Platelet membrane receptors play a key role in the pathogenesis of ischemic complications after percutaneous transluminal coronary angioplasty (PTCA) and stent implantation. Blockade of the platelet glycoprotein IIb/IIIa receptor has been shown to deminish the incidence of adverse clinical events after angioplasty. This benefit, however, is associated with a rare but profound thrombocytopenia. Changes in platelet function of patients with angina who had PTCA and coronary stent implantation and were randomized to the GPIIb/IIIa receptor antagonist abciximab (n=20) or to heparin (n=23) were evaluated using activation-dependent monoclonal antibodies and flow cytometric analysis. Abciximab application was followed by a rapid inhibition of the fibrinogen receptor and platelet activation (increased surface expression of LIBS-1, GPIIIa and P-selectin).The increased LIBS-1 surface expression correlated inversely with the decreased platelet count in the abciximab group. There was no evidence that the platelet surface changes of patients with abciximab were attributable to allelic variants of platelet polymorphisms. As compared with conventional anticoagulant therapy, abciximab leads to a rapid blockade of platelet glycoprotein IIb/IIIa receptors. Thus abciximab might close the antiplatelet therapeutic "ticlopidine window" and substantially reduce the rate of ischemic complications after coronary stenting. One might speculate that the abciximab-induced conformational changes of glycoproteins and the altered adhesive properties of circulating platelets might contribute to the development of thrombocytopenia.     «

Platelet membrane receptors play a key role in the pathogenesis of ischemic complications after percutaneous transluminal coronary angioplasty (PTCA) and stent implantation. Blockade of the platelet glycoprotein IIb/IIIa receptor has been shown to deminish the incidence of adverse clinical events after angioplasty. This benefit, however, is associated with a rare but profound thrombocytopenia. Changes in platelet function of patients with angina who had PTCA and coronary stent implantation and w...     »