Aspirin resistance and silent brain infarcts in asymptomatic aspirin users

Background: It has been reported that aspirin resistance was correlated with severity and mortality in patients with symptomatic ischemic stroke. However, the relationship between aspirin resistance and silent stroke is unclear. Methods: From 2006 to 2009, we recruited 84 stroke-free aspirin users, including those with ischemic heart disease or atrial fibrillation. Silent brain infarcts (SBI), microbleeds (MB) and white matter hyperintensities (WMH) were determined by brain MRI. Platelet reactivity was reported as aspirin reaction unit (ARU). Aspirin resistance was defined as ARU≥550. Results: 9 (12.0%) patients had SBIs and 10 (13.3%) had MBs. Aspirin resistance was detected in 5 (6.0%) patients. Aspirin resistance, atrial fibrillation, presence of MBs and severe WMH were associated with the presence SBIs in chi-square tests (P < 0.05). ARU value was higher in patients with SBIs than those without (513.2 ± 74.0 vs. 448.4 ± 47.7, P < 0.05), which was the only significant factor after adjustment (OR 1.016, 95% CI 1.000– 1.031; P < 0.05). Patients with lower ARU value or longer duration of aspirin usage did not present with more MBs (P > 0.05). Conclusion: Aspirin resistance may be an indicator of silence brain infarcts in asymptomatic aspirin users