Key result
Recent cerebral ischemia symptoms are linked to ~36% higher residual platelet aggregation versus asymptomatic patients.
Why the study?
Around 30% of patients prescribed platelet inhibitory therapy are resistant, but whether resistance to aspirin or clopidogrel associates with cerebral ischemia symptoms or pre-operative cerebral emboli in carotid endarterectomy patients was unknown.
Does antiplatelet resistance correlate with symptoms of cerebral ischemia and cerebral emboli in patients undergoing carotid endarterectomy?
Observational (n=133)
Does antiplatelet resistance correlate with symptoms of cerebral ischemia and cerebral emboli in patients undergoing carotid endarterectomy?
Absolute Event Rate: 41.9% vs 30.8%
p-value: p=0.012
Antiplatelet resistance in patients with carotid disease is significantly associated with recent symptoms of cerebral ischemia and increased frequency of cerebral emboli.
Association between resistance and symptomatic carotid disease is hypothesis-generating; should not yet alter antiplatelet strategies in practice.
Background: Platelet inhibitory therapy is prescribed to prevent arterial thromboembolism in patients with atherosclerotic disease. Although taken by millions of people, around 30% are resistant to the treatment they are being prescribed. Aims: To determine whether symptoms of cerebral ischemia, or pre-operative cerebral emboli, in patients admitted for a carotid endarterectomy were associated with resistance to aspirin or clopidogrel. Methods: Venous blood from 133 patients immediately before carotid endarterectomy (CEA) was analyzed for resistance to aspirin and clopidogrel by multiplate impedance aggregometry. The number of emboli/hour entering the ipsilateral middle cerebral artery was counted by transcranial Doppler (TCD) on the day before surgery in 33 of these patients. Results: Resistance was found in 21 (26.3%) of 100 patients taking aspirin and 14 (42%) of 33 taking clopidogrel. Mean (sd) residual platelet aggregation was significantly higher at 41.9(32) Au in patients who had suffered recent symptoms of cerebral ischemia compared with 30.8(16) Au in asymptomatic patients (p = 0.012). Residual platelet aggregation also correlated significantly with the number of emboli/hour counted by TCD in the ipsilateral middle cerebral artery (r = 0.45, p = 0.009). Conclusion: Antiplatelet resistance was associated with the frequency of cerebral emboli and recent symptoms of cerebral ischemia in patients with carotid disease. Definitive clinical studies are needed to explore whether testing for antiplatelet resistance should be undertaken routinely in patients starting platelet inhibitory therapy for cardiovascular disease.
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Ball et al. (2020) conducted an observational in Carotid artery disease (n=133). Antiplatelet therapy (aspirin or clopidogrel) vs. Asymptomatic patients was evaluated on Mean residual platelet aggregation (Au) in patients with recent symptoms of cerebral ischemia compared with asymptomatic patients (p=0.012). Residual platelet aggregation was significantly higher in patients with recent symptoms of cerebral ischemia compared to asymptomatic patients (41.9 vs 30.8 Au; p=0.012).
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