The role of platelet glycoprotein IIIa polymorphism in the high prevalence of in vitro aspirin resistance in patients with intracoronary stent restenosis

Objectives The aim of our study was to determine the relation between platelet glycoprotein Illa (pl(A)) polymorphism and aspirin resistance in patients with intracoronary stent restenosis. Background Clinically, aspirin resistance is defined as having thrombotic and embolic cardiovascular events despite regular aspirin therapy. Platelet glycoprotein Illa polymorphism is said to be a possible mechanism of aspirin resistance. Methods We studied the prevalence of aspirin resistance in 204 previously intracoronary stent-implanted patients with stable coronary artery disease. In 102 of these patients, intracoronary stent restenosis was present. Platelet functions were analyzed in a platelet function analyzer (PFA-100, Dade Behring, Germany) with collagen and/or epinephrine (Col/Epi) and collagen and/or adenosine diphosphate cartridges. Closure time <186 seconds was defined as aspirin resistance with Col/Epi cartridges of PFA-100. The pl(A) polymorphisms of 43 aspirin-resistant and 51 aspirin-sensitive subjects were determined with polymerase chain reaction and restriction fragments length polymorphism. Results A total of 31.3% (n = 32) of patients with intracoronary stent restenosis and 10.7% (n = 11) of patients with patent intracoronary stents were resistant to aspirin by PFA-100. The pl(A1,A1) allele of glycoprotein Illa was present in 36 subjects (83.7.%) and the pI(A1,A2) allele was present in 7 subjects (16.2.%) in the aspirin-resistant patients group. The pl(A1,A1) allele of glycoprotein Illa was present in 37 subjects (72.5%) and the pl(A1,A2) allele was present in 14 subjects (27.5%) in the aspirin-sensitive patients group (P =.195). Conclusion Our results suggest that platelets of patients with intracoronary stent restenosis with or without pl(A2) heterozygosity of glycoprotein Illa are more likely to be resistant to low-dose aspirin therapy.