Acas Carotid Trial
Purpose: Since the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the Asymptomatic Carotid Artery Stenosis Study (ACAS) established the efficacy of carotid endarterectomy at large academic centers, there have been two community-based studies of outcomes after this operation. The purpose of this study was to perform a statewide survey to evaluate postoperative morbidity and mortality after carotid. Between 1993 and 2003, ACST randomized 3120 patients with 60% mainly asymptomatic carotid stenosis (12% had symptoms at least 6 months previously) to immediate endarterectomy plus medical treatment versus medical treatment alone or until the operation became necessary. 17 Surgeons were required to provide evidence of an operative risk of ≤6% for their last 50.
Perspective:
The following are 10 points to remember about asymptomatic carotid stenosis:
1. With modern intensive medical therapy, the risk of stroke in patients with asymptomatic carotid stenosis is now much lower than it was when the earlier trials, ACAS (Asymptomatic Carotid Atherosclerosis Study) and ACST (Asymptomatic Carotid Stenosis Trial), were conducted.
2. In contrast to symptomatic carotid stenosis, in asymptomatic carotid stenosis, the severity of stenosis does not predict risk.
3. It is disturbing that in the United States, the indication for approximately 90% of carotid endarterectomy and stenting is asymptomatic carotid stenosis based on extrapolation from CREST (Carotid Revascularization Endarterectomy Versus Stenting Trial), a modern study of stenting versus endarterectomy without a medical arm of therapy, to historical results from the medical arms of early studies of carotid endarterectomy, which were performed during a time when medical therapy was much less effective.
4. This extrapolation is not valid, because with modern medical therapy, the risk of stroke in patients with asymptomatic carotid stenosis is much lower than it was in the two historical trials that are used to justify this practice.
5. The risks of stroke or death in CREST cannot legitimately be used to justify stenting or endarterectomy in unselected patients with asymptomatic carotid stenosis.
6. Transcranial Doppler embolus detection may identify the 10% of patients who would be at high enough risk to benefit from endarterectomy or stenting.
7. Additional indications of high-risk asymptomatic carotid stenosis include ulceration of carotid plaques on three-dimensional carotid ultrasound, intraplaque hemorrhage on magnetic resonance imaging, and echolucency of carotid plaques.
8. We need randomized controlled trials with a medical arm that compares stenting, endarterectomy, and modern intensive medical therapy in patients with asymptomatic carotid stenosis to assess true safety/efficacy of revascularization.
9. The proposed CREST-2 trial proposes exactly that comparison.
10. With asymptomatic carotid stenosis, patients clearly warrant intensive medical therapy to reduce their high risk of coronary events in addition to their risk of stroke.
Clinical Topics:Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Vascular Medicine, Interventions and Imaging, Interventions and Vascular Medicine, Magnetic Resonance Imaging
Keywords:Stroke, Endarterectomy, Carotid, Carotid Artery Diseases, Constriction, Pathologic, Embolism, Carotid Stenosis, Magnetic Resonance Imaging, United States, Stents
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Acas Carotid Trial Meaning
