Intravenous prostacyclin (as epoprostenol) infusion in thrombotic thrombocytopenic purpura. Four case reports and review of the literature. Italian Cooperative Group for Thrombotic Thrombocytopenic Purpura.

BACKGROUND: The enhanced platelet aggregation which is observed in TTP, was suggested to be due to an imbalance between unknown agents insulting endothelial wall and defense factors, such as prostacyclin (PGI2). Several reports suggested an aberration of PGI2 activity as a critical step in the pathogenesis of TTP. Therefore, PGI2 was proposed as an alternative treatment for TTP patients. METHODS: We report the results obtained with increasing doses (from 2 ng/Kg/min to 10 ng/Kg/min in 5 days) of PGI2-as epoprostenol-in 4 TTP patients from the retrospective series of the Italian Cooperative Group who were considered resistant to conventional plasma-exchange (PE)-based treatments. RESULTS: Despite PGI2 infusion, 2 patients died, while the extant 2 achieved stable complete remission. Notably, the only patient whose PE was administered with adequate frequency and for an adequate period of time, and thus the only unquestionably PE-resistant patient, was also resistant to PGI2 infusion. Major side-effects were few and observed at the highest doses. CONCLUSIONS: In our experience and from the analysis of the literature, which, as far as we know, includes only 23 patients treated with PGI2-like substances, the role of PGI2 in the treatment of TTP appears to be modest. Maybe the identification of subgroups of TTP patients exhibiting some defects in PGI2 metabolism, together with the use of more manageable PGI2 analogs, such as iloprost, could revive interest in these molecules in the future.