Carotid Stenosis

Aka: Carotid Stenosis, Carotid Artery Stenosis

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II. Technique

  1. See Arterial Bruit

III. Epidemiology

  1. CVAs caused by atherosclerosis of Internal Carotid Artery or intracranial arteries: 15%

IV. Symptoms

  1. Contralateral weakness or numbness
  2. Ipsilateral blindness or Amaurosis Fugax
  3. Dominant hemisphere involvement
    1. Dysphasia or Aphasia
    2. Apraxia

V. Exam

  1. See Neurologic Exam
  2. Carotid Bruit
    1. Unreliable due to low Test Sensitivity and Specificity

VI. Evaluation

  1. Universal Screening in asymptomatic patients does not improve outcomes
    1. High False Positive Rate in general population
    2. LeFevre (2014) An Intern Med 161(5): 356-62 [PubMed]
  2. Symptomatic patients with possible CVA, TIA or Amaurosis Fugax should be evaluated for Carotid Stenosis

VII. Imaging: Preferred First-Line Studies

  1. Carotid Artery Duplex Ultrasonography
    1. Degree of stenosis is estimated from Blood Flow velocities along the carotid course
      1. Flow rates increase as stenosis increases
      2. Measurements altered in tortuous or highly calcified arteries
    2. Standard first-line diagnostic tool for Carotid Stenosis
      1. However, do not make clinical decisions based on Ultrasound alone (due to False Positives)
      2. Confirm findings with either a MRA or CTA
    3. Less expensive than MRA
    4. Accuracy for diagnosing severe Carotid Stenosis
      1. Test Sensitivity: 86%
      2. Test Specificity: 87%
  2. CT Angiography with 3D reconstruction
    1. Requires intravenous iodinated contrast exposure and radiation exposure
    2. Approaches 100% Test Sensitivity and Specificity when screening for mild Carotid Stenosis
    3. However, poorly differentiates between moderate and severe Carotid Stenosis
      1. Test Sensitivity: 60 to 65%
      2. Test Specificity: 88 to 93%
      3. Anderson (2000) Stroke 31:2168-74 [PubMed]
  3. Carotid Magnetic Resonance Angiography (MRA)
    1. Better than Ultrasound at defining carotid anatomy
    2. Accuracy for diagnosing severe Carotid Stenosis
      1. Test Sensitivity: 95%
      2. Test Specificity: 90%
  4. References
    1. Nederkoorn (2003) Stroke 34:1324-32 [PubMed]

VIII. Imaging: Other studies

  1. Angiography
    1. Gold standard which allows evaluation of the entire carotid system
    2. Invasive procedure with risk of neurologic complications
    3. Now used primarily to resolve imaging discrepancies in perioperative period

IX. Management: Symptomatic Carotid Stenosis

  1. Indications for carotid endarterectomy
    1. Transient Ischemic Attack or CVA within prior 6 months AND
    2. Ipsilateral severe Carotid Artery Stenosis (>70%, consider for >50% by angiography) AND
    3. Estimated perioperative morbidity and mortality <6%
      1. https://riskcalculator.facs.org/RiskCalculator/
      2. Surgical risk increases with neck region related factors
        1. Tracheostomy or other neck surgery
        2. Prior neck radiation
        3. Restenosis of prior carotid endarterectomy
  2. Endarterectomy carries risk of significant morbidity
    1. Cognitive changes may be difficult to discern
    2. Risk of CVA within 30 days of procedure: 7%
  3. Symptomatic patient with Carotid Stenosis >70%
    1. Intervention offers greatest benefit (17% Absolute Risk Reduction at 2 years per NASCET study)
    2. Significant benefit from carotid endarterectomy
    3. Benefits include patients over age 75 years
    4. CVA will occur in 1-2% of patients with >70% stenosis who do not undergo intervention
  4. Symptomatic patient with Carotid Stenosis 50 to 69%
    1. Benefit from carotid endarterectomy
    2. Benefits include patients over age 75 years
  5. Symptomatic patient with Carotid Stenosis <50%
    1. No benefit from carotid endarterectomy
    2. See Prevention of Ischemic Stroke

X. Management: Asymptomatic Carotid Stenosis >60%

  1. Consider carotid endarterectomy for asymptomatic Carotid Stenosis >80%
  2. Medical therapy: Indicated if Carotid Stenosis <80%
    1. Overall CVA Risk on medical therapy: 12% CVA 5 year risk
    2. See Prevention of Ischemic Stroke
    3. Hypertension control (typical goal is <130/80)
      1. Exercise caution with bilateral Carotid Stenosis
    4. Hyperlipidemia control with Statins
    5. Antiplatelet options
      1. Aspirin
      2. Other antiplatelet agents are not recommended
        1. Clopidogrel (Plavix)
          1. Do not use concurrently with Aspirin
        2. Aspirin with Dipyridamole (Aggrenox)

XI. Management: Surgical Procedures

  1. Overall CVA Risk on surgical therapy: 6% CVA 5 year risk
  2. Relative contraindications to carotid endarterectomy
    1. Women show less benefit in asymptomatic Carotid Stenosis
    2. Life Expectancy <5 years
    3. Active cardiovascular disease
    4. Age over 80 years
    5. Concomitant intranial stenosis
    6. Contralateral Carotid Stenosis
  3. Carotid endarterectomy
    1. Five year stroke risk reduction decreases with endarterectomy delay from symptom onset (>50% Carotid Stenosis)
      1. NNT 5 if endarterectomy performed within 2 weeks of symptom onset
      2. NNT 125 if endarterectomy performed within 12 weeks of symptom onset
    2. Complications
      1. Stroke or death occurs within 7% of patients in first 30 days, and 15% within 5 years
      2. Rerkasem (2020) Cochrane Database Syst Rev (9): CD001081 [PubMed]
  4. Angioplasty with Stent and Distal Protection
    1. As effective as carotid endarterectomy
    2. May be preferred in patients at high risk of complications due to comorbidity
      1. (2006) Lancet 368:1239-47 [PubMed]
      2. Park (2006) Am J Surg 192: 583-8 [PubMed]
    3. Higher risk of morbidity and mortality in first 3 months after intervention (NNH 32 compared with endarterectomy)
      1. Increased risk appears due to stenting of an unstable Plaque (esp. age >70 years)
      2. Those age <70 years have similar complication rates to carotid endarterectomy at 3 months
      3. After 3 months, complication rates are the same
      4. European trials (SPACE and EVA-3S) studies with high complication rates did not use distal protection devices
      5. Muller (2020) Cochrane Database Syst Rev (2): CD000515 [PubMed]
      6. Rantner (2013) J Vasc Surg 57(3): 619-26 [PubMed]
      7. Bonati (2011) Eur J Vasc Endovasc Surg 41(2): 153-8 [PubMed]
  5. Transcarotid Artery Revascularization
    1. Newer carotid revascularization procedure
    2. Carotid Artery clamped proximal top stenosis, artery incised and clot removed
    3. Trialed in patients at high risk of endarterectomy complications with stroke or death 2.3% at 30 days
      1. Kashyap (2020) Stroke 51(9): 2620-9 [PubMed]

XII. References

  1. Alamowitch (2001) Lancet 357:1154-60 [PubMed]
  2. Ellis (1992) Eur J Vasc Surg 6(2):172-7 [PubMed]
  3. Firnhaber (2022) Am Fam Physician 105(1): 65-72 [PubMed]
  4. Gutierrez (1985) Am Surg 51(7):388-91 [PubMed]
  5. Halliday (2004) Lancet 363:1491-502 [PubMed]
  6. Rothwell (2003) Lancet 361:107-16 [PubMed]
  7. Shorr (1998) J Gen Intern Med 13(2):86-90 [PubMed]

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