Repetitive early stent thrombosis in a patient with the CYP2C19*3/*3 genotype.

A 45-year-old man presented with acute inferior myocardial infarction and underwent emergent coronary angiography (CAG). CAG revealed total occlusion of both the proximal right coronary artery (RCA) and distal left circumflex artery, and two bare-metal stents were deployed in the RCA. After the procedure, dual antiplatelet therapy (DAT) with 100 mg aspirin and 75 mg clopidogrel daily were given as usual, however, stent thrombosis occurred three times and he underwent repeat interventions. To investigate the cause of repeated stent thrombosis, the platelet function during DAT was measured. The result showed that he did not achieve an adequate antiplatelet effect. Clopidogrel is a prodrug that requires biotransformation by cytochrome P450 (CYP) enzyme in the liver. Recently, the carriers of CYP2C19*2 or *3 null-of-function allele, have been shown to demonstrate an increased risk of cardiovascular events, including stent thrombosis, compared with non-carriers. This patient carried the CYP2C19*3/*3 genotype. This is the first report of repetitive stent thrombosis in a poor metabolizer carrying two loss-of-function alleles (CYP2C19*3/*3).