The Asymptomatic Carotid Atherosclerosis Study (ACAS)

One discussion this week included the Asymptomatic Carotid  Atherosclerosis Study (ACAS).

Reference: Endarterectomy for asymptomatic carotid artery stenosis. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. JAMA. 1995 May 10;273(18):1421-1428.

Summary: ACAS was a prospective, randomized trial conducted at 39 sites in the US and Canada between December 1987 and December 1993. Its purpose was to “determine whether the addition of carotid endarterectomy to aggressive medical management can reduce the incidence of cerebral infarction in patients with asymptomatic carotid artery stenosis” (p.1421).

The primary finding was that the risk of ipsilateral stroke and any periopoerative stroke or death over 5 years was 5.1% for surgical patients and 11.0% for medically treated patients (p.1425). Furthermore, those who are good candidates for elective surgery and have carotid artery stenosis of 60% or greater reduction in diameter will have a significantly reduced 5-year risk of ipsilateral stroke “if carotid endarterecomy performed with less than 3% perioperative morbidity and mortality is added to aggressive management of modifiable risk factors” (p.1421).

Additionally, ACAS concluded that CEA reduces the relative stroke risk 66% for men and 17% for women. This difference is perhaps due to higher rates of perioperative complications in women.When arteriographic and perioperative complications are excluded, the risk reduction was 79% for men and 56% for women (p.1427).

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