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.