Tuesday, January 22, 2008

Screening for Carotid Artery Stenosis: An Update of the Evidence for the U.S. Preventive Services Task Force

Screening for Carotid Artery Stenosis: An Update of the Evidence for the U.S. Preventive Services Task Force

American College of Cardiology
Journal Scan

Ann Intern Med. 2007 Dec 18;147(12):860-70.

Perspective: The following are 10 points to remember about screening for carotid artery stenosis.

1. Cerebrovascular disease is the third leading cause of death in the United States and ~500,000 people experience their first stroke annually.

2. There has been a 70% decline in mortality from cerebrovascular disease in the United States since 1950. This is primarily related to reduction in smoking and better management of hypertension.

3. Almost 88% of strokes are ischemic in nature, and of these, 20% are due to large artery stenosis.

4. A stenosis severity of greater than 50%-60% is considered clinically important because these lesions have been associated with an increased risk of stroke.

5. The prevalence of clinically important asymptomatic carotid artery stenosis is estimated to be <1% in the general primary care population and ~1% in the population ≥65 years of age.

6. Carotid endarterectomy (CEA) is highly effective at reducing risk of subsequent stroke in patients who have had a transient ischemic attack or a minor stroke and have an ipsilateral severe carotid artery stenosis.

7. Duplex ultrasonography has high sensitivity and specificity (over 90%) for detecting severe carotid artery stenosis. Both computed tomography angiography and magnetic resonance angiography have similar accuracy for detection of severe asymptomatic carotid artery stenosis.

8. In selected patients undergoing CEA for severe asymptomatic carotid artery stenosis by select surgeons, the 5-year risk of stroke was reduced from 11.8 % to 6.4% with surgery. The perioperative risk of death or stroke was 3.1%. About half of the strokes prevented by surgery are disabling.

9. The outcome of patients undergoing CEA outside of clinical trials is variable with a stroke and death rate that has ranged from 2.3% to 3.7%, although rates as high as 6% have been reported. The incidence of periprocedural myocardial infarction varies from 0.7% to 1.1% in most published series, and may be higher because routine screening for asymptomatic myocardial infarction is uncommon.

10. No study has evaluated the benefit of screening for asymptomatic carotid artery stenosis. Assuming a prevalence of 1% in people over 65 years of age and a sensitivity of 94% and a specificity of 92% for ultrasonic screening and a perioperative death or stroke rate of 3.1%, 4,348 people would need to be screened to prevent one stroke, and 8,696 people would need to be screened to prevent one disabling stroke.

Routine screening for carotid artery stenosis is currently not recommended. Hitinder S. Gurm, M.B.B.S., F.A.C.C.

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