Prevalence and progression of internal carotid artery stenosis in patients with peripheral arterial occlusive disease
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OBJECTIVE: The purpose of this study was to determine the prevalence of significant carotid stenosis, to identify risk factors increasing this prevalence, and to determine the risk of progression of stenosis, in patients with peripheral arterial occlusive disease who are neurologically asymptomatic. STUDY DESIGN: Consecutive patients who underwent evaluation in a vascular laboratory for peripheral arterial occlusive disease, who had no recent neurologic symptoms, were investigated. RESULTS: From July 1999 to December 2000, 620 patients underwent duplex scanning on one occasion, and 417 on two occasions. The average age was 72 +/- 10 years, and 61% were men. An occluded internal carotid artery was found in 4.8% of patients. The prevalence of a carotid stenosis >50% was 33% on the initial evaluation. Age of more than 70 years (P =.007), diabetes mellitus (P =.042), history of stroke (P =.011), and ankle/brachial index of less than 0.8 (P =.0006), were independently associated with carotid stenosis >50%. The odds ratio associated with each of these risk factors was similar. The prevalence of carotid stenosis >50% was 16%, 21%, 38%, 47%, and 44% for patients with no, one, two, three, and four risk factors, respectively. The highest prevalence of carotid stenosis >50% was identified in patients with ankle/brachial indices of less than 0.4 (59%). During the follow-up period, no patient had a cerebrovascular event. In 15% of carotid arteries, progression from one class of stenosis to a more severe class was observed, and 6.5% of patients progressed from a lower degree to 50% to 99% stenosis. No differences in progression of disease were identified when the variables of age, diabetes, previous stroke, and ankle/brachial index of less than 0.8 were studied or when patients with zero to two of these putative risk factors were compared with patients with three or four. CONCLUSION: Screening for carotid stenosis in asymptomatic patients with peripheral vascular disease is justifiable, but not mandatory, when two or more risk factors are present or when the ankle/brachial index is less than 0.4. Rates of progression to clinically significant stenosis are low and do not justify reevaluation every 6 months. Further research to identify the optimal interval for reevaluation is needed.
