Previous studies have demonstrated that platelet activation occurs in patients with pulmonary arterial hypertension (PAH). Mean platelet volume (MPV) and platelet distribution width (PDW) are two markers of platelet activation, and have recently been recognised as risk predictors of cardiovascular diseases. This study aimed to investigate whether MPV and PDW would be useful to reflect disease severity and predict prognosis in idiopathic PAH (IPAH).

MPV and PDW levels were measured in 82 IPAH patients without antiplatelet or anticoagulant treatment on admission and 82 healthy controls. Concurrent collected data included clinical, haemodynamic and biochemical variables. All patients were followed-up from the date of blood testing. The endpoint was all-cause mortality.

MPV and PDW were significantly higher in patients with IPAH than in age and sex-matched control subjects (11.4±0.9fl vs. 10.3±0.9fL and 14.3±2.9% vs. 11.9±1.9%, respectively; p=0.000). Pearson's correlation analysis revealed that MPV and PDW correlated positively with right ventricular systolic pressure, mean pulmonary arterial pressure and pulmonary vascular resistance. After a mean follow-up of 14±8 months, 12 patients died of right heart failure. Receiver operating characteristic analysis showed that MPV and PDW could not predict all-cause mortality. Multivariate Cox regression analysis suggested that right/left ventricular end-diastolic diameter ratio and NT-proBNP were independent predictive parameters of all-cause mortality.

Our results suggest that MPV and PDW were elevated in patients with IPAH. They could partly reflect disease severity, but did not predict prognosis.