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The risk of stroke from carotid stenosis is proportionate to the degree of stenosis,but whether this is a direct and linear relationship is unknown. Using the degree of carotid stenosis in 500 patients with asymptomatic carotid bruits as a continuous variable,we plotted the frequency distribution and related this to the risk of ischaemic cerebral events and the progression of the arterial lesion.There was a bi-modal distribution, with the junction of the two populations at 85%stenosis.The frequency of ischaemic cerebral events was maximal at 75-90%stenosis.Our data suggest that there is a critical degree of carotid stenosis at which stroke risk becomes maximal.This may represent a window of therapeutic opportunity. |
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