Abnormal platelet aggregation in pediatric pulmonary hypertension

Endogenous prostacyclin stimulates pulmonary vasodilation and inhibits platelet aggregation. For the synthetic analog treprostinil, used in the treatment of pulmonary hypertension (PH), conflicting, anecdotal evidence exists regarding its effects on clinically relevant platelet function. This study investigated whether treprostinil therapy results in inhibition of platelet aggregation in pediatric PH patients. This is a single institution, prospective, cohort study. Pediatric patients ≤18 years of age on medical therapy for PH underwent platelet function testing by light transmission aggregometry with U‐46619—a stable analog of endoperoxide prostaglandin H(2), exhibiting properties similar to thromboxane A2 (TXA2). Results were compared for those on continuous treprostinil therapy (TRE) versus those on other, non‐prostacyclin therapies (non‐TRE). Thirty‐five patients were enrolled: 18 in the TRE group and 17 in the non‐TRE group. There was no difference in platelet aggregation abnormalities between the two groups: 44% (n = 8) in the TRE group and 41% (n = 7) in the non‐TRE group were abnormal. Furthermore, subgroup analysis showed no difference based on treprostinil dosing. This study demonstrated similar, moderately high rates of abnormal platelet aggregation in pediatric PH patients on continuous treprostinil therapy compared to those on other, non‐prostacyclin therapies. The high rate of abnormal platelet aggregation in the entire cohort, however, warrants follow‐up study to identify a potential inherent risk in this population.