The effect of iloprost infusion on platelet function in patients with peripheral vascular disease

The present study investigates platelet function after intermittent iloprost infusion (for 3 days) in patients with severe peripheral vascular disease (PVD). When all patients were considered, there was a significant increase in whole blood and platelet rich plasma (PRP) platelet count following the infusion of iloprost. Significant hyperaggregability occurred only in the patients who had a considerable (> 50%) increase of PRP platelet count after the infusion of iloprost. Patients who had small changes PRP platelet counts (± 20%) showed a significant inhibition of platelet aggregation at the end of the iloprost infusions. When all patients were considered, the platelet yield (PRP platelet count/whole blood platelet count) increased significantly after the iloprost infusions. There were no significant changes in platelet yield, platelet count or aggregation when these patients received placebo infusions. The present findings suggest that a fall in platelet count occurs, in vitro, during the preparation of PRP from PVD patients with hyperaggregable platelets. This in vitro effect is diminished after the infusion of iloprost resulting in an increase in the number of active platelets, and consequently hyperaggregability, in the PRP. These findings may account for the previously observed paradoxical prolongation of platelet life-span despite rebound hyperaggregability following PGI₂ infusions.