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Atherosclerotic plaques>/=4 mm in thickness were found in 14.4 percent of the patients but in only 2 percent of the controls.After adjustment for atherosclerotic risk factors,the odds ratio for ischemic stroke among patients with such plaques was 9.1(95 percent confidence interval,3.3 to 25.2;P<0.001).Among the 78 patients who had brain infarcts with no obvious cause,28.2 percent had plaques>/=4 mm in thickness,as compared with 8.1 percent of the 172 patients who had infarcts whose possible or likely causes were known(odds ratio,4.7;95 percent confidence interval,2.2 to 10. 1;P<0.001).Plaques of>/=4 mm in the aortic arch were not associated with the presence of atrial fibrillation or stenosis of the extracranial internal carotid artery.In contrast,plaques that were 1 to 3.9 mm thick were frequently associated with carotid stenosis of>/=70 percent.These results indicate a strong,independent association between atherosclerotic disease of the aortic arch and the risk of ischemic stroke.The association was particularly strong with thick plaques.Atherosclerotic disease of the aortic arch should be regarded as a risk factor for ischemic stroke and as a possible source of cerebral emboli. |
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