NASCET

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Barnett HJ, et al. "Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis". The New England Journal of Medicine. 1998. 339(20):1415-25.
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Clinical Question

In patients with symptomatic stenosis, does CEA reduce risk of death or stroke?

Bottom Line

CEA reduces the 5-year risk of death or stroke by 29% among patients with symptomatic high-moderate (50-69%) carotid stenosis.

Major Points

Prior studies had demonstrated the benefit of carotid endarterectomy (CEA) in patients with severe carotid stenosis, but NASCET was the first large, well-designed trial to study CEA in patients with low-moderate (<50%), high-moderate (50-69%), and severe (≥70%) stenosis. Those with symptomatic 50-69% stenosis had a 29% reduction in the 5-year risk of death or stroke, while those with <50% stenosis had no such benefit. Those with ≥70% stenosis received such a dramatic benefit that this study arm was prematurely stopped and all patients with severe stenosis were subsequently referred for CEA.

Guidelines

  • The 2005 American Academy of Neurology guidelines[1] make the following recommendations:
    • CEA if symptomatic in previous 6 months and 70-99% stenosis (level A)
    • CEA consideration if symptomatic and 50-69% stenosis (level B)
    • No consideration for CEA if symptomatic and <50% stenosis (level A)

Design

  • Multicenter, parallel-group, randomized controlled trial
  • N=2,226
    • CEA (n=1,108)
    • Medical therapy (n=1,108)
  • Setting: 106 centers worldwide
  • Enrollment: 1987-1990
  • Mean follow up: 5 years

Population

Inclusion Criteria

  • Symptomatic stenosis <70% in ipsilateral internal carotid artery imaged within 180 days
    • TIA or nondisabling stroke (Rankin score <3) were considered symptoms of stenosis
    • Stenosis assessed on selective angiography
      • Minimum 2 projections showing cervical and intracranial carotid arteris and major branches
      • Ipsilateral atheromatous stenosis must be >30%, <100%, and be technically suitable for CEA
  • CT head, carotid doppler US, and CXR required

Exclusion Criteria

  • Age >80 years (excluded in first phase only)
  • Lack of angiographic evidence of ipsilateral stenosis
  • Intracranial stenosis more clinically significant than cervical lesion
  • Other lesion limiting life expectancy to <5 years
  • Cerebral infarction eliminating useful function in affected vascular distribution
  • Nonatherosclerotic carotid disease
  • Carotid lesions likely to cause cardioembolism
  • History of ipsilateral endarterectomy

Interventions

  • Study divided into two phases
    • First phase: moderate/severe stenosis
    • Second phase: moderate stenosis alone
  • Randomized to CEA or medical therapy
    • Patients with moderate stenosis who progressed to severe stenosis were offered endarterectomy
  • Patients received antiplatelet therapy (typically aspirin, dose adjusted to investigator) and antihypertensive and cholesterol-lowering drugs when indicated
  • Surgical technique decided by individual surgeons, but simultaneous vascular procedures were discouraged
  • Neurological follow up at 1, 3, 6, 9, and 12 months, then every 4 months
  • Carotid doppler ultrasound performed at 1 month, annually, and after cerebrovascular events

Outcomes

Comparisons are CEA vs. medical management.

Primary Outcomes

Ipsilateral stroke at 5 years
With 50-69% stenosis
15.7% vs. 22.2% (RR 0.71; 95% CI 0.48-0.93; P=0.045), NNT=15
With <50% stenosis
14.9% vs. 18.7% (P=0.16)

Secondary Outcomes

Death or stroke at 30 days
With 50-69% stenosis
33.2% vs. 43.3% (RR 0.77; P=0.005), NNT 10
With <50% stenosis
36.2% vs. 37% (RR 0.98; P=0.97)

Subgroup Analysis

  • Factors predicting perioperative stroke or death (P<0.05):
    • Contralateral carotid occlusion
    • Left-sided carotid disease
    • Taking aspirin <650mg daily
    • Absence of MI/angina
    • CT or MR imaging evidence of ipsilateral cerebral infarction
    • Diabetes
    • Hypertension
  • Factors predicting durability of CEA benefit (P<0.05):
    • Male sex
    • Recent stroke
    • Recent hemispheric symptoms
    • Taking aspirin ≥650mg daily

Funding

Funded by NINDS, with SmithKline Beechman providing aspirin.

Further Reading