Carotid Artery Angioplasty and Stent Placement

Carotid Artery Angioplasty and Stent Placement: Quality Improvement Guidelines to Ensure Stroke Risk Reduction John J. Connors, III MD, David Sacks, MD, Gary J. Becker, MD, and John D. Barr, MD J Vasc Interv Radiol 2003; 14:S317–S319 Abbreviations: AHA � American Heart Association, CAS � carotid artery stent placement, CEA � carotid endarterectomy. CERVICAL carotid atherosclerotic ste- nosis has been correctly surmised to be a potentially preventable cause of stroke for a half-century. For most of this time, neither the absolute risk of the condition nor the specific contrib- uting factors were known. Not sur- prisingly, therefore, medical therapy was poorly understood and offered a limited armamentarium. Prior dogma maintained that medical therapy alone neither significantly affected the pro- gression of atherosclerosis nor caused its regression. Today an extensive body of literature confirms that cervi- cal carotid artery atherosclerosis is common, relatively easy to evaluate, a major health threat, and surgically cor- rectable. The appropriateness of ca- rotid endarterectomy (CEA) has been evaluated by at least seven random- ized trials, and further study is war- ranted and ongoing. While great strides have been made in the last de- cade in understanding cervical carotid atherosclerotic stenosis, there are still many important unknowns concern- ing the clinicopathologic condition, its various manifestations, precipitating biochemical and pathophysiologic events, specific patient risk character- istics, optimal medical therapy, as well as indications for, and best methods of, surgical and interventional thera- pies. Perhaps one of the best examples of the evolutionary nature of knowledge in this field is the relatively new con- cept that the principal culpability for clinical neurologic events is not the “degree-of-stenosis” per se, but rather the pathology of the plaque and the ischemia produced by atherothrom- botic emboli. This belief is universally accepted in the cardiovascular com- munity but seems to be under-appre- ciated in the neuroscience community. The ultimate confirmation of this con- cept is the 10-fold or greater difference in risk for someone with an 80% “non- embologenic” (ie, “asymptomatic”) ca- rotid stenosis as compared to an 80% “embologenic” (symptomatic) steno- sis. For the former there is about 1% to 2% per year stroke risk from the lesion itself as compared to the latter, which has about 10% to 20% risk of stroke in the first year (1,2). Further, recent studies of newer pharmacologic agents including anti- platelet agents (such as clopidogrel) and plaque-stabilizing agents (such as HMGCoA-reductase inhibitors [“statins”] and angiotensin converting enzyme [“ACE”] inhibitors) do indeed demonstrate that the natural history of atherosclerotic plaques can be posi- tively influenced in a way that changes the risk/benefit ratio of all therapies for not only coronary athero- sclerosis but also for carotid athero- sclerosis (3,4). However, none of these new medical therapies have been sys- tematically compared to CEA or ca- rotid artery stent placement (CAS) in controlled clinical trials aimed at eval- uating the best method to reduce stroke and stroke-related morbidity and mortality. In March 2000, the American Soci- ety of Interventional and Therapeutic Neuroradiology (ASITN), the spe- cialty organization then composed pri- marily of neuroradiologists and neu- rosurgeons most involved with cervico-cerebral angiography and cer- vical and intracranial endovascular in- tervention, published a review and analysis of the current literature on carotid atherosclerosis and its treat- ment (5). Since that time, continued progress has been made in further un- derstanding the nature of carotid ath- erosclerosis, improving surgical tech- niques, advancing the pharmaceutical armamentarium, and refining a poten- tial endovascular therapy: carotid ar- tery angioplasty and stent placement. Three medical societies that include training in cervico-cerebral angiogra- phy as part of their ACGME defined residency programs, the ASITN, the American Society of Neuroradiology (ASNR), and the Society of Interven- tional Radiology (SIR), recognize the importance of carotid atherosclerosis and its appropriate management. In this issue of the Journal of Vascular and This article also appears in J Vasc Interv Radiol 2003; 14:1095–1097. From the Miami Cardiac and Vascular Institute, Miami, FL (J.J.C., G.J.B.), Department of Radiology, Reading Hospital and Medical Center, Reading PA (D.S.), and Mid-South Imaging and Therapeutics, Memphis, TN (J.D.B.). Received July 3, 2003; ac- cepted August 6. Address correspondence to J.J.C., MCVI, 8900 Kendall Dr, Miami, FL 33176. E-mail budmancon@aol.com J.J.C. and J.D.B. have identified a potential conflict of interest. © SIR, 2003 DOI: 10.1097/01.RVI.0000086538.86489.2 S317 Interventional Radiology, these societies have published their joint recommen- dations for appropriate quality and performance criteria for the innovative procedure of carotid artery balloon an- gioplasty and stent placement. Further documents on this topic will be forth- coming from other multispecialty writing groups including the Ameri- can Heart Association (AHA). Some may argue that quality and performance criteria for CAS are pre- mature. CAS is not currently ap- proved by Medicare for reimburse- ment outside of a Food and Drug Administration (FDA) approved study protocol. There are at present no FDA-approved carotid stents or cere- bral embolic protection devices. De- spite these restrictions, CAS is widely performed in both academic and com- munity hospital settings and this ne- cessitated the development of quality and performance guidelines at this time. The attraction of CAS is that it is minimally invasive, relies on tech- niques already present in the interven- tional endovascular community, and might produce better outcomes in those patients thought to be at higher risk of complications or poor outcome if treated with surgical endarterec- tomy. However, similar to endarterec- tomy, cerebral angiography, and coro- nary intervention—all of which have performance and training standards— there is a learning curve for perform- ing CAS, and outcomes depend on physician expertise and institutional experience as well as appropriate pa- tient selection. The stroke rates in some CAS studies are sobering (6,7). Results from the most experienced centers may not reflect the general ex- perience. Just as the AHA recognizes that carotid endarterectomy has bene- fit only if performed with a high de- gree of technical proficiency on appro- priate patients, the same holds true for carotid stent placement. Since benefit must be weighed against risk, indications for CAS have also been listed as a means of selecting patients for an adequately high bene- fit-to-risk ratio. All of these criteria are in flux. These Quality Improvement Guidelines were developed over a pe- riod of 3 years by a multispecialty group from neuroradiology, neurosur- gery, interventional radiology, and in- terventional neuroradiology. Consen- sus among the authors was reached based on the best currently available data. The results of several ongoing trials studying “high surgical risk” symptomatic and asymptomatic pa- tients, some of whom are randomized to surgery, will add further under- standing to the role of endovascular therapy in the treatment of carotid ar- tery disease. CEA for asymptomatic carotid stenosis is increasingly contro- versial, even more so now that further analysis of prior trials has been per- formed (8–10) and now that medical therapy has improved (3,4). Some might consider controversial the rec- ommendation that, at present, most patients with asymptomatic carotid stenoses not be treated with CAS out- side of trials. Although the document lists as an acceptable indication “asymptomatic patients at high surgi- cal risk,” high surgical risk produced by associated medical comorbidities does not necessarily imply a naturally occurring high risk for stroke from the “asymptomatic” lesion itself. The Asymptomatic Carotid Atherosclero- sis Study (ACAS) and the AHA deter- mined that CEA in particular, but gen- eralizable to any form of intervention, should only be performed if the risk of the procedure was less than 3% stroke and/or death; with new medical ther- apies, this number may need to be even lower (10–12). A favorable bene- fit:risk ratio for CAS in asymptomatic patients remains to be demonstrated but is certainly fertile ground for fur- ther research. Training and experience require- ments described in the Quality Im- provement Guidelines in this issue may be considered by some to be con- troversial. Experts in CAS come from many backgrounds, but fundamen- tally, all worked long and hard to ac- quire the skills, knowledge and train- ing to become experts in their own field as well as with this innovative procedure. The authors of the CAS Quality Improvement Guidelines be- lieve that patient safety should never be compromised and that “stroke” as a procedural risk warrants the highest level of skill, knowledge, and training. It is clear that extensive prior experi- ence with diagnostic catheterization and with interventions in other vascu- lar beds overlaps with the training re- quired for CAS. The document re- quires 200 diagnostic cervicocerebral angiograms for physicians without prior catheter experience, but 100 cer- vicocerebral angiograms for physi- cians with sufficient prior experience to meet the AHA training require- ments for peripheral vascular inter- ventions (13). Of note, for “peripheral” vascular intervention accreditation, the AHA training requirements spec- ify “peripheral” vascular experience regardless of prior experience in other vascular beds (13). This concept is of utmost importance when considering the unique and vulnerable nature of the brain. The choice of 100 diagnostic cervicocerebral angiography cases was derived from multiple disparate but consistent sources, including the AHA peripheral interventions guidelines (13), the peripheral vascular training documents from the SIR (14,15), the American College of Cardiology (16,17), the Society for Vascular Sur- gery (18), and the Society for Cardiac Angiography and Interventions (19– 21), as well as the multisociety neu- rointerventional training standards from the ASNR, ASITN, the American Association of Neurological Surgeons, the AANS/CNS Section on Cerebro- vascular Surgery, and the Congress of Neurological Surgeons (22). The latter document requires 100 diagnostic cer- vicocerebral angiograms prior to even entering residency/fellowship train- ing in endovascular surgical neurora- diology and was unanimously ap- proved by each and every executive committee of these five neurological societies. This consensus was based on the belief that there are challenges and dangers unique to the selection of ca- rotid arteries and performance of ca- rotid and cerebral interventions. These facts combine to necessitate mastery of catheter skills, clinical knowledge, and vascular anatomy specific to the ca- rotid and cerebral circulations. It was for these reasons that the authors chose a requirement of 100 diagnostic cerebral angiograms even with prior experience in other vascular beds. With the diminishing use of diag- nostic carotid angiography due to im- provements in noninvasive carotid imaging, both radiologists and other specialists may find it difficult to achieve this procedural training. How- ever, these Guidelines represent the consensus of the authors on the neces- sary core knowledge and skills that must be acquired by a physician to safely perform CAS without supervi- S318 • Carotid Angioplasty and Stent Placement: Stroke Risk Reduction September 2003 JVIR sion, recognizing that only a minority of the most highly trained and skilled practitioners from any background may fulfill the requirements for per- forming this procedure. CAS is almost universally an elec- tive procedure and patients can be re- ferred or transferred to a center with the personnel and experience neces- sary to perform this procedure with the high level of competence it de- serves. As stated in the Quality Im- provement document, “any procedure that has ‘stroke’ as a routine potential risk should be performed only by medical professionals with appropri- ate training and experience.” Until fur- ther validated, CAS should be re- served for suitable patients at high intrinsic risk for stroke and with high risk factors for CEA. CAS may ulti- mately offer a less invasive and safer means than CEA for reducing the risk of stroke in appropriately selected pa- tients. Further research to clarify the roles of CEA, the new “best medical therapy,” and CAS is needed and en- couraged, and should be supported by all health care professionals, specialty societies, the National Institutes of Health, and relevant foundations. It is the intended purpose of the CAS qual- ity improvement guidelines to provide physicians with the tools to measure the quality of care they provide as they consider offering this procedure. References 1. North American Symptomatic Carotid Endarterectomy Trial Collaborators. Beneficial effect of carotid endarterec- tomy in symptomatic patient with high-grade carotid stenosis. N Engl J Med 1991; 325:445–508. 2. European Carotid Surgery Trialists Collaborative Group. Risk of stroke in the distribution of an asymptomatic carotid artery. Lancet 1995; 345:209– 212. 3. Golledge J, Greenhalgh RM, Davies AH. The symptomatic carotid plaque. Stroke 2000; 31:774–781. 4. Gorelick PB. New horizons for stroke prevention: PROGRESS and HOPE. Lancet Neurol 2002; 1:149–156. 5. Connors JJ 3rd, Seidenwurm D, Wojak JC, et al. Treatment of atherosclerotic disease at the cervical carotid bifurca- tion: Current status and review of the literature. AJNR 2000; 21:444–450. 6. Diethrich EB, Ndiaye M, Reid DB, et al. Stenting in the carotid artery: Initial experience in 110 patients. J Endovasc Surg 1996; 3:42–62. 7. Jordan WD Jr, Voellinger DC, Fisher WS, et al. A comparison of carotid angioplasty with stenting versus end- arterectomy with regional anesthesia. J Vasc Surg 1998; 28:397–403. 8. Barnett HJ, Meldrum HE, Eliasziw M for the North American Symptomatic Carotid Endarterectomy Trial (NASCET) collaborators. The appro- priate use of carotid endarterectomy. CMAJ 2002; 166:1169–1179. 9. Inzitari D, Eliasziw M, Gates P, et al. The causes and risk of stroke in pa- tients with asymptomatic internal-ca- rotid-artery stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators. N Engl J Med 2000; 342:1693–1700. 10. Gebel JM, Brott TG, Howard VJ, et al. Brain injury as detected by computer- ized tomography in CT scan in ACAS [abstract]. Stroke 2003; 34:238. 11. Executive Committee for the Asymp- tomatic Carotid Atherosclerosis Study. Endarterectomy for asymptomatic ca- rotid artery stenosis. JAMA 1995; 273: 1421–1428. 12. Biller J, Feinberg WM, Castaldo JE, et al. Guidelines for carotid endarterectomy: A statement for Healthcare Profession- als from a Special Writing Group of the Stroke Council, American Heart Asso- ciation. Stroke 1998; 29:554–562. 13. Levin DC, Becker GJ, Dorros, et al. Training standards for physicians per- forming peripheral angioplasty and other percutaneous peripheral vascular interventions. A statement for Health Professionals from the Special Group of Councils on Cardiovascular Radiol- ogy, Cardio-Thoracic and Vascular Surgery, and Clinical Cardiology, the American Heart Association. Circula- tion 1992; 86:1348–1350. 14. Singh H, Cardella JF, Cole PE, et al. Quality improvement guidelines for diagnostic arteriography. J Vasc Interv Radiol 2002; 13:1–6. 15. Standards of Practice. Committee of the Society of Cardiovascular and In- terventional Radiology. Angioplasty standard of practice. J Vasc Interv Ra- diol 1992; 3:269–271. 16. Spittell JA, Nanda NC, Creager MA, et al. Recommendations for training in vascular medicine. American College of Cardiology Peripheral Vascular Dis- ease Committee. J Am Coll Cardiol 1993; 22:626–628. 17. Spittell JA, Creager MA, Dorros G, et al. Recommendations for peripheral transluminal angioplasty: Training and facilities. J Am Coll Cardiol 1993; 21: 546–548. 18. White RA, Hodgson KJ, Ahn SS, et al. Endovascular interventions training and credentialing for vascular sur- geons. J Vasc Surg 1999; 29:177–186. 19. Wexler L, Dorros G, Levin D, King S. Guidelines for performance of periph- eral percutaneous transluminal angio- plasty. The Society for Cardiac Angiog- raphy and Intervention, Interventional Cardiology Committee, Subcommitee on Peripheral Interventions. Cathet Cardiovasc Diag 1990; 21:128–129. 20. Babb JD, Collins TJ, Cowley MJ, et al. Revised guidelines for the performance of peripheral vascular intervention. Catheter Cardiovasc Interv 1999; 46:21–23. 21. Sacks D, Becker GJ, Matalon TAS. Credentials for peripheral Angio- plasty: Comments on Society of Car- diac Angiography and Intervention Revisions. J Vasc Interv Radiol 2001; 12:277–280. 22. Higashida RT, Hopkins LN, Berenstein A, et al. Program requirements for Residency Fellowship Education in Neuroendovascular Surgery/Interven- tional Neuroradiology: A Special Re- port on Graduate Medical Education. AJNR 2000; 21:1153–1159. Connors et al • S319Volume 14 Number 9 Part 2