(HealthDay News) – In patients with acute ischemic stroke, aspirin resistance is associated with increased stroke severity and infarct size, according to research published online Nov. 19 in the Archives of Neurology.

Amy S.Y. Zheng, of the Melbourne Brain Centre in Australia, and colleagues conducted a prospective, single-center study involving 90 acute ischemic stroke patients (mean age, 75 years; 64.4% male) who had previously received aspirin therapy. They examined the association between aspirin resistance and stroke severity (measured with the National Institutes of Health Stroke Scale [NIHSS]) and infarct size (measured with the Alberta Stroke Program Early Computed Tomography Score [ASPECTS]).

The researchers identified aspirin resistance in 28.9% of the patients. In the cohort, the median aspirin reaction unit (ARU) was 486. For every one-point increase in ARU there was a significant 0.03-point increase in the NIHSS and a significant 0.02-point decrease in the ASPECTS. Every 33-point increase in ARU correlated with an approximate one-point increase in the NIHSS, while every 50-point increase in ARU correlated with a one-point decrease in the ASPECTS.

“Aspirin resistance is associated with increased clinical severity and stroke infarct volume in acute stroke patients,” the authors write. “Our results support the need for a randomized controlled study to investigate alternative antiplatelet therapy in patients with aspirin resistance.”

One author disclosed financial ties to Biometrictra, the Australian distributor of VerifyNow, the system used in the study to measure aspirin resistance.

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