Carotid Artery Angioplasty/ Stenting: Current Status by Mark S. Schechter, M.D. and John M. Doemeny, M.D., Co-Directors, Department of Interventional Radiology, Scripps Mercy Hospital
(Published in the San Diego Physician November/December 1999)

The worldwide-published case experience of carotid angioplasty is approximately 3,000, which is relatively small compared to carotid endarterectomy (CEA). In his 1998 global review of 2,048 cases of carotid artery stenting, Wholey reported a technical success rate of 98.6%, a minor stroke rate of 3%, and a major stroke rate of 1%. Although the long-term results are not known, these results demonstrate that the procedure is technically feasible with an acceptable level of safety, given the relatively early stage of development of the procedure.

Although there has not yet been a randomized, multicenter trial comparing carotid stenting to CEA, the reported results to date are quite remarkable when one considers the following: (1) Carotid Stenting is in a very early stage of development, and both technique and devices will continue to improve; and (2) Most of the patients undergoing carotid stenting are high-risk for surgery.

The benefits of CEA over medical therapy for severe carotid stenosis have been demonstrated in several large, randomized trials including the North American Symptomatic Carotid Endarterectomy Trial (NASCET), the European Carotid Surgery Trial (ECST) and the Asymptomatic Atherosclerotic Surgery Trial (ACAS). However, the patients in whom CEA has been proven to be benefical were carefully selected in these trials. Patients with many common risk factors were excluded, including age above 79, major organ failure, cardiac valvular disease or rhythm disorder, angina or myocardial infarction in the previous 6 months, previous CEA, or major surgery within 30 days. Thus, many patients have high-risk carotid lesions that do not meet the inclusion criteria for these trails and for whom the risks of CEA have not been established. The perioperative stroke rate in the NASCET study was 5.8%.

In response to a strong clinical demand from many specialists at our institution who care for high-risk patients with carotid artery disease, including vascular surgeons, we began performing this procedure in high-risk patients at Scripps Mercy Hospital in December 1997, under the auspices of the Scripps Investigational Research Board (IRB) and according to a multidisciplinary protocol. Although several San Diego County hospitals have experience with carotid angioplasty/stenting, the authors have one of the largest local series and have performed 19 carotid angioplasty/stent procedures with 18 technically successful cases (95%).

Of the 18 successful patients, 16 received stents and two patients with fibromuscular dysplasia underwent balloon angioplasty only without stent placement. There has been no perioperative TIA's or strokes (0%), one re-stenosis at 6 months (5%), and one 30-day perioperative death from cardiorespiratory failure (5%) which was unrelated to the stent procedure. Carotid stenosis etiologies in our group included arteriosclerosis (n=9), recurrent post-CEA stenoses (n=3), irradiated neck (n=3), fibromuscular dysplasia (n=3), and carotid dissection (n=1).

The procedure is performed in an interventional radiologic angiographic suite with local anesthesia and minimal conscious sedation. Because there is no general anesthesia, there is easy communication with the patient throughout the procedure, which permits serial assessment of neurologic status.

Patients may be discharged with 24 hours after the procedure. Under our protocol, all patients undergo pre- and post-procedure examination by a neurologist using the NIH Stroke Scale. We give antiplatelet therapy and intraprocedural heparin to prevent strokes during and following the procedure. Transient bradycardia and hypotension is frequently observed during balloon inflation of proximal internal carotid lesions, due to stimulation of the adjacent carotid body. This has been successfully managed by prompt balloon deflation and, if necessary, intraprocedural atropine. Post-procedure imaging follow-up consists of color flow duplex doppler every 6 months which provides exquisite imaging of the stented carotid. Magnetic resonance angiography is employed for follow-up of those lesions not well evaluated by duplex doppler, such as the high cervical carotid artery.

Which patients should be considered for carotid artery angioplasty and stenting? Certain subgroups of patients could benefit from this procedure that are at high risk for CEA-related complications. These groups include those patients with one or more significant medical comorbidities, such as severe CAD and unstable angina requiring CABG, those patients who are at risk for carotid artery clamping, such as those with contralateral carotid artery occlusion, and those patients with lesions difficult to access surgically, such as postendarterectomy restenosis, radiation-induced carotid stenosis, and very high extracranial cervical and intracranial internal carotid stenoses.

Although clinical experience to date does not address this issue, one additional high-risk patient subgroup for carotid artery stenting may be the acute stroke patient with significant carotid stenosis. Currently, CEA (or any surgical procedure) must be delayed for several weeks following an acute stroke presentaiton. While waiting for the recent stroke to "mature", the patient is at risk for further stroke, which cannot be completely prevented with medical management. Since angioplasty/stenting may be performed without the risks of general anesthesia, this procedure culd eventually become the immediate procedure of choice in a common and frustrating clinical situation.

In conclusion, published experience to date has demonstrated the technical feasibility of carotid artery angioplasty/stenting with a high technical success rate and a low major stroke rate in a relatively small number of patients compared to those reported with CEA. In the hands of experienced, qualified operators, carotid angioplasty and stenting is now a reasonable alternative to CEA for high-risk patients, in whom the complications of CEA may exceed the benefits. However, before this procedure is broadly applied to lower-risk carotid lesions, further evaluation of the procedure and related devices by large-scale, prospective, randomized trials is necessary. Such a multi-center controlled clinical trial (Carotid Revascularization Endarterectomy vs. Stent Trial or CREST) is underway and will compare the relative efficacies of carotid angioplasty/stenting and CEA in symptomatic carotid stenosis.

Virtually all of the catheter, balloon and stent technologies used in the published carotid angioplasty/stenting studies were adapted from peripheral and coronary applications. Technologies designed specifically for carotid applications are not widely available. Future developments in stent technology and development of carotid-specific stents will undoubtedly further decrease thromboembolic events and restenosis rates. Such examples include coated thromboresistant, biodegradable, and anti-proliferative radioactive stents. In addition, since virtually all periprocedural strokes are due to embolization of thromboembolic material, there is much interest in various embolic protection devices such as occlusion balloon aspiration-suction systems and guidewire-based filter-trapping devices.

Along with the recent intense interest in extracranial carotid stenting, there are similar exciting developments occurring in the intracranial cerebrovascular tree. Intracranial carotid angioplasty/stent placement for atherosclerotic disease and post-operative vasospasm, and transcatheter intra-arterial thrombolytic therapy in the intracranial carotid, middle cerebral and vertebrobasilar arterial systems of acute stroke patients are all currently technically feasible, with some initial experience reported. These and other interventional techniques hold much promise for the near future.

Note: Since the submission of this article, the authors have performed two additional successful carotid stenting procedures for a total of 21 cases performed without a neurologic complication REFERENCES:
1. Becker GJ. Current and Future Treatment of Carotid Bifurcation Atherosclerotic Disease: A Perspective. JVIR 1997;8:3-8.

2. Carotid Revascularization Endarterectomy vs. Stent Trial (CREST) Protocol. Division of Vascular Surgery, UMDNJ-New Jersey Medical School, Newark, New Jersey.

3. del Zoppo GJ, et al. PROACT: A Phase II Randomized Trial of Recombinant Pro-Urokinase by Direct Arterial Delviery in Acute Middle Cerebral Artery Stroke. Stroke 1998; 29:4-11.

4. Journal of Vascular and Interventional Radiology 24th Annual Scientific Meeting Syllabus, March 1999.

5. Wholey MH, et al. Current Global Status of Carotid Artery Stent Placement. Cathet Cardiovasc Diagn 1998;44:1-6..