WASHINGTON, DC—Individuals who exhibit a resistance to aspirin may be more likely to have more severe strokes than people who still respond to the drug, according to a study presented at the American Academy of Neurology’s 67th Annual Meeting. The study also found that in those with aspirin resistance, the actual size of their stroke appears larger.
Prior aspirin use has been associated with lower stroke severity and decreased infarction growth. However, a percentage of patients may be resistant to aspirin, which in turn may negate the aspirin’s effect of lowering stroke risk. The concept of “resistance” to aspirin has been controversial, and the testing of resistance varies between studies.
“Eventually, we may be able to identify people who are likely to be resistant to aspirin and give them higher doses or different drugs to prevent blood clots,” said study author Mi Sun Oh, MD, from Hallym University College of Medicine in Chuncheon, South Korea. “However, we need better ways to identify people with aspirin resistance before any changes can be made. For now, people who are taking low-dose aspirin to prevent blood clotting and stroke should continue to do so.”
The study involved 310 people who had an ischemic stroke and had been taking aspirin for at least seven days before the first stroke symptoms. A total of 86 people, or 27.7%, were resistant to aspirin in this study. In the aspirin-resistant group, the median stroke severity score was four, with scores ranging from three to 11, where scores from one to four indicate a minor stroke and scores from five to 15 indicate a moderate stroke. For those who responded to aspirin, the average stroke severity score was three, with scores ranging from one to six.
Patients who were aspirin resistant also had larger areas of the brain affected by the stroke, as measured by MRI diffusion-weighted imaging (DWI). Median DWI infarction volume was larger in the aspirin-resistant patients (2.8 cc) compared with aspirin responders (1.6 cc).
The study was supported by a grant of the Korea Healthcare Technology R&D project, Ministry of Health and Family Welfare, and the Republic of Korea.