CAROTID STENOSIS

I. Diagnosis

  1. Carotid aa. bruits aren't specific or sensitive for "surgical" stenoses (70-99%); in most severe stenoses bruits are uncommon
  2. Supraclavicular bruit is 96% specific (but not very sensitive) for "surgical" stenoses (both of above from Ann. Int. Med 120:633; n = 1268)
  3. Carotid artery duplex scanning
    1. Uses plain ultrasound plus Doppler to assess peak systolic velocity, on the basis of which is calculated degree of stenosis
    2. Accuracy of Carotid Duplex was 80-89% for mild (< 50%) and severe (> 70%) carotid stenoses but only 46% for moderate (50-69%) stenoses, in one study using angiography as the gold standard (Radiol. 214:247, 2000--JW)
  4. Magnetic Resonance Angiography-Probably more accurate than duplex ultrasound
    1. In a meta-analysis of 63 studies comparing either MRA or duplex u/s to DSA as the gold standard for dx of carotid artery stenosis (Stroke 34:1324, 2003):
      1. For diagnosis of 70-99% stenosis, MRA had sens 95%/spec 90% and u/s had sens 86%/spec 87% (MRA sig. better discriminatory power)
      2. For diagnosis of total occlusion, MRA had sens 98%/spec 100%; u/s had sens 96%/spec 100% (no sig. diff. in discriminatory power)

II. Risks of carotid endarterectomy

  1. 30d risk of death = 1.1%, disabling CVA = 1.8%; nondisabling CVA = 3.7%. Independent predictors of perioperative CVA or death were as follows ("NASCET" trial, Stroke 30:1751, 1999--JW)
    1. Hemispheric (as opposed to retinal) TIA
    2. Left-sided procedure
    3. Contralateral carotid a. occlusion
    4. Ipsilateral ischemic lesion on CT
    5. Ipsilateral ulcerated placque

III. Carotid endarterectomy to treat symptomatic carotid stenosis (positive h/o TIA or CVA)

  1. Carotid endarterectomy ass'd with sig. reduction in risk of ipsilateral CVA c/w medical management alone in pts with h/o TIA or nondisabling CVA and >70% extracranial carotid artery stenosis (Lancet 337:1235, 1991; "NASCET" trial--NEJM 325:445, 1991)
    1. Pts > 75yo more likely to benefit from endarterectomy with less baseline stenosis--In a follow-up trial of a subset of 2,885 NASCET pts > 75yo with symptomatic internal-carotid a. stenosis (Lancet 357:1154, 2001--JW)
      1. Those w/baseline stenosis 70% or more had RR for ipsilateral ischemic CVA of 0.71 among pts > 75yo, 0.85 in pts 65-74, and 0.9 in pts < 65yo
      2. Those w/baseline stenosis 50-69%, only pts > 75yo had sig. lower risk for ipsilateral ischemic CVA (RR 0.83)
      3. Perioperative risk of (CVA or death) was 5% for pts > 65yo
  1. European Carotid Surgery Trial--Multicenter trial of 3,000 pts with carotid stenosis and at least one carotid territory TIA randomized to endarterectomy vs. observation; mean f/u 6y. No sig. diff. in rate of major stroke or death in overall comparison. Among pts with at least 80% stenosis, surgical group had sig. lower 3y risk of major stroke or death (14.9 vs. 26.5%). Among women, sig. benefit from surgery only seen with 90% or more stenosis (Lancet 351:1379, 1998--JW)
  1. 858 pts with h/o TIA or nondisabling CVA and 50-69% carotid a. stenosis randomized to endarterectomy vs. medical management, sig. less risk of ipsilateral CVA over 5y of f/u (15.7% vs. 22%; greater benefit in men); no sig. diff. in 5y risk of ipisilateral CVA in 1,368 pts with < 50% stenosis(NEJM 339:1415, 1998--JW--a f/u of NASCET?)

IV. Carotid endarterectomy to treat asymptomatic carotid stenosis (no h/o TIA or CVA)

  1. "Asymptomatic Carotid Atherosclerosis Study" ("ACAS"; JAMA 273:1421, 1995)
  1. Multicenter trial randomized 1662 pts 40-79yo with >60% stenosis & no sx to ASA or carotid endarterectomy; "selected for low surgical risk"
  2. Median followup 2.7y
  3. 2.3% perioperative incidence of CVA or death in CEA group
  4. Estimated 5y risk for ipsilateral CVA or any perioperative CVA was 5.1% in CEA group vs. 11% in control group
  1. 372 asymptomatic pts with carotid bruits and at least 50% stenosis in at least one carotid artery were randomized to 325mg ASA QD or placebo, followed for mean 2.4y; no difference in cerebral ischemic events, progression to higher grade of stenosis, or death. (Ann. Int. Med. 123:649, 1995)
  2. Meta-analysis of 5 trials (total 2440 pts) with asymptomatic carotid stenosis 50% or more randomized to surgery or no; over 3y f/u, risk of (ipsilateral stroke or perioperative stroke or death) was 4.4% for surgical pts vs. 6.4% for those not randomized to surgery (sig.). 30d post-op risk of stroke or death was 2.4% in the surgery groups (BMJ 317:1477, 1998--JW)

V. Carotid stenting--only 2% restenosis rate at 19mos in one uncontrolled study of 170 pts (JACC 35:1721, 2000--JW)

See Lancet 353:2105, 1999 for a retroactively validated scoring system to predict benefit from carotid endarterectomy in pts with > 70% stenosis