Acute thrombosis of everolimus-eluting platinum chromium stent caused by impaired prasugrel metabolism due to cytochrome P450 enzyme 2B6*2 (C64T) polymorphism: a case report

BACKGROUND: Dual antiplatelet therapy with aspirin and P2Y12 receptor inhibitor is an important option for preventing acute stent thrombosis after percutaneous coronary intervention (PCI). CASE SUMMARY: A 72-year-old man was admitted to our hospital with ST-segment elevation myocardial infarction. Emergent coronary angiography identified the occlusion in the proximal left anterior descending artery. This lesion was successfully treated by thrombus aspiration and an everolimus-eluting platinum chromium stent implantation with loading of aspirin 200 mg and prasugrel 20 mg. However, acute closure of the stent occurred 1 h after PCI. P2Y12 reaction units (PRU) measured using VerifyNow assay was 282, suggesting high platelet reactivity on prasugrel. After adding cilostazol 200 mg, recanalization was successfully obtained by thrombus aspiration and ballooning under intra-aortic balloon pump. Thereafter, PRU decreased to 266 at 4 h after PCI, and 49 the next day, implying full inhibition of platelet reactivity on prasugrel. Fortunately, no stent thrombosis has recurred since then. Genotype analysis of cytochrome P450 enzyme (CYP) demonstrated CYP2B6*1/*2 polymorphism leading to impaired metabolism of prasugrel. Based on these findings, acute stent thrombosis in the present case might have been caused by delayed expression of prasugrel effects due to CYP2B6*2 (C64T) polymorphism. DISCUSSION: In cases of stent thrombosis, we should consider the possibility of poor response to P2Y12 receptor inhibitors due to CYP polymorphism. Assessment of platelet aggregation and CYP genotype may be warranted.