A pilot study of resistance to aspirin in stroke patients.

Aspirin resistance has been shown to be a significant risk factor for recurrent cardiovascular ischaemic events. However, there are a lack of data correlating aspirin resistance and risk of cerebrovascular ischaemic events. This pilot study aimed to determine the prevalence of aspirin resistance in an Australian stroke population and to correlate aspirin resistance with an increased risk of ischaemic stroke. Fifty patients treated with aspirin for 2 years were tested for aspirin resistance using the Ultegra Rapid Platelet Function Assay (Accumetrics, San Diego, CA, USA) on admission to Royal Melbourne Hospital for ischaemic stroke. The 2-year history of ischaemic stroke and transient ischaemic attack (TIA) were assessed. Prevalence of aspirin resistance among our patients was 30%. Univariate analysis suggested a non-significant trend towards increased rate of previous ischaemic stroke or TIA and aspirin resistance (odds ratio, OR=3.88; 95% confidence interval 0.54-29.87; p=0.18). This study shows that aspirin resistance is prevalent within the Australian ischaemic stroke population.