The frequency of aspirin and clopidogrel resistance and related factors in patients undergoing elective percutaneous coronary intervention

Abstract

Objectives: dual antiplatelet therapy with aspirin and a P2Y12 inhibitor is the mainstay of antithrombotic therapy after myocardial infarction and percutaneous coronary interventions (PCI). Despite chronic oral antiplatelet therapy, many atherothrombotic events continue to occur. Several reports in the literature have shown possible relationships between residual platelet activity and clinical outcomes, raising the possibility that “resistance” to oral antiplatelet therapy may underlie such adverse events. In this study, we aimed to determine the prevalence of aspirin and clopidogrel resistance, and related factors. We also aimed to identify the predictors of reduced antiplatelet response among patients undergoing elective PCI for stable coronary artery disease (CAD). Materials and methods: we retrospectively included patients who underwent an elective PCI with available aggregation inhibition test results. According to aggregation inhibition test results, patients were divided into two subgroups: 1-aspirin resistant/low responders and responders 2-clopidogrel resistant/low responders and responders. Results: totally 470 patients with aggregation inhibition test results (all 470 for clopidogrel and 464 for aspirin) were included in the study. Three hundred sixty-eight of them were male (78, 3%). The aspirin resistance group’s mean age was 60.8±10.3 years, the clopidogrel resistance group’s mean age was 58.89±10.1 years, and the aspirin + clopidogrel resistance group’s age was 63.25±8.8 years. Overall, there were 164 patients with single (either aspirin or clopidogrel) and 16 (3%) patients with double resistance. Hypertension, statin use, and platelet count were found as independent predictors of aspirin resistance. Hyperlipidemia, gender, and leucocyte count were found as independent predictors of clopidogrel resistance. Conclusion: 8.1% and 26.8% of stable CAD patients undergoing elective PCI showed insufficient aggregation inhibition by aspirin and clopidogrel, respectively, whereas 3% had double resistance.