Repeated intra-stent thrombus formation in a patient with acute coronary syndrome due to poor responsiveness to clopidogrel may be associated with cytochrome P-450 2C19*2 polymorphism.

A drug-eluting stent was implanted at the culprit lesion in a 65-year-old man with acute coronary syndrome. Nine days after the procedure, he suffered stent thrombosis, and a bare-metal stent was subsequently implanted. Twelve days after this second procedure, a follow-up angiogram showed a newly emerged thrombus at the site of stent implantation. Although the patient had continued dual anti-platelet therapy with aspirin and clopidogrel since the first procedure, platelet optical aggregation test showed no inhibition of aggregation. Further, genetic analysis revealed him to be homozygous for the CYP2C192 polymorphism. This case suggests that the mechanism of stent thrombosis, while multi-factorial, is affected greatly by crossover of poor responsiveness to clopidogrel due to the CYP2C192 polymorphism.