A case-control study on platelet reactivity in patients with coronary stent thrombosis

Summary. Background: The pathophysiology of stent thrombosis (ST) has evolved from the identification of single causative factors to a complex multifactorial model. Objectives: The aim of the present study was to investigate whether patients with a history of ST exhibit heightened platelet reactivity to clopidogrel and aspirin. Patients/methods: Pretreatment and on-treatment platelet reactivity to clopidogrel and aspirin, as well as dual antiplatelet therapy resistance, was determined in 84 patients with a history of definite ST (cases: 41 early ST; 43 late ST) and in 103 control patients with a previously implanted coronary stent but no ST after the index procedure. Platelet function was evaluated with optical aggregometry, the VerifyNow P2Y12 and aspirin assays, the PFA-100 Innovance P2Y* cartridge, the flow cytometric vasodilator-stimulated phosphoprotein assay and urine 11-dehydrothromboxane B2 measurement before and after the administration of a 600-mg loading dose of clopidogrel and 100 mg of aspirin. The study was registered at ClinicalTrials.gov, number NCT01012544. Results: Patients with a history of early ST clearly demonstrated higher on-clopidogrel platelet reactivity than controls. Patients with both early and late ST exhibited heightened on-aspirin platelet reactivity status, and dual antiplatelet therapy resistance was more frequent. Conclusions: Patients with a history of early ST exhibit a poor response to clopidogrel. Furthermore, both early and late ST are strongly and independently associated with heightened on-aspirin platelet reactivity, and dual antiplatelet therapy resistance is more frequent.