Major clinical vascular events and aspirin-resistance status as determined by the PFA-100 method among patients with stable coronary artery disease: a prospective study

Aspirin inhibits platelet activation and reduces major vascular events in patients with stable coronary artery disease. The extent of platelet inhibition, denoted as aspirin resistance, however, is not always sufficient. A correlation between aspirin resistance as measured by aggregometry and adverse clinical events has been demonstrated. The point-of-care platelet function analyzer PFA-100 is usually used to detect aspirin resistance, but the relation between PFA-100 results and the vascular prognosis is not assessed. We prospectively enrolled 97 patients with stable coronary artery disease who were on aspirin (160 mg per day since 1 month or longer). Aspirin resistance was measured by the PFA-100 analyzer. Median follow-up was 2.5 years and the primary outcome was the composite of death, myocardial infarction, and ischemic cerebral infarction or acute limb ischemia. In our study, 29 patients (29.9%) showed resistance to aspirin, with a higher percentage of female patients (38 vs. 15%; P=0.01). During the follow-up, aspirin resistance was not associated with an increased risk of death, myocardial infarction, or ischemic vascular event compared with the aspirin-sensitive patients (17 vs. 13%; P>0.60). In this cohort of stable coronary artery disease, patients on aspirin dose of 160 mg per day, the aspirin-resistance status based on the PFA-100 results is not associated with a significant increase in major vascular clinical events.