Northeast Florida Medicine
Vol. 66, No. 3 2015
39
Endovascular Neurosurgery
tion. In subsequent years other trials have confirmed the
advantages of CAS and refined the indications for both
CEA and CAS.
15-17
Treatment Recommendations
The distinct separation between symptomatic and
asymptomatic carotid disease is paramount because any
extrapolation on the benefits from revascularization is
dependent on clear-cut definitions of the terms symptom-
atic and asymptomatic. The confusion exists because some
‘symptomatic’ patients experience symptoms that are not
referable to the carotid system. These include syncope,
generalizedweakness, dizziness, and visual changes (scotoma
or floaters). These events do not qualify as symptomatic
carotid stenosis. The typical clinical scenario involves a
transient or permanent focal neurological deficit involving
the ipsilateral retina or cerebral hemisphere in order to
label the carotid stenosis as symptomatic.
The degree of stenosis, the presence or absence of
symptoms referable to the carotid stenosis, the estimated
surgical risk, and patient age (especially over 80 years) are
the main factors when deciding to intervene on a patient
with ICA stenosis.
Symptomatic and Asymptomatic Patients
The use of CAS in the United States is primarily de-
termined directly and indirectly by the Food and Drug
Administration (FDA) and Centers for Medicare and
Medicaid Services Policy (CMS). The initial position of the
FDA had been to support clinical application of CAS for
carotid revascularization only in patients considered high
risk for CEA (Table 1). In addition, patients eligible for CAS
either had a recent stroke with at least a moderate carotid
stenosis (50 percent or greater) or did not have a recent
stroke but were found with severe stenosis (80 percent or
greater). Following overwhelming evidence from clinical
trials, especially data from the CREST Trial (Carotid Re-
vascularization Endarterectomy versus Stenting), the FDA
expanded the recommendations for CAS and included
patients with average-to-low risk for CEA.
16,18
Today, evi-
dence-based guidelines have been proposed to determine
the use of CAS and these treatment recommendations were
assessed according to criteria published by the American
Heart Association/American Stroke Association (AHA/
ASA) and the University of Oxford’s Center for Evidence
Based Medicine (CEBM).
19
The guidelines are as follows:
• CAS should be considered in symptomatic patients
with severe stenosis (70 percent) who have a high-
risk for CEA. (AHA/ASA Class IIb; Level of Evi-
dence B, CEBM Level 2b, Grade B19)
• CEA is recommended in symptomatic patients with
moderate-to-severe stenosis (50-69 percent). CAS
is considered an alternative to CEA for patients at
average-to-low risk of endovascular treatment and pa-
tients who are considered high risk (over 6 percent of
morbidity and mortality) for CEA. (AHA/ASA Class
I; Level of Evidence B, CEBM Level 1b; Grade B)
• The benefit of CAS in asymptomatic patients is less
clear and there is uncertainty regarding CAS over
CEA. (AHA/ASA Class IIb; Level of Evidence B,
CEBM Level 2b, Grade B20)
• In patients with carotid stenosis less than 50 percent
there is no indication for CEA or CAS. (AHA/ASA
Class III; Level of Evidence B, CEBM Level 1b;
Grade B19)
In addition, data from CEA and CAS trials provided
the basis to determine an upper limit for complications
following carotid revascularization.These recommendations
established an upper limit of 6 percent for perioperative
risk of stroke and death in symptomatic patients and 3
percent upper limit in asymptomatic patients, assuming
a life expectancy exceeding five years.
21,22
Competency
regarding the management of carotid stenosis is usually
based on the benchmark of a complication rate inferior
to the recommended thresholds, or else the morbidity and
mortality from treatment outweighs the natural history
of carotid stenosis. Overall, patient selection is the most
important factor tominimize complications associated with
CAS. Commonly recognized risk factors include medical,
neurologic, anatomic, and genetic arteriopathy (Table 2).
Advanced age is often considered a risk factor. In the SAP-
PHIRE trial,
13
patients 80 years or older were considered
high risk for CEA. However, the CREST trial 17 showed
that CAS is beneficial in patients younger than 70 years
old. We suggest that age alone should not be considered in
determining CEA versus CAS and other, patient-specific,
factors should be considered.
The major medical risk factor for patients with carotid
stenosis is myocardial infarction (MI). A patient with carotid
stenosis may also have severe coronary disease.
A sudden decline in blood pressure and onset of severe
bradycardia may occur during intervention, after manipula-
tion of the carotid sinus. The result is MI. Neurologic risk
factors for CAS include recent large infarction, crescendo
TIA’s, and stroke in evolution. A large hemispheric infarc-
tion may be complicated by an intracerebral hemorrhage.
Treatment of these patients is usually delayed 4-6 weeks
to allow the stroke tissue to ‘heal’ before intervention. Pa-
tients with acuteTIA’s or stroke in evolution require urgent
treatment but there is increased risk of stroke or death.
