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Link Between Aspirin Resistance and Stroke Print E-mail
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ศุกร์, 15 มีนาคม 2013

Laurie L. Barclay, MD
Mar 06, 2013
Association of Aspirin Resistance With Increased Stroke Severity and Infarct Size
Zheng AS, Churilov L, Colley RE, Goh C, Davis SM, Yan B

JAMA Neurol. 2013;70:208-213
Aspirin Resistance and Stroke
Aspirin resistance, or the inability to reduce thromboxane A2 levels after aspirin therapy, is linked to increased risk for recurrent stroke and poor outcomes after stroke. It could, therefore, result in a significant increase in health burden.
Study Summary
The goal of this prospective, single-center survey study was to examine the association between aspirin resistance and clinical and neuroimaging measures of stroke severity in patients with acute ischemic stroke who were treated with aspirin. At the Royal Melbourne Hospital in Parkville, Victoria, Australia, investigators enrolled 90 patients with acute stroke who had previously received aspirin therapy.
The mean age of the participants was 75 years (+/- 9.9 years) and 64.4% were men. The median National Institutes of Health Stroke Scale (NIHSS) score, which measures clinical stroke severity, was 4 (interquartile range [IQR], 3-10). Using the Alberta Stroke Program Early CT Score (ASPECTS), the median stroke infarct size was 9 (IQR, 6-10).
More than one fourth (28.9%; 95% confidence interval [CI], 0.19-0.38) of all patients had aspirin resistance, measured with the VerifyNow® system (Accumetrics; San Diego, California). The median aspirin reaction unit (ARU) was 486.0 (IQR, 432.3-557.0). Every 1-point increase in ARU was associated with a 0.03-point increase in NIHSS score (95% CI, 0.01- 0.04; P < .001) and a 0.02-point reduction in ASPECTS (95% CI, -0.03 to -0.01; P < .001). This yielded approximately a 1-point median increase in NIHSS score for every 33-point increase in ARU or a 1-point reduction in ASPECTS for every 50-point increase in ARU.
Viewpoint
The limitations of this study include small sample size, slight selection bias for patients with relatively milder symptoms, and possible insensitivity of ASPECTS for early ischemic changes. Nonetheless, it appears that in patients with acute stroke, aspirin resistance is associated with increased clinical severity and stroke infarct volume. The findings warrant a randomized controlled trial of alternative antiplatelet therapy in patients with aspirin resistance.
Abstract
Medscape Neurology © 2013 WebMD, LLC
Cite this article: Laurie L. Barclay. Link Between Aspirin Resistance and Stroke. Medscape. Mar 06, 2013.

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