Carotid Angioplasty for the Management of Carotid Occlusive
Disease
By Michael S. Dahn, M.D.
Cerebrovascular disease is the third leading cause of death
in the United States.1 It is associated with 700,000 strokes per
year resulting in huge morbidity and a significant economic
burden to our society. Approximately 20 to 35 percent of these
strokes are attributable to extracranial carotid occlusive
disease.2 Consequently, clinical management of carotid stenosis
has been intensively studied for decades.
Currently, carotid endarterectomy (CEA) is the primary
modality used to treat asymptomatic and symptomatic carotid
stenosis. The efficacy of CEA in the management of carotid
stenosis has been proven and its durability reaffirmed through
prospective trials including the North American Symptomatic
Carotid Endarterectomy Trial (NASCET),3 Asymptomatic Carotid
Artery Stenosis Trial (ACAS),4 European Carotid Stenosis Trial
(ECST)5 and Asymptomatic Carotid Stenosis Trial (ACST)6 trials.
For example, the NASCET trial has demonstrated that the two-year
ipsilateral stroke risk for symptomatic occlusive disease in the
70 to 99 percent range is 9 percent for patients undergoing
carotid endarterectomy and 26 percent for patients undergoing
the best medical therapy. Furthermore, peri-procedural adverse
events such as stroke, myocardial infarction and death
associated with each respective approach were similar (5.8
percent for endarterectomy and 3.3 percent for best medical
management).
In contrast, observed morbidity and mortality rates for the
application of carotid angioplasty to seriously ill patients had
been reported to be in the range of 12 to 33 percent7,8.
Counsell, et al9 reported the early termination of a randomized
trial comparing carotid endarterectomy with angioplasty because
five of the first seven patients entered into the angioplasty
arm suffered a stroke suggesting that this procedure was
associated with excessive risk. Finally, Golledge, et al10
reported that the risk of stroke and death associated with
carotid angioplasty was almost twice (7.8 percent) that compared
with carotid endarterectomy (4.0 percent). In view of these
findings, one might question the value of pursuing this
alternative technique for the management of carotid occlusive
disease.
Carotid endarterectomy remains an effective treatment for
carotid stenosis as established by evidenced based medicine
whereas carotid angioplasty appears to exhibit considerable
risk. However, despite the risks associated with carotid
angioplasty, persistent and tenacious investigators have
continued to improve angioplasty and carotid artery stenting (CAS).
This has resulted in a variety of refinements to the
procedurewhich make it a realistic alternative to surgical
management of carotid artery stenosis.
Although early studies of carotid angioplasty have been
associated with a higher stroke risk following angioplasty when
compared to carotid endarterectomy, recent clinical trials have
suggested the equivalency of carotid angioplasty with carotid
endarterectomy as a consequence of refinements incarotid
angioplasty technique.11,12
The SAPPHIRE trial has received the greatest attention in
this regard.11 This was an industry sponsored (Cordis, Inc.)
prospective trial evaluating high-risk patients exhibiting
carotid stenosis randomized to either carotid angioplasty with
stent placement (CAS) or carotid endarterectomy. The outcome of
this trial revealed a statistical benefit in the major adverse
event rate (combined death, stroke and myocardial infarction
rate) in favor of CAS (5.8 percent) when compared to carotid
endarterectomy (12.6 percent) at 30 days. A number of additional
CAS single arm trials have reported comparable major adverse
event rates to the SAPPHIRE stenting arm. Although these
additional trials show results consistent with SAPPHIRE, these
studies rely upon historical surgical data with no concurrent
comparators The CARESS trial, which was funded by the
International Society of Endovascular Specialists, was a
randomized trial, which does contain carotid endarterectomy as a
comparator arm.13 This study demonstrated that there was no
significant difference in the 30-day combined all-cause
mortality and stroke rate between CEA (2 percent) and CAS (2
percent). This report concluded that the 30-day risk of stroke
or death following CAS with cerebral protection is equivalent to
CEA. A recent update of this trial has indicated that there was
no significant difference in the one-year combined all-cause
mortality and stroke rate between CEA (13.6 percent) and CAS
(10.0 percent). Significantly the CARESS trial included a
patient population that was not limited to high risk patients.
Inclusion of all patients as candidates for carotid artery
angioplasty and stenting, not just high risk subjects, is the
trend in this field..
The current CAS experience here at UConn is consistent with
recent reports indicating the CAS can be accomplished with a low
rate of adverse events. Our clinical experience observed a major
event rate of 2.6 percent, which resulted from a single case of
minor stroke. We attribute this low complication rate to several
factors including careful attention to pre-procedure
anti-platelet therapy, meticulous attention to procedure
protocol and routine use of cerebral protection devices. This
latter factor has been associated with a reduction of procedure
stroke rates by 50 percent when compared to non protected
procedures.14
Several questions remain regarding the utility of the carotid
angioplasty and stenting as a potential competitor or
replacement therapy for carotid endarterectomy. The cost
analysis of carotid artery stenting has not been reported to
date and may significantly influence the utility of this
procedure. Currently, the major high end cost factors involved
in the stenting procedure include dedicated self-expanding
nitinol stents costing $2,000 to $2,500 per stent. This
represents a doubling in the cost of non-dedicated nitinol
stents used for other peripheral indications. At the time of
this writing, one device (ACCULINK, Guidant Inc.) has been
approved specifically for carotid indications by the FDA. It is
likely that several additional devices will receive a similar
indication within the next six months, which may reduce device
costs. Furthermore, the current standard of care in this area
requires the use of cerebral protection devices. Most commonly,
these are filtration devices that are temporarily deployed in
the distal internal carotid artery during the procedure in an
effort to minimized cerebral embolization. The ACCUNET device
manufactured by Guidant, Inc. has received FDA approval
specifically for this application. The cost of this device
ranges between $1,500 to $2,000. Thus, the addition of these two
devices in the management of this disease will substantially
alter the cost of a therapeutic carotid intervention, which is
currently one of the most commonly performed vascular surgical
interventions in the United States today.
A second issue revolves around the durability of angioplasty
in relationship to carotid endarterectomy. Currently, long-term
studies assessing the degree of restenosis following
intervention remain limited. Lai, et al15 has recently reported
that the restenosis rate for carotid angioplasty is 6.4 percent
at 60 months, which is comparable to the restenosis rate of
carotid endarterectomy. However, additional long-term data will
be required to fully assess this aspect of this procedure.
At the present time, the Center for Medicare Services has
approved this procedure for reimbursement although specific
inclusion criteria remain limited to symptomatic patients
exhibiting 70 percent or greater stenosis.16,17 Nonetheless,
numerous educational facilities are now offering training
programs in carotid angioplasty and it is expected that there
will be a major shift in the management of carotid stenosis.
Currently, approximately 120,000 carotid endarterectomies are
performed annually in the United States. In view of the greater
applicability of this procedure to high-risk patients, it
appears likely that the volume of carotid angioplasties will
eventually exceed this number if this procedure is fully
embraced by the medical community and reimbursement is extended
to include the same patients who are eligible for carotid
endarterectomy.
References
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J Vasc Surg. 2003 Dec;38(6):1162-8.
16.
http://www.cms.hhs.gov/med/viewdraftdecisionmemo.asp?id=128.
17. Decision memo for Carotid Artery Stenting (CAG-00085R),
Center for Medicare Services. |
