic compliance through aortic pulse wave velocity (aPWV) measurements and pressure parameters in patients with PAH undergoing right heart catheterization.

METHODS

This single-center, cross-sectional study enrolled patients with group 1 PAH who underwent right heart catheterization with pulmonary vasoreactivity testing between August 2022 and May 2023. Aortic compliance was measured via aPWV before and after inhaling 20 mcg/mL iloprost. On the basis of the post-iloprost changes, 32 patients were categorized into high-aPWV (n = 4) or low-aPWV (n = 28) groups. Multivariate regression analysis identified significant predictors of impaired aortic stiffness.

RESULTS

The median patient age was 54.5 years (42.2-60.5). No significant differences were found between groups regarding percentage reductions in proximal/distal aortic pressure and pulmonary artery pressure after iloprost administration. The QRS interval was a significant predictor of impaired aortic stiffness (odds ratio: 1.072, 95% confidence interval: 1.002-1.197, p = 0.045). The high-aPWV group demonstrated significantly lower QRS intervals compared to the low-aPWV group (79.0 ms [70.5-84.0] vs. 96.0 ms [85.5-102.0], p = 0.011).

CONCLUSIONS

Inhaled iloprost effectively reduced both aortic pressure and pulmonary artery pressure regardless of aortic compliance in patients with group 1 PAH. The QRS interval emerged as an independent predictor of impaired aortic stiffness, offering potential for risk stratification in clinical practice.