A Multicenter Prospective observationaL Study to evAluate the effecT of Clopidogrel on the prEvention of Major vascuLar Events According to the gEnotype of Cytochrome P450 2C19 in Ischemic Stroke paTients; PLATELET Study

Clopidogrel, one of the antiplatelet agents used for secondary prevention in patients with ischemic stroke and coronary artery disease, has been shown to have a superior antiplatelet effect compared to aspirin, and is therefore being administered to many patients with stroke and coronary artery disease. Clopidogrel inhibits platelet-derived ADP receptor, P2Y12, in the liver to produce an anti-platelet effect. It has been suggested that clopidogrel resistance could be occurred from drug-drug interaction via the same pharmacological metabolic pathway. Previous studies reported that the genotypes of Cytochrome P450 2C19, which is involved in the metabolism of clopidogrel in the liver, lead to differences in drug response and recurrence rates of cardiovascular disease. The risk of recurrence of ischemic stroke was reported to be about 4 times higher in patients with a poor metabolizer or intermediate metabolizer genotype of the Cytochrome P450 2C19 genotype compared to the extensive metabolizer genotype. This genotypes of Cytochrome P450 2C19 were also different according to race.

The researches about cytochrome P450 2C19 genotype and clopidogrel resistance have been conducted mainly in patients with coronary artery disease and are not known in stroke patients. Few studies have examined whether the resistance of clopidogrel according to the genotype of cytochrome P450 2C19 in stroke patients is related to the occurrence and/or recurrence of cardiovascular disease. The hypothesis of this study is that "the poor metabolizer or intermediate metabolizer of the cytochrome P450 2C19 genotype in patients with acute ischemic stroke is associated with increased risk of cardiovascular disease and mortality compared to those who of extensive metabolizer of the cytochrome P450 2C19 genotype".