Microembolic Signals and Aspirin Resistance in Patients with Carotid Stenosis

Introduction and Aims Aspirin resistance may be linked to increased risk of cardiovascular events. We aimed to evaluate whether it was associated with presence of microembolic signals (MES), a readily measurable marker of increased stroke risk, in those with internal carotid artery (ICA) disease. Methods We studied patients with significant ICA disease who were compliant with aspirin therapy. We performed monitoring for MES and measured aspirin resistance status, using the platelet function analyzer (PFA)-100 and Verify-Now systems. We compared frequency of aspirin resistance between patients with and without MES and assessed agreement between the different platelet function tests. Results We recruited 62 patients. Most (53, 85.5%) had symptomatic carotid disease and 16 (25.8%) had MES. The rate of aspirin resistance on at least one test was 25.8% (16 patients), with 13 (21%) resistant on PFA-100 testing, 8 (12.9%) using the Verify-Now system and 5 (8.1%) resistant on both. Aspirin resistance was more common in patients with MES (50% compared to 17.4% without, P= 0.018 on Fisher's exact test). Agreement between the platelet function tests was moderate (?= 0.41). Conclusion Aspirin resistance appears more common in patients with carotid disease who have MES compared to those without. Further work should aim to establish whether screening for aspirin resistance and subsequent adjustment to antiplatelet therapy reduces the rate of MES and stroke risk in those with carotid disease.