Current Problems in Cardiology ® Volume 26 Number August 2001 Diagnosis and Management of Carotid Artery Disease: The Role of Carotid Artery Stenting Suhail Allaqaband, MD Cardiovascular Disease Fellow University of Wisconsin Medical School Milwaukee, Wisconsin Ramagopal J Tumuluri, MD Cardiovascular Disease Fellow University of Wisconsin Medical School Milwaukee, Wisconsin Anil Kumar Goel, MD Cardiovascular Disease Fellow University of Wisconsin Medical School Milwaukee, Wisconsin Kiran Kashyap, MD Interventional Cardiology Fellow University of Wisconsin Medical School Milwaukee Wisconsin Anjan Gupta, MD, FACC Associate Director Cardiovascular Disease Fellowship Training Program and Clinical Instructor of Medicine University of Wisconsin Medical School Milwaukee, Wisconsin Tanvir K Bajwa, MD, FACC, FSCAI Director of the Peripheral Vascular Disease and Cardiac Catheterization Laboratories Milwaukee Heart Institute of Sinai Samaritan Medical Center and Clinical Associate Professor of 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Back issues generally are available for the previous years Copyright Copyright © 2001 by Mosby, Inc All rights reserved No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means—electronic, mechanical, photocopying, recording, or otherwise—without prior written permission from the publisher, except in cases described below This journal has been registered with the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923 Consent is given for the copying of articles for personal or internal use of specific clients This consent is given on the condition that the copier pay directly to the CCC the base fee of $35.00 per article for copying beyond that permitted by U.S Copyright Law: 0146-2806/2001 $35.00 This consent does not extend to other kinds of copying, such as for general distribution, resale, advertising, and promotional purposes or for creating new collective works All inquiries regarding copyrighted material from this publication other than those that can be handled through the CCC should be directed, in writing, to Journals Permission Department, Mosby, 6277 Sea Harbor Dr, Orlando, FL 32887; fax (407) 345-4058 Indexing Current Problems in Cardiology is listed in Index Medicus, Current Contents/Clinical Medicine, and SCI Disclaimer Statements and opinions expressed herein are those of the author(s) and not necessarily those of the editor(s) or publisher The editor(s) and publisher disclaim any responsibility or liability for such material and not guarantee, warrant, or endorse any product or service advertised in this publication, nor they guarantee any claim made by the manufacturer of such product or service Current Problems in Cardiology ® Diagnosis and Management of Carotid Artery Disease: The Role of Carotid Artery Stenting Foreword 497 Scope of the Problem: Prevalence and Epidemiology 499 499 500 Pathologic Study Symptoms Increase Risk Diagnosis of Carotid Artery Stenosis Noninvasive Tests Other Noninvasive Tests Invasive Tests Choice of Imaging Study Medical Therapy Antiplatelet Agents Anticoagulants Surgical Management of Carotid Artery Disease Trials of CEA in Patients with Symptoms Symptom-free Patients Nonsurgical Treatment of Carotid Artery Stenosis Percutaneous Balloon Angioplasty for Carotid Artery Disease Carotid Artery Stenting Simultaneous Carotid and Coronary Artery Interventions Carotid Artery Stenosis With Contralateral Occlusion Carotid Artery Stenosis with Prior Radiation Exposure Carotid Artery Stenting in Restenotic Lesions after Endarterectomy Carotid Artery Stenting for Bilateral Carotid Artery Stenosis Carotid Artery Stenting for Surgically Inaccessible Lesions Curr Probl Cardiol, August 2001 502 502 504 504 506 507 507 508 508 508 510 513 513 515 519 520 521 522 527 531 495 Carotid Artery Stenting for Takayasu’s Arteritis 532 Carotid Artery Stenting In Octogenarians 534 Complications Associated with Extracranial Carotid Artery Intervention 536 New Therapies and Devices in Carotid Artery Stenting Intravascular Ultrasonography Use of Glycoprotein IIb/IIIa Receptor Inhibitor Protection Devices Approaches and Devices for Cerebral Protection Distal Occlusion Balloon Filtration Device Placed Distal to the Lesion Proximal Occlusion Balloon 537 537 539 541 541 541 543 543 Carotid Artery Stenting: Ongoing and Future Trials 544 Conclusion 547 References 548 496 Curr Probl Cardiol, August 2001 Foreword In the August issue of Current Problems in Cardiology, Dr Bajwa and his colleagues from the Milwaukee Heart Institute and the University of Wisconsin Medical School in Milwaukee provide a comprehensive discussion of the role of carotid artery stenting in the management of patients with carotid artery disease They discussed the noninvasive and invasive demonstration of carotid artery disease and the treatment of patients with this relatively common clinical problem by medical therapy, surgical management, and percutaneous catheterization techniques Dr Bajwa and his colleagues have had considerable experience in treating large numbers of patients with carotid artery stenting, and they provide an extremely informative discussion of the indications, contraindications, and results of coronary artery stenting in various groups of low- and high-risk patients I am grateful to Drs Allaqaband, Tumuluri, Goel, Kashyap, Gupta, and Bajwa for their contribution to this month’s monograph Robert A O’Rourke, MD, FACC, MACP Editor in Chief Curr Probl Cardiol, August 2001 497 Dr Tanvir Bajwa is Director of the Peripheral Vascular Disease and Cardiac Catheterization Laboratories at the Milwaukee Heart Institute of Sinai Samaritan Medical Center in Milwaukee He is a clinical associate professor of medicine at the University of Wisconsin Medical School—Milwaukee clinical campus and is currently involved in the SAPPHIRE and ARCHER trials of carotid artery stenting Dr Anjan Gupta is the associate director of the cardiovascular disease fellowship training program and a clinical instructor of medicine at the University of Wisconsin Medical School— Milwaukee clinical campus Dr Suhail Allaqaband is a cardiovascular disease fellow at the University of Wisconsin Medical School—Milwaukee clinical campus Dr Anil Goel is a cardiovascular disease fellow at the University of Wisconsin Medical School—Milwaukee clinical campus Dr Ramagopal Tumuluri is a cardiovascular disease fellow at the University of Wisconsin Medical School— Milwaukee clinical campus Dr Kiran Kashyap is a fourth-year interventional cardiology fellow at the University of Wisconsin Medical School—Milwaukee clinical campus 498 Curr Probl Cardiol, August 2001 Diagnosis and Management of Carotid Artery Disease: The Role of Carotid Artery Stenting Scope of the Problem: Prevalence and Epidemiology very year in the United States, stroke kills 160,000 people and accounts for of every 15 deaths, making it the third leading cause of death behind heart disease and cancer.1 Each year, about 600,000 have a new or recurrent stroke, of which approximately 500,000 are first attacks and 100,000 are recurrent attacks Stroke strikes men and women equally, although at all ages, more women than men die of stroke On the basis of the National Heart, Lung, and Blood Institute’s Atherosclerosis Risk in Communities study’s2 ageadjusted annual incidence rate for stroke, it affects 1.78 white men, 4.44 black men, 1.24 white women, and 3.10 black women in every 1000 each year Overall, the risk of a first stroke is 38% greater for black people than for white people.3 E Pathologic Study In the Framingham Heart Study, the most common type of stroke was atherosclerotic brain infarction, which accounted for 61% of all strokes, excluding transient ischemic attacks (TIAs) In the National Heart, Lung, and Blood Institute’s Atherosclerosis Risk in Communities study,2 83% of all strokes were ischemic, of which 38% were lacunar, 14% were thromboembolic, and the remainder were large artery strokes In the 1950s, most brain infarctions were attributed to intracranial arterial occlusion.4 Over the years, Fisher et al have studied the pathophysiologic condition and clinical presentation of strokes, leading to greater understanding of the importance of intracranial arterial disease They identified the most common sites as the carotid bifurcation, the internal carotid arteries, and the proximal vertebral arteries.5,6 Clinical Presentation The clinical manifestations of carotid artery disease are carotid bruit and symptoms caused by cerebral ischemia; however, a patient may have significant carotid artery stenosis without any signs or symptoms Carotid bruit Although cervical bruit is an important sign of carotid artery disease, in a series of 331 patients referred to a neurology clinic in Curr Probl Cardiol, August 2001 499 which half had a carotid bruit, only 37% had a high-grade lesion on carotid artery duplex ultrasound scanning.7 In an analysis of patients enrolled in the North American Symptomatic Carotid Endarterectomy Trial (NASCET),8 findings of a focal ipsilateral carotid bruit had a sensitivity of 63% and specificity of 61% for high-grade stenosis, with a higher yield in patients with symptoms, 75% of whom had moderate-to-severe stenosis on diagnostic testing The Framingham Heart Study showed that in symptom-free patients a carotid bruit doubled the risk of stroke.9 In another population-based study, in patients who had a bruit, the annual rate for all primary vascular events was 11% if the stenosis was >50% and only 4.2% if the stenosis was 50%) internal carotid artery stenosis increased from 4.4% in those who had never smoked to 7.3% in former smokers and 9.5% in current smokers (P < 0001) Inflammation and chronic infection Recent evidence suggests that inflammation and systemic infection play a role in atherosclerosis.32 In a clinical study of asymptomatic carotid artery atherosclerosis, it was found that Chlamydia pneumonia strain TWAR had a significant cross-sectional association This organism may be a contributor to the pathogenesis of atherogenesis in carotid artery disease.33 Patients who have more than one of these risk factors multiply their chances for development of severe carotid artery stenosis.34 Diagnosis of Carotid Artery Stenosis Diagnosis of carotid artery disease begins with careful history-taking and thorough physical examination, followed as appropriate by one or more of the diagnostic tests described below Currently available modalities that help confirm a diagnosis of carotid artery disease include both invasive tests, such as cerebral angiography, and noninvasive tests, such as carotid duplex ultrasonography (CDUS) and magnetic resonance angiography (MRA) Noninvasive Tests Carotid Artery Duplex Ultrasonography Combining B-mode ultrasound imaging and Doppler ultrasonography to detect carotid artery stenosis, CDUS is currently the most widely used noninvasive test for carotid artery stenosis B-mode ultrasound scanning typically displays, in real time, a longitudinal section of the carotid artery, including the common carotid artery, the bifurcation of the carotid artery, and the internal and external carotid arteries Doppler ultrasonography helps to evaluate flow in the carotid artery and thus, on the basis of predetermined parameters of flow velocity, helps to estimate the degree of stenosis CDUS is not only safe because it is noninvasive, but it is also portable and inexpensive Moreover, CDUS can be used to study the composition of the atherosclerotic plaque The sensitivity, specificity, and overall accuracy of CDUS are well defined in the literature Suwanwela et al35 showed that findings of a peak systolic velocity of >440 cm/s had a sensitivity of 58%, an end-diastolic 502 Curr Probl Cardiol, August 2001 in patients with hypertension Another concern is that GPIIb/IIIa agents might convert small, clinically insignificant embolic infarcts into hemorrhagic infarcts Our current practice is not to use these agents routinely during carotid artery stenting There might be a subset of patients who could benefit from these agents; however, this needs to be defined further in clinical trials Protection Devices Presumably, the main cause of perioperative neurologic deficit after carotid artery PTA and stenting is release of embolic particles from the carotid artery plaque during balloon dilation and stent deployment CAVATAS,135 a randomized, prospective trial that compared the safety and efficacy of CEA with that of carotid angioplasty (with and without stenting), has yielded interesting preliminary results On average, balloon angioplasty produced times more high-density signals (hits), representing embolic particles (including air) that were detected by transcranial Doppler ultrasonography than did CEA Several authors have qualitatively and quantitatively analyzed intraluminal material released during carotid artery procedures During carotid artery stenting, Theron et al 136 found cholesterol crystals of 600 to 1300 µm in diameter in 17 of 21 samples collected Martin et al137 reported lipoid masses raging from 26 to 600 µm in addition to the cholesterol crystal (3.7 to 500 µm) Ohki et al138 used human carotid artery plaque specimens to study embolic debris and identified particles from 50 to more than 1000 µm in diameter, but the vast majority were 100 to 500 µm Although small particles (90% stenosis) produce higher numbers of embolic particulates, but they found a low risk of embolization when plaques were restenotic, hyperechoic, and concentric They observed that every plaque generates some embolic material Approaches and Devices for Cerebral Protection There are different approaches for cerebral protection:140,141 distal occlusion balloon, distal filter, and proximal occlusion balloon Distal Occlusion Balloon The GuardWire (PercuSurge, Inc, Sunnyvale, Calif) is a prototype distal occlusion balloon cerebral protection device that is used to temporarily Curr Probl Cardiol, August 2001 541 occlude outflow from the distal ICA The GuardWire temporary occlusion wire is hollow and has an elastomeric occlusion balloon located at the proximal end of the distal tip Once the lesion is crossed, an inflation device is attached to the proximal end of the GuardWire, and the occlusion balloon is inflated The inflation device is then removed from the proximal end of the GuardWire, whereas the occlusion balloon remains inflated, thus providing a coaxial exchange capability for balloon and stent delivery catheters Any embolic debris released during angioplasty and stenting remains in the ICA and is aspirated through the large lumen of the export catheter at the end of the procedure The advantages of this system are its lower crossing profile and flexibility (compared with filtration devices) and its complete protection of the distal ICA Its disadvantages are interruption of flow during protection, which might cause cerebral ischemia, especially in patients who have occluded contralateral carotid arteries; the cumbersomeness of the procedure; the inability to perform angiography during balloon protection; difficulty in crossing tight or tortuous lesions; the risk that particles may embolize to the the brain via a patent external carotid artery; and risk of causing spasm and dissection in the distal ICA In the SAFER trial,142 which evaluated the efficacy of the PercuSurge GuardWire in the treatment of degenerated saphenous vein graft used for CABG, this device reduced major adverse clinical events by 50% compared with the control arm SAFER is the first to show the clinical benefit of recovering emboli by use of a distal protection device during endovascular procedures.142 Henry et al143 reported on 48 patients at high risk who underwent carotid PTA and stenting via femoral approach in whom a 0.014-inch GuardWire balloon occlusion device was used for cerebral protection The mean stenosis in treated arteries was 82.1% ± 9.65%: 33 (62%) lesions were calcified, 38 (72%) were ulcerated, and 32 (60%) were asymptomatic Their immediate technical success rate was 100% Carotid artery occlusion was well tolerated in all except one patient who had multiple, severe carotid artery lesions and poor collateralization The mean cerebral flow occlusion time was 346 ± 153 seconds during predilation and 303 ± 143 seconds during stent placement, for a mean total of 542 ± 243 seconds of flow occlusion There was one transient neurologic complication (amaurosis) in a patient who had anastomosis between the external and ICA territories The mean diameter of debris removed in all patients was 0.8 mm These investigators concluded that the GuardWire device is safe and effective in protecting the brain from cerebral embolism, although larger studies were warranted 542 Curr Probl Cardiol, August 2001 Filtration Device Placed Distal to the Lesion The Angioguard (Cordis, Warren, NJ) device is a temporary, percutaneous transluminal intraarterial filtration system that is designed to conform to the vessel lumen and to capture emboli produced during carotid angioplasty and stenting while maintaining flow The filtration umbrella (a preshaped Nitinol expansion system) is mounted on the distal tip of the 0.014-inch guide wire and has multiple perfusion pores After the filter guide wire, which is encapsulated in the delivery catheter, is passed through the carotid artery lesion, the delivery catheter is retracted, deploying the filter in the distal ICA After the angioplasty and stenting is completed, a retrieval catheter is used to retrieve the Angioguard The catheter envelops the filtration element along with the captured embolic debris The advantages of this system are preservation of flow and the ability to perform angiography during the procedure Its disadvantages are the risk of missing small particles, its larger crossing profile, the difficulty in crossing tight or tortuous lesions, the need to keep the wire extremely stable during catheter exchange, and the risks of causing spasm and dissection, as well as a risk that the filter itself may induce thrombosis Proximal Occlusion Balloon The Parodi anti-embolization catheter (PAEC) (ArteriA, San Francisco, Calif) is a guiding catheter that has an occlusion balloon attached at the distal end and a main lumen internal diameter of 7F for passage of balloons and stents Once the PAEC is inserted in the CCA, a Parodi external balloon (ArteriA) is inserted and inflated in the ECA Next, the occlusion balloon, which is attached on the outer surface of the PAEC, is inflated, occluding inflow to the carotid bifurcation while maintaining access to the carotid bifurcation lesion through the main lumen The side port of the PAEC is then connected to a sheath that is inserted percutaneously into the femoral vein to create a temporary arteriovenous shunt This shunt creates the flow reversal in the ICA Once reversed flow is established, carotid angioplasty and stenting can be performed safely because any sized plaque material flowing through the PAEC is captured by a filter that is placed between the artery-vein connection At the time of this review, 90 carotid artery stenoses have been treated under PAEC protection worldwide, each case has been technically successful, and all patients have tolerated the occlusion and flow reversal No patient had an embolic neurologic event Advantages of this system are the affording of complete protection before treating the lesion, its ability to capture particles of all sizes, its Curr Probl Cardiol, August 2001 543 ability to treat tight and tortuous lesions (because there is no need for a relatively bulky and stiff system to be passed through the artery), and the freedom to choose any guide wire Its disadvantages are flow interruption during protection, the risk of causing dissection or spasm in the ECA or CCA, and the need to have a larger groin puncture for entry The unavoidable drawback to all occlusive–type protection devices is the impact on cerebral perfusion Patients generally tolerate ICA occlusion well for several minutes without discomfort; but severe contralateral carotid artery stenosis or an anomalous circle of Willis that impedes collateral flow makes such tolerance very difficult Hence, all patients must undergo complete preprocedural 4-vessel cerebral angiography to identify any congenital or pathologic contraindications to balloon occlusion Carotid Artery Stenting: Ongoing and Future Trials Still a relatively new procedure, carotid artery stenting has gained popularity for managing carotid artery stenosis because it is less invasive than CEA, but there are little data from randomized trials that compare the efficacy of these two procedures Although most current reports are of nonrandomized trials and clinical case series, in the United States and worldwide, several prospective, randomized trials are underway to determine the role of carotid artery stenting in treating patients who have high-grade carotid artery stenoses The Carotid Revascularization Endarterectomy vs Stent Trial is a prospective, randomized 60-center trial that compares traditional CEA with stent-assisted carotid angioplasty for treatment of carotid artery stenosis to prevent recurrent strokes Its planned enrollment is 2500 patients who have had a TIA or a mild stroke The Carotid Revascularization Endarterectomy vs Stent Trial will randomly assign patients who are at a low surgical risk to undergo either CEA or stent-assisted carotid angioplasty Eligibility criteria are TIA, amaurosis fugax, or nondisabling stroke occurring within 180 days of randomization and ipsilateral carotid artery stenosis >50% by angiography or 70% by ultrasonography Patients will be monitored for up to years with clinic visits at 1, 6, 12, 18, 24, 30, 36, 42, and 48 months Primary end points are stroke, MI, or death during a 30-day periprocedural period or ipsilateral stroke within 30 days thereafter Secondary end points are comparison of 30-day morbidity and mortality rates, long-term morbidity and mortality rates, restenosis rates, and cost-effectiveness of the two treatment strategies The Stenting and Angioplasty with Protection in Patients at High-Risk for Endarterectomy Trial (SAPPHIRE) is a prospective, randomized trial at 30 centers with a planned enrollment of 600 to 900 patients at high risk 544 Curr Probl Cardiol, August 2001 who have carotid artery disease SAPPHIRE compares CEA with the Cordis Nitinol carotid artery stent and delivery systems combined with an AngioGuard distal protective device A parallel stent registry of 400 patients will include those patients who meet the inclusion criteria but are determined by the surgeon at each study site to be at too high a risk for CEA and therefore inappropriate for randomization Similarly, a separate registry will be maintained of those patients who are deemed to be at high risk for carotid artery stenting by the interventionalist and thus cannot be randomly assigned to the carotid artery stenting group Patients will be monitored with clinical visits at 30 days, months, year, and then yearly for years Carotid artery duplex ultrasound scanning will be performed at 48 hours and months and then annually If ultrasonography reveals stenosis, the patients will undergo angiography Eligible patients must have had clinical symptoms within the previous 180 days and have had either one or more TIAs with clearing of signs and symptoms 24 hours with stenosis >50% (by ultrasound scanning) of the CCA or ICA Others who are eligible must have a >80%-diameter stenosis of the ICA or CCA without neurologic symptoms or one or more of the following: class III or IV CHF and LVEF 24 hours and 50% on angiography within the previous 180 days and have had one of the following: TIA, amaurosis fugax, or minor/nondisabling stroke (in the hemisphere supplied by target vessel) within 180 days of enrollment or be symptom free with >80% carotid artery stenosis on angiography and able to meet clinical inclusion criteria Patients will be monitored with clinical visits at 1, 6, and 12 months and annually thereafter for years They will undergo carotid artery duplex ultrasonography at 1, 6, and 12 months; a neurologic examination at and months, fill out a TIA/stroke questionnaire, and report adverse events by telephone at 18, 24, and 36 months Angiography will be performed if duplex scanning at or 12 months shows >80% stenosis in the treated artery Primary end points are stroke, death, and MI at 30 days and ipsilateral stroke at 12 months Secondary end points are target lesion revascularization at and 12 months; evaluation of treated segment by CDUS at 6, 12, and 24 months; acute success; access site complications; and medical resource use The International Carotid Stenting Study ICSS (CAVATAS-2) is a prospective, randomized multicenter trial (planned enrollment of 2000 patients) CAVATAS-2 compares the risks and benefits of traditional CEA with those of primary carotid artery stenting for preventing stroke and, if approved by the steering committee, may incorporate new designs of stents, filters, and protection devices to track new technology Eligibility criteria are recent symptomatic severe carotid artery stenosis suitable for primary stenting and surgical CEA as demonstrated by audited noninvasive or digital subtraction angiography Primary outcome will be survival free of death or stroke, and secondary outcome will be stroke, MI, or death within 30 days of treatment, treatment-related cranial nerve palsy, or hematoma, restenosis (>70%) on ultrasound follow-up, and economic quality of life The Stenting of High Risk Patients Extracranial Lesions Trial with Emboli Removal is a single-arm, prospective, multicenter study at 30 centers (planned enrollment 400 patients) The Stenting of High Risk Patients Extracranial Lesions Trial with Emboli Removal study will compare CEA with the advantages of use of a carotid artery stent with a distal protection device (GuardWire) for preventing stroke 546 Curr Probl Cardiol, August 2001 Conclusion As the third leading cause of death in the United States, stroke is a major medical problem that merits increasing concern because its rise accompanies the “graying of America” that is imminent now that the baby boomer generation becomes a larger segment of the elderly population Medical management and risk modification will be important; however, in patients found to have high-grade carotid artery stenosis, medical management is not enough CEA is still the gold standard for treating carotid artery stenosis NASCET, ECST, and ACAS have shown that CEA clearly is better than medical management alone in patients both with and without symptoms who have high-grade stenosis On the other hand, carotid artery stenting is a relatively new procedure that is attractive because it is less invasive, avoiding morbidity associated with CEA Studies have shown carotid artery stenting to be highly effective with a low risk of stroke and death, even in patients considered to be at high surgical risk Moreover, it has been effective in patients whose anatomy prohibits CEA Although restenosis is a major limitation of percutaneous intervention in coronary and peripheral arteries, in the era of self-expandable stents, restenosis is not a problem in large-caliber carotid arteries In large cohort-based studies, rates of restenosis have been 2% to 5% With regard to short- and long-term risk of stroke, CEA and carotid artery stenting have been shown to be comparable, and we believe that the risk could be reduced even more with widespread use of distal protection devices Extensive data from centers worldwide show that carotid artery stenting is a viable alternative to CEA, leading to head-to-head comparison of the two procedures in large multicenter randomized trials If results seen in nonrandomized studies hold true even in randomized trials, carotid artery stenting could become the new “gold standard” for patients who have high-grade carotid arterial stenosis Data from these trials are eagerly awaited Until then, CEA will continue to be the standard of care for patients whose surgical risk is rated low to average At this time, carotid artery stenting should be reserved for patients enrolled in randomized trials or patients at such high risk as follow: patients with poor cardiopulmonary condition (class III or IV congestive heart failure, LVEF < 30%, heart surgery within the past weeks, recent MI [>24 hours and