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Comparison between NASCET and ECST methods in the study of carotid artery stenosis

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

In the 1990s the North American Symptomatic Carotid Endarterectomy Trial (NASCET) (1) and European Carotid Surgery Trial (ECST) (2) proved the benefits of performing endarterectomy in those patients with symptomatic high-grade stenosis (70-99%).

In 1995, the Asymptomatic CarotidAtherosclerosis Study (ACAS) (3) also, suggested surgery for high-grade asymptomatic stenosis

The North American Symptomatic Carotid Endarterectomy Trial (NASCET) demonstrated a conclusive benefit for carotid endarterectomy in patients with symptomatic 70-99% ICA stenosis (1)

NASCET was established by angiographic calculation of ICA stenosis percentage using the following formula:

  • % ICA stenosis = (1 - [narrowest ICA diameter/diameter normal distal cervical ICA]) x 100

The European Carotid Surgery Trial (ECST) also demonstrated benefits for carotid endarterectomy in patients with symptomatic higher than 80% ICA stenosis (2).

ECST was established by angiographic calculation of ICA stenosis percentage using the following formula:

  • % ICA stenosis = (1 - [diameter of the most stenotic part/estimated original diameter at the site of the stenosis]) x 100

Notes:

  • conventional angiography has been considered the standard method for evaluating carotid stenosis and the trials published in the 1990s (NASCET, ECST, and ACAS) were based on this method
    • however, the introduction and development of ultrasound doppler, CT angiography (CTA) and MRI angiography (MRA) have been replacing angiography for diagnostic purposes
      • this has essentially reserved angiography only for endovascular treatment
    • doppler ultrasound has become the first choice for carotid stenosis screening, permitting the evaluation of both the macroscopic appearance of plaques as well as flow characteristics (4)
      • if there is haemodynamically significant carotid stenosis is usually referred to a further CTA or MRA study

Reference:

  • Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N. Engl. J. Med. 1991;325 (7): 445-53.
  • Randomised trial of endarterectomy for recently symptomatic carotid stenosis: final results of the MRC European Carotid Surgery Trial (ECST). Lancet. 1998;351 (9113): 1379-87.
  • Endarterectomy for asymptomatic carotid artery stenosis. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. JAMA. 1995;273 (18): 1421-8.
  • Grant EG, Benson CB, Moneta GL et-al. Carotid artery stenosis: gray-scale and Doppler US diagnosis-Society of Radiologists in Ultrasound Consensus Conference. Radiology. 2003;229 (2): 340-6

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