Extracranial Carotid Stenosis: Surgical Therapy

Asymptomatic carotid stenosis

Surgical therapy (CEA: see below) is indicated for asymptomatic carotid stenosis >60%, high embolic risk, and those with a life expectancy >5 years and a periprocedural stroke/death rate of less than 3% have a proven benefit [2017 ESC Guidelines]. According to the current ESC guideline, there has been more restraint compared with the previous 2011 guidelines regarding recommendations for revascularization in patients with asymptomatic carotid stenosis (60-99% stenosis). Endarterectomy or stent implantation (see below) should be considered only in patients in whom an increased risk of stroke can be objectified (IIa recommendation). In the presence of 60-99% asymptomatic carotid stenosis, CEA (see below) should be considered unless there is an increased risk of surgery and one or more clinical or imaging findings associated with an increased risk of carotid-related stroke during follow-up [S3 guideline]. Factors associated with increased risk of stroke in asymptomatic carotid stenosis (modified from [2017 ESC Guidelines]):

Clinical symptoms*	Contralateral transistor ischemic attack (TIA) or apoplexy (stroke)
Cross-sectional imaging of the brain	Ipsilateral (“on the same side”) silent infarction
Sonography (ultrasound)	Stenosis progression/increase in narrowing (>20%).
	Detection of spontaneous emboli (HITS) by transcranial (“through the skull“) Doppler sonography (TCD).
	Impaired cerebral vascular reserve.
	Large plaques (> 40 mm2)
	“Echolucent plaques” (“echo-transparent plaques”).
	Increased juxtaluminal hypoechogenic area.
MR angiography (MRA)	Hemorrhage into the plaque
	Lipid-rich necrosis core

* Age is not a predictor of worse outcome.

Legend

• HITS: high intensity transient signal
• MR angiography: magnetic resonance angiography (MRA).

Symptomatic carotid stenosis

Indications for revascularization (→ endarterectomy) [2017 ESC Guidelines].

• From a degree of stenosis of the internal carotid artery of 50%, if the periprocedural risk of suffering an apoplexy (stroke) or dying as a result of the procedure is less than 6%.
• Revascularization is clearly recommended above a stenosis grade of 70% (recommendation class I, evidence level A).
• If the degree of stenosis is between 50 and 69%, revascularization should be performed (recommendation class IIa, evidence level A)

After a neurologic event in carotid stenosis, carotid endarterectomy (CEA) should be performed as early as possible. In particular, CEA benefits:

• Men
• Patients
  • > 70 years
  • With insufficient stenoses
  • Insufficiency collateral circulation (bypass circulation).

1st order

• Carotid thromboendarterectomy (carotid TEA; carotid endarterectomy, CEA) – in cases of high-grade carotid artery stenosis (narrowing), thromboendarterectomy (TEA; surgical recanalization of the vessel) with dilatation plasty is performed:
  • In patients with a 70-99% stenosis after retinal ischemia (reduced blood flow to the retina/retinal), TIA (transient ischemic attack; sudden circulatory disturbance of the brain leading to neurologic dysfunction that resolves within 24 hours), or nonobstructive stroke, CEA should be performed.
  • CEA should also be performed in patients with symptomatic stenosis of 50-69% when there is no increased risk of surgery.

  [Requires surgery at a center with a complication rate of <3%]

Asymptomatic carotid stenosis: 5-year stroke risk is 5-6% for operated patients and 11% for non-operated patients.Symptomatic carotid stenosis: ECA results in an absolute stroke reduction of approximately 16%. Notes on conservative adjunctive therapy in the setting of CEA:

• Acetylsalicylic acid (ASA).
• Drug and non-drug optimization of vascular risk factors.

2nd order

• Carotid artery stenting (CAS)-insertion of a self-expanding metal prosthesis that holds the narrowed artery open [requires surgery at a center with a complication rate of <6%]; indicated for:
  • CAS may be considered in symptomatic patients with 50-99% carotid stenosis and normal surgical risk [S3 guideline].
  • Increased surgical risk
  • Contralateral paresis of the recurrent laryngeal nerve (paralysis of the laryngeal nerve).
  • Radiogenic stenosis – narrowing of the artery caused by ionizing radiation.
  • Difficult anatomical conditions such as surgically inaccessible sites.
  • Higher grade intracranial or intrathoracic stenosis.
  • Tandem stenosis – two stenoses in succession in one artery.
  • Condition after CEA

Further notes

• A long-term study (10 years) showed that carotid stenting (implantation of a stent in the carotid artery) in patients with symptomatic carotid stenosis protected them as well from subsequent apoplexy (stroke) as classic carotid thromboendarterectomy (CEA), in which the narrowed artery is peeled out, ie. That is, the calcium deposits are surgically removed.However, the stent group showed a 71% increase in risk after five years (cumulative risk for endarterectomy: 9.4% versus 15.2% for carotid stenting).
• The 10-year follow-up of the CREST trial showed no difference between stenting and thromboendarterectomy (TEA) in patients with carotid stenosis. The primary end point of the study was apoplexy (stroke), myocardial infarction (heart attack), and death from any cause. Outcome at 10 years: Event rate stent group 11.8% and in the TEA group 9.9%.
• Another study based on a database from the US government insurer Medicare questions the benefit of carotid stents:
  • 1.7% of patients died while still in the hospital or in the first 30 days postoperatively (after surgery)
  • 3.3% suffered a TIA (transient ischemic attack; temporary circulatory disturbance of the brain) or an apoplexy (stroke) during the above-mentioned period, 2.5% a myocardial infarction (heart attack)
  • At 2 years after stent implantation, 37% of symptomatic and 28% of asymptomatic stenosis patients were dead.

  It is possible that the poor prognosis may explain the high mean age of 76 years and associated comorbidities (concomitant diseases). The two-year mortality rate (death rate) of those over 80 years of age was nearly 42%.

• In 2016, the Joint Federal Committee (GBA) excluded intracranial stents for apoplexy prophylaxis as a health insurance benefit for patients with symptomatic intracranial arterial stenoses. The Institute for Quality and Efficiency in Health Care (IQWiG), commissioned by the GBA, found a significant increase in periprocedural strokes in this patient group.
• Note: Chronic carotid stenosis that develops slowly over many years is less likely to lead to apoplexy than previously thought. According to a study of 3,681 patients with carotid stenosis treated since 1995, 316 patients already had an occluded art. carotid artery when the patients presented to the clinic. Only one patient (0.6%) of these had previously suffered an apoplexy. Three other patients (0.9%) suffered an apoplexy during further observation (until August 2014).
• According to CEA or CAS, mortality (death rate) ranges from 2-5% within the first year. Regarding long-term mortality (long-term mortality rate), no differences are found between CEA and CAS [S3 guideline].