Platelet abnormalities in adults with severe pulmonary arterial hypertension related to congenital heart defects (Eisenmenger syndrome)

Patients with severe pulmonary arterial hypertension suffer from life-threatening thrombotic and bleeding complications. The aim of this study was to compare selected platelet, endothelial, and coagulation parameters in healthy volunteers and patients with severe pulmonary arterial hypertension because of congenital heart defects. The study included healthy volunteers (n=50) and patients with cyanotic congenital heart defects classified as Eisenmenger syndrome (n=41). We investigated platelet count, mean platelet volume, and platelet aggregation - spontaneous and induced by various concentrations of five agonists. Von Willebrand factor (vWF), fibrinogen, factor VIII and XII, plasminogen activator inhibitor, antithrombin, D-dimer, and antiphospholipid antibodies were also investigated. We found a decreased platelet count [190 (147-225) vs. 248 (205-295) 10(9)l(-1), P<0.0001], higher mean platelet volume [10.9 (10.1-12.0) vs. 10.2 (9.4-10.4)fl, P<0.0001], and significantly decreased platelet aggregation (induced by five agonists, in various concentrations) in patients with Eisenmenger syndrome compared with controls. These changes were accompanied by an increase of plasma vWF antigen [141.6 (108.9-179.1) vs. 117.4 (9.2-140.7)IU/dl, P=0.022] and serum anti-(2)-glycoprotein [2.07 (0.71-3.41) vs. 0.47 (0.18-0.99)U/ml, P<0.0001]. Eisenmenger syndrome is accompanied by platelet abnormalities. Thrombocytopenia with increased platelet size is probably due to a higher platelet turnover associated with platelet activation. Impaired platelet aggregation can reflect specific platelet behaviour in patients with Eisenmenger syndrome. These changes can be related both to bleeding and to thrombotic events. A higher vWF antigen may be a consequence of endothelial damage in Eisenmenger syndrome, but the cause for an increase of anti-(2)-glycoprotein is unknown.