Attenuation of platelet reactivity by enoxaparin compared with unfractionated heparin in patients undergoing haemodialysis

BACKGROUND: Increased platelet reactivity presages adverse cardiac events. Because both haemodialysis and unfractionated heparin (UFH) can increase platelet reactivity, we compared platelet reactivity during haemodialysis when patients were anticoagulated with UFH or enoxaparin. METHODS: Patients (n = 20) underwent consecutive haemodialysis sessions with either UFH or enoxaparin in a random order. Blood was taken from the arterial end of the haemodialysis circuit at the initiation of haemodialysis before anticoagulation. Subsequently, blood was taken during dialysis from the venous end of the circuit 10 min after treatment with UFH or enoxaparin. Platelet reactivity was assessed with the use of flow cytometry by determining the capacity of platelets to bind fibrinogen and the surface expression of P-selectin in response to adenosine diphosphate (ADP, 0 and 0.2 microM). Results were compared with the use of two-way repeated measure ANOVA. RESULTS: Platelet reactivity in arterial blood obtained at the beginning of dialysis prior to patients being treated with either UFH [0.2 microM ADP-induced capacity to bind fibrinogen = 28+/-15% (SD)] or enoxaparin (30+/-18%) was similar (P = 0.15). In contrast, platelet reactivity was less after treatment with enoxaparin compared with UFH (P = 0.006). The 0.2 microM ADP-induced capacity to bind fibrinogen in venous blood obtained 10 min after anticoagulation was 34+/-11% after treatment with UFH and 22+/-11% after treatment with enoxaparin. CONCLUSIONS: Anticoagulation with enoxaparin during haemodialysis is associated with less platelet reactivity compared with UFH. Accordingly, enoxaparin use may contribute to a lesser risk of cardiac events in patients with end-stage renal disease treated with haemodialysis.