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Treatment Strategies for Patients with Acute Carotid Syndromes
is now a well-recognized indicator for atherosclerotic disease Figure 1: Atherosclerotic Plaque with Thrombus Formation
development in carotid arteries.
7
Conventional arteriography was
Linked to a High Risk for Distal Embolization in Cases of
considered the gold standard for diagnosis of acute carotid
Carotid Angioplasty
syndromes, but it under-represents the atherosclerotic burden of the
aortic arch and exposes the patient to a measurable risk for stroke.
Contrast-enhanced computed tomography (CT) axial images are
obtained to include the ascending and descending aortic arch. The 3D
CT angiographic analysis of the aortic arch, common carotid artery
(CCA), and internal carotid artery (ICA) is a non-invasive diagnostic
tool for treatment planning. Useful information can be gleaned from
axial CTA images, but tortuosity and lengths are much better
evaluated with some type of 3D rendering. Magnetic resonance
imaging (MRI) does not easily depict calcium, whereas CT scans do.
Table 1: Anatomical Criteria for Hazardous
Carotid Artery Stenting
Currently, there is no commercially available MR program that
characterises carotid plaque components.
Anatomical Criteria Problems for Carotid Artery Stenting
Treatment Strategies
Vessel Access Problems
‘Difficult’ arch Type III arch configuration, severe
Timing of Revascularization
arch atherosclerosis
The optimal timing of elective CEA in ACS, particularly after a recent
Tandem CCA stenosis Potential for failed/unsafe access or
minor stroke, remains controversial. Early surgery (within 30 days after distal embolization
stroke) of a stenotic but patent ICA has been associated with the fear
Lesion Characteristics
that ICA revascularization might convert non-hemorrhagic infarction Near-occlusions Lesion too stenotic to be crossed
into a hemorrhagic one, or at least cause an enlargement of the
EPD without unprotected pre-dilatation
infarction zone.
8–10
Therefore, the strategy to delay surgery after a
Circumferential lesion Higher risk for athero-embolism or
recent stroke for four to six weeks has been accepted in clinical
calcification suboptimal result (residual stenosis)
practice for many years. Ballotta et al.
11
showed that early CEA (<30
Distal ICA/Intracranial
days) after a minor stroke can be performed safely with a total peri-
True carotid ‘string sign’ High risk for occlusion due to low flow;
operative mortality and morbidity of 2%, which was similar to that
distal ICA too small for EPD
Distal ICA tortuosity Unable to safely deploy EPD
seen in the control group undergoing delayed CEA. Piotroski et al.
12
Severe intracranial disease Potential for embolization from
found no significant difference in the incidence of cardiovascular
wire manipulation
events and deaths between patients operated on sooner or later than
CCA = common carotid artery; EPD = embolic protection device; ICA = internal carotid artery.
six weeks after their stroke.
invasive procedure, potentially minimizing the risks of wound
Potential reasons for delays to CEA include patient factors (delayed complication and cranial nerve injury. In addition, this may translate
symptom recognition and presentation to medical attention), physician to shorter lengths of hospitalization and less resource utilization.
16
factors (delayed diagnosis and referrals), and resource availability CAS can also be considered as a first-line treatment in cases of
(rapid access to vascular imaging).
11
A time-dependent benefit was tandem stenosis, hostile necks after radiation, or clopidogrel
particularly evident in patients with moderate (50–69%) symptomatic administration due to drug-eluting stent placement linked to potential
carotid stenosis. In this patient sub-population, CEA was beneficial if operative bleeding.
performed within the first two weeks, but the benefit was lost when
surgery was delayed for more than three months.
11
A number of randomized controlled trials designed to test the
non-inferiority of CAS versus CEA have been conducted.
17–20
However,
Large randomized clinical trials from the early 1990s have shown the due to a number of methodological and statistical problems, drawing
superiority of CEA and aspirin therapy in preventing stroke compared any definitive conclusions is still problematic and the use of CAS
with aspirin therapy alone for the treatment of symptomatic COD.
13–15
remains controversial. Criteria used to evaluate each patient’s
On the basis of these trials, the most recent American Heart suitability for CAS were largely subjective and not prospectively
Association (AHA) guidelines recommended CEA for symptomatic standardized. Consideration was given to the degree of
patients with a stenosis of 50–99% if the peri-operative risk for stroke atherosclerosis and tortuosity present in the aortic arch, ipsilateral
or death is <6%.
13–15
CCA, and ICA that would complicate the placement of a sheath, stent,
or distal EPD. Examples of such hostile anatomy would include
Surgery and Carotid Stenting significant CCA stenosis, short CCA with external carotid artery (ECA)
Due to recent advances in endovascular techniques, CAS can now be occlusion, or 180° bends in the CCA or ICA. Unfavorable anatomies
considered as an alternative treatment for COD. Moreover, as include elongated or type III aortic arch configurations,
institutions and operators have gained more experience with CAS, the circumferential calcification of the bifurcation lesion, or long lesions
likelihood of treating more challenging anatomy and potentially sicker requiring more than one stent (see Table 1). On the other hand,
patients is expected. CAS has the added benefit of being a less favorable morphology is type I aortic arch configuration.
US CARDIOLOGY 85