Platelet function and antiplatelet therapy in cardiovascular disease: implications of genetic polymorphisms

Platelets play a crucial role in thrombosis, inflammation, immunity and atherogenesis. Antiplatelet agents are widely used in patients with acute coronary syndrome and other cardiovascular disorders. Aspirin and clopidogrel are the most commonly prescribed antiplatelet agents, with a relatively safe profile and efficiency in a variety of clinical conditions. Numerous prospective studies have revealed variability of antiplatelet efficacy. The so called "antiplatelet resistance" prompted a search for mechanisms implicated in poor responsiveness to aspirin and clopidogrel therapy. In this regard, genetic polymorphisms in the platelet receptor genes attracted considerable interest. Specific genetic variants in platelet receptors such as the P2Y12, glycoprotein (GP) IIb/IIIa, GPIa/IIa, GPIb/IX/V and the cytochrome P450 (CYP) family of genes are associated with variable response to antiplatelet therapy and cardiovascular events. Genetic polymorphisms and haplotypes that comprehensively capture the genetic information encoded within the platelet receptor genes can, to some extent, predict response to the antiplatelet drug better than any single genotype. Genotyping for multiple receptor variants in patients on antiplatelet therapy, complemented by standardized quantification of platelet function, can provide useful information for future drug design studies and possibly for personalized antiplatelet therapy and prevention of thrombotic events. Additional information is, however, needed to evaluate the cost-effectiveness of complex genetic and platelet function testing.