Background: The pulmonary vascular changes induced by epoprostenol in patients with idiopathic pulmonary artery hypertension (IPAH) have not been reported by a clinical study.
Methods and results: Analysis 1 compared the wedged pulmonary angiography (PAG) findings prior to initiation of epoprostenol therapy (n=24) with those after initiation (n=16). Analysis 2 compared the PAG findings prior to and after initiation of epoprostenol therapy (n=9) in the same pulmonary arteries in the same subjects. In analysis 1, a "cotton grass-like" stain originating from the peripheral pulmonary vessels (each vessel could not be distinguished on angiography) was not observable in any of 24 cases before initiation of epoprostenol therapy, but was visible in 13 of 16 cases after (p<0.0001). In analysis 2, the diameter of subsegmental arteries changed from 3.0+/-0.9 mm (mean +/- standard deviation) to 3.7+/-1.2 mm (p=0.004) between the 2 time periods. Cotton grass-like stain was not found in any cases before epoprostenol, but in all 9 cases after chronic use (p=0.004).
Conclusions: After initiating epoprostenol therapy, cotton grass-like stain appeared in most patients with IPAH. The possible reason for this is release of severe vasoconstriction and/or emergence of neovascularization.