Currently, carotid angioplasty and stenting is useful in patients who are not good candidates for carotid endarterectomy because of anatomically inaccessible lesions, restenosis following previous endarterectomy, radiation-induced stenosis, and other high-risk conditions.
Dr. Cloft is an Assistant Professor of Radiology at Emory
University Hospital, Atlanta, GA.
Currently, carotid angioplasty and stenting is useful in
patients who are not good candidates for carotid endarterectomy
because of anatomically inaccessible lesions, restenosis following
previous endarterectomy, radiation-induced stenosis, and other
high-risk conditions. The practice of carotid endarterectomy is
supported by large prospective, randomized, controlled trials that
demonstrate that it is an effective therapy for symptomatic carotid
stenosis if the complication rate of the procedure is <6%, and
that it is effective for asymptomatic stenosis if the complication
rate is <3%. Because carotid endarterectomy is a relatively
simple and low-risk surgical procedure, it will be difficult to
prove that carotid artery angioplasty and stenting is as safe and
effective as carotid endarterectomy. Recently published series of
carotid angioplasty and stenting report stroke and death rates
ranging from 2% to 8%.
Justification for invasive treatment of carotid
It will not be easy for carotid angioplasty and stenting to
supplant carotid endarterectomy. Carotid endarterectomy is a
relatively simple surgical procedure and the artery is generally
easily accessible. The complication rate is very low with
experienced surgeons, and the procedure can be done under local
anesthesia. The practice of carotid endarterectomy is supported by
multiple prospective randomized controlled trials. In these
multicenter trials, bias was minimized and end points were well
defined. The results of these trials are published in the most
important medical journals.
The North American Symptomatic Carotid Endarterectomy Trial
(NASCET) study initially demonstrated a benefit with surgery for
symptomatic patients with stenosis >70% and a 5.8% risk of
perioperative stroke and death.
A moderate reduction of stroke risk was later shown by NASCET for
endarterectomy in patients with stenosis of 50% to 69%.
The European Carotid Surgery Trial (ECST) demonstrated a benefit
with surgery for symptomatic patients with a stenosis >70% and
if the complication rate is <7%.
The Asymptomatic Carotid Atherosclerosis Study (ACAS) trial
reported a benefit for asymptomatic patients with >60% stenosis
and a complication rate <3%.
Literature regarding carotid angioplasty and
The data supporting the use of angioplasty and stenting of
carotid artery stenosis is not nearly so compelling as that
supporting carotid endarterectomy. No trials comparing carotid
angioplasty and stenting with carotid endarterectomy have been
published. A number of large case series of carotid angioplasty and
stenting have been published. Theron et al
of France reported 69 cases complicated by 2 embolic events (3%)
and no deaths. Diethrich et al
of the Arizona Heart Institute reported 110 cases with a 6.4%
periprocedural stroke rate and a 2% periprocedural death rate. The
University of Alabama group reported the results of 271 cases, with
a 7% rate of neurological events (4% permanent) and 1 death
has reported experience with carotid angioplasty and stenting in
315 cases with a 3.8% rate of perioperative stroke and death. Henry
subsequently reported the results of 315 carotid angioplasty and
stent procedures with a 3.9% risk of stroke, including 1 death. The
Washington Hospital Center reported their experience with 140
cases, which were complicated by a 6.4% periprocedural stroke rate
and 1 death.
There are problems with the published data regarding carotid
angioplasty and stenting. The data comes from uncontrolled trials
with variable patient selection; the data is often collected
retrospectively; the collection of data is not blinded or otherwise
unbiased; end-points are not well defined; and follow-up is
incomplete. The data is published in subspecialty journals, obscure
journals, or nonpeer-reviewed journals.
Wholey et al
have reported the results of a survey of institutions throughout
the world performing carotid artery angioplasty and stenting. A
total of 5210 procedures were performed at 36 medical centers.
These medical centers reported a technical success rate of 98.4%.
The combined periprocedural stroke and death rate was reported to
be 5.1%. The quality of data collection at each of these
institutions is difficult to ascertain. Also, this type of survey
information is subject to the bias of those reporting the
information. This bias will almost certainly lead to an
underreporting of complications. Therefore, this type of survey
data cannot be viewed as a substitute for rigorous clinical
What is really important is how carotid angioplasty and stenting
compare with surgery and with the natural history of symptomatic
and asymptomatic carotid stenosis. This can be best determined by
simply measuring and comparing the proportions of patients who
reach specific clinical end points (especially stroke and death).
The data from the published case series of carotid angioplasty and
stenting is generally presented in a favorable light because only a
small fraction of the patients treated have a complicating
neurological event. This data appears less favorable, however, when
one considers that 88% of symptomatic patients and at least 95% of
asymptomatic patients would not have a stroke during the first year
of medical therapy (i.e., if they had not undergone surgery or
carotid angioplasty and stenting).
Most patients treated with carotid angioplasty and stenting have
symptomatic atherosclerotic carotid stenosis (figure 1). For
asymptomatic patients, the complication rate for the procedure must
be below 3% and the patient must have a survival expectancy of at
least 5 years to realize any benefit from correction of their
carotid stenosis by surgery.
Patients thought to be too ill for carotid endarterectomy
may be poor candidates, since this patient population may not
survive long enough to accrue any benefit from the procedure.
However, patients who are poor candidates for surgery because of
previous neck surgery or previous radiation therapy to the neck are
potential candidates for carotid angioplasty and stenting.
Contralateral carotid occlusion has been proposed as an indication
for angioplasty and stenting.
Dissection, with or without pseudoaneurysm, may also occasionally
be treated effectively with angioplasty and stenting (figures 2 and
Carotid angioplasty and stenting is generally performed from a
transfemoral approach. The vessel is selectively catheterized with
a diagnostic catheter, and a diagnostic angiogram is performed.
Patients are generally anticoagulated with 5000 to 10000 units of
heparin to achieve an activated clotting time >300 seconds. They
should also be treated with an antiplatelet agent, such as
clopidogrel, during and after the procedure.
No angioplasty balloon or stent has been approved for use in the
carotid artery by the U.S. Food and Drug Administration (FDA).
Stents that have been used in the carotid have included Palmaz
(Cordis Endovascular, Miami Lakes, FL), Strecker, Wallstents
(Boston Scientific Corp., Natick, MA), and Smart Stents (Cordis
Most of these stents require a 7F lumen for their introduction, but
some Wallstents can now be introduced through a 6F lumen. Lower
profile delivery systems are under development.
Self-expanding stents are now used primarily because they are
not permanently deformed when exposed to compressive forces. Palmaz
stents and other balloon-expandable stents are also sometimes
useful because they can be more precisely positioned than
Wallstents. They have increased "hoop strength" relative to
self-expanding stents, but once they are deformed, they remain
They should be used only if they will not be exposed to crushing
forces, such as when they are positioned high in the carotid artery
behind the mandible.
When putting the guiding catheter into the common carotid
artery, it is usually preferable to place the tip of the exchange
wire in the external carotid artery with a diagnostic catheter, and
then exchange it for the guiding catheter. Before stent placement,
it is usually necessary to predilate the stenosis with a 3.5- to
4.0-mm diameter balloon. The shortest appropriate balloon is used
to optimize inflate/deflate characteristics and to minimize trauma
to the artery adjacent to the stenosis. The stent is deployed
following predilatation. Residual stenosis is dilated with another
angioplasty balloon as appropriate.
Prevention of stroke is the primary goal of carotid angioplasty
and stenting. Stroke is also the most worrisome complication of the
procedure. Carotid angioplasty and stenting theoretically cannot be
performed with less risk than cerebral angiography. The risk of
stroke from cerebral angiography in the ACAS trial was 1.5%.
The risk of permanent stroke from cerebral angiography in patients
with a transient ischemic attack or stroke as an indication for
angiography in 3 prospective studies (1148 patients) was 0.7%.
Therefore, it is doubtful that the risk of stroke during carotid
angioplasty and stenting could ever be less than approximately 1%,
perhaps even with distal protection devices.
The risk of stroke complicating carotid angioplasty and stenting
may be reduced by capturing and removing emboli during the
procedure, which has become known as distal protection. Theron
was the first to promote use of a distal protection device to
reduce the risk of thromboembolic complications during carotid
angioplasty and stenting. Ohki et al
performed angioplasty and stenting on carotid endarterectomy
explants and found that the procedure generally produced numerous
small plaque emboli. This ex vivo experiment has generated much
interest in the issue of distal protection, and a number of devices
are now under development.
It has not yet been proven that any of these devices will reduce
neurological complications of carotid angioplasty and stenting. At
the present time, these devices are experimental and are not used
by most operators. Abciximab may be a means of reducing
thromboembolic complications of carotid angioplasty and stenting,
and, as in coronary angioplasty and stenting, other such
pharmacological adjuncts are likely to be useful.
Carotid stenting is sometimes complicated by bradycardia and
hypotension during or after the procedure.
Bradycardia and hypotension result from stimulation of the carotid
baroreceptor by the expanding balloon or stent. Hypotension
(systolic pressure <90 mm Hg) has been reported to occur in 17%
to 22% of cases.
Vasopressors were required to treat hypotension in 8% to 16% of
cases in some series.
Postprocedural hypotension has been reported to last as long as 4
Postprocedural hypotension seems to occur more commonly with
balloon expandable-stents (26%) than with self-expanding stents
Postprocedural hypotension seems to occur less frequently in
patients with previous ipsilateral carotid endarterectomy,
which may be due to surgical disruption of the carotid baroreceptor
system. Because of the potential for hemodynamic instability, all
patients undergoing carotid angioplasty and stenting should be well
Mendelsohn et al
reported new onset bradycardia in 6 of 19 procedures (32%). In 5 of
these 6 patients, the nadir heart rate occurred within 4 minutes of
balloon dilatation or stent delivery. One patient required
temporary pacing for 21 hours beyond the conclusion of the
procedure. Bradycardia has been reported to occur in 28% of cases
by Qureshi et al,
with 1 of 14 patients with bradycardia requiring transvenous
pacing. Yadav et al
reported bradycardia persisting for a few minutes after balloon
inflation in 71% of 107 patients. Some interventionalists have
recommend routine prophylaxis with atropine.
At some institutions, a temporary pacemaker is inserted routinely.
Others have advocated obtaining femoral venous access in all
patients and making sure that a transvenous pacemaker is available
The rather large femoral sheath required for angioplasty and
stent placement can result in significant complications, such as
fatal retroperitoneal hemorrhage, which accounted for the single
death in the series reported by Yadav et al.
Smaller stent delivery systems are under development, which should
result in fewer arterial access site complications. Closure devices
may reduce serious access site complications, but such a reduction
remains to be proven.
These devices also might add significant financial cost to the
The primary issues that determine if carotid angioplasty and
stenting should be widely applied are safety, efficacy, and
durability. Angioplasty and stenting are getting safer with time,
but carotid endarterectomy also seems to be safer than it was
during NASCET for many surgeons. Therefore, it is important to
directly compare state-of-the-art carotid endarterectomy with
state-of-the-art carotid angioplasty and stenting in order to
assess the relative merits of each procedure realistically and
relevantly. This type of comparison can be made only with a
prospective, randomized, controlled trial.
Some trials have suggested that carotid angioplasty and stenting
are not yet as safe as carotid endarterectomy. The Schneider
Wallstent trial of carotid angioplasty and stenting was stopped
prematurely because of safety considerations regarding the
angioplasty and stenting procedure.
Naylor et al
reported the results of a single-center trial in England in which 5
of 7 patients treated with angioplasty and stenting suffered a
stroke. We are left to wonder whether these trials were not
successful because of problems specific to the devices tested,
because of problems with carotid artery angioplasty and stenting in
general, or because of relative operator inexperience.
A multicenter, prospective, randomized, controlled trial
comparing carotid endarterectomy with carotid artery stenting
(Carotid Revascularization Endarterectomy and Stent Trial [CREST])
has been funded by the National Institute for Neurological Disease
and Stroke and is scheduled to begin enrollment soon. This trial
will allow a much more objective comparison of surgery and stenting
than has been previously possible. A limited number of experienced
operators will participate in the trial. The CREST trial will
utilize the Acculink stent (Guidant Corporation, Indianapolis,
At least two industry-sponsored trials are planned for the near
future. The ARCHeR (Acculink for Revascularization of Carotids in
High-Risk Patients) trial has been designed and funded by Guidant
Corporation to evaluate the Acculink stent in symptomatic and
asymptomatic patients who are at high risk for carotid
endarterectomy. The SAPPHIRE (Stenting and Angioplasty with
Protection in Patients at High-Risk for Endarterectomy) trial has
been designed and funded by Cordis Endovascular. In this trial,
symptomatic and asymptomatic patients will be randomized for
treatment with either carotid angioplasty and stenting performed
with a distal protection device or carotid endarterectomy.
The most compelling argument to perform carotid angioplasty and
stenting would be that it is safer than carotid endarterectomy. No
reliable data to support this argument exists. It is hoped that
trials will provide some reliable data to address this question.
Currently, carotid angioplasty and stenting is useful in patients
who are poor candidates for carotid endarterectomy because of
anatomically inaccessible lesions, restenosis following previous
endarterectomy, radiation-induced stenosis, and other high-risk
Another argument made to support the use of carotid angioplasty
and stenting is that it seems less invasive than surgery. While one
could intelligently argue that endarterectomy performed under local
anesthesia is not really any more invasive, such an argument may be
irrelevant because many patients will probably perceive
endarterectomy to be more invasive and choose to have angioplasty
and stenting. An increasing number of patients will know carotid
angioplasty and stenting exists as an option because it is being
publicized on the Internet and in other media. Since patients are
taking an more active role in medical decision making, the
perception of carotid angioplasty and stenting as less invasive by
patients could be very important.
There are also cultural forces that are influencing the medical
decision-making process. There is a widespread sense that "everyone
else is doing it," and physicians do not want to miss the
development of new technology for fear of being left behind.
Doctors and patients like new devices, so there is a tendency to
embrace treatments that involve new technology. As this new
technology develops, there may be devices to sell, so the medical
device industry is highly motivated to develop the technology and
encourage its use. The stent industry, which has been highly
successful in selling coronary stents, has become quite competitive
and is looking for new markets. In 1996, 130,000 carotid
endarterectomies were performed in the United States,
and it is possible that a similar number of carotid angioplasty and
stent procedures might be performed in the near future.