An Interview With Daniel Clair, MD
The Department Chair of Vascular Surgery at the Cleveland Clinic discusses the role of embolic protection devices and the potential impact of CMS's decision not to expand reimbursement for CAS.
What are your thoughts on CMS's decision not to expand reimbursement for carotid artery stenting (CAS)?
CAS and its success are not traced directly to tremendous reductions in morbidity for patients. Carotid endarterectomy (CEA) has proven over the years to be a relatively low-impact procedure, which requires hospitalization of only 1 night and a recovery time that varies from about 1 week to 10 days. The current impetus to continue CAS derives mainly from an attempt to treat patients who have poor or otherwise limited options for the treatment of carotid stenosis in an attempt to achieve stroke risk reduction. The most significant of these patient groups from a surgeon's standpoint are patients with carotid stenosis in the setting of anatomic restrictions on the performance of CEA. For this reason, I view CMS's recent decision to limit expansion for reimbursement of CAS as a significant blow to patient choice and patient safety. Although there are some who view this decision as a success, it is fairly clear to me and most surgeons who deal with these patients on a regular basis that this is a step backward in terms of the care for patients with carotid stenosis who have high-risk anatomic features.
Based on the available clinical data, what level of reimbursement would be appropriate?
It would appear, based on the currently available data, that high-risk patients, whether symptomatic or asymptomatic, should be reimbursed by CMS. Currently available registry data, which is either pending publication or recently published, suggest that combined stroke mortality rates are within the guidelines as suggested by the American Heart Association and therefore would imply benefit to these patients. This is particularly true for patients with anatomic high-risk criteria as reported by the recent SAPPHIRE group. In addition, recent presentations at the TCT meeting in October, including novel techniques for protection such as flow reversal and the FiberNet filter (Lumen Biomedical, Inc., Plymouth, MN) have documented extremely low stroke and death rates consistent with what would be necessary for stroke risk reduction in asymptomatic individuals.
If after the next set of data is published, CMS continues to maintain its current National Coverage Decision, what could this potentially mean to CAS further device development and study?
The decisions already reached by CMS regarding coverage of CAS have limited investment and development within the field of CAS. This latest decision to continue to restrict the coverage to individuals who are symptomatic and high risk has clearly led to a reconsideration by all of the major companies involved in peripheral intervention of their investment in carotid interventional device development. This also affects potential for "out of the box" ideas, which may come from small innovative companies, as manufacturers will find it more difficult to find investment dollars to fund additional development. It is my own impression that we would have seen more rapid development of technology to date had the initial coverage decision been broader.
Do you think carotid artery disease will increasingly be treated via CEA, marking an even more significant role for vascular surgeons in carotid treatment?
Currently, the predominant treatment for carotid stenosis remains CEA. This has been the primary form of treatment for at least the last 30 years. Because of the nature of this disease process and its association with other peripheral arterial disease processes along with the fact that surgeons have been intimately involved in the treatment of patients with carotid artery disease for the last 60 years, it is clear that surgeons will remain significant providers of care for patients with this disease process. The real issue this decision changes is the manner in which patients with this disease process will be treated. It is evident that most surgeons recognize that there are a significant number of patients with anatomic risk when performing CEA who benefit from carotid intervention.
Our goal as specialists in treating patients with peripheral vascular disease, and in particular carotid artery disease, is not to ensure that patients are cared for by one group of practitioners or another, but to ensure that the patients get the best method of care, the lowest risk from the procedure, and the highest likelihood of long-term success. Currently, for patients with recognized anatomic restrictions to performing CEA, the preferred procedure is clearly CAS. For vascular surgeons who perform not only CEA but also CAS and are looking for the best treatment method, this latest decision by CMS does not help our patients, it hurts them. It is my hope that with continued publication of results from current registries, CMS will gain enough information regarding the safety of the procedure to implement a coverage decision change for the benefit of these types of patients everywhere.
Based on what you have learned as principal investigator of the EMPiRE trial, what are the advantages of using a flow reversal embolic protection device?
The EMPiRE trial was another example of successful modification of technology and ideas to develop a safe device for treating patients with carotid stenosis. Nearly one third of the patients were symptomatic, and the data revealed outstanding results in a high-risk group. The flow reversal system itself provides several distinct advantages to current filtration systems used for protection. These include the ability to afford protection while crossing the lesion, some stabilization of the interventional system with inflation of the balloon in the common carotid artery, and the ability to treat lesions that might otherwise be deemed untreatable by interventional means. This potentially provides the platform by which patients with intraluminal thrombus, string sign, or "difficult to cross" lesions could be treated under the available flow reversal protection.
In addition, there is indirect evidence through several smaller studies that have been done utilizing this device that the incidence of diffusion-weighted magnetic resonance imaging abnormalities and transcranial Doppler high-intensity transient signals are dramatically reduced with this type of protection system. With the continued decrease in the profile of the device and ease of use of the device, I believe we will see increasing adoption of this as a method to provide cerebral protection for patients undergoing carotid stenting.
And the disadvantages?
The particular disadvantages to this device include its increased French size compared with other devices utilized to perform carotid intervention and the slightly increased time it takes to perform the procedure with flow reversal as opposed to a filtration system. For the interventionists who were involved in this trial, increasing numbers of procedures performed decreased the difference between time required for flow reversal and standard filtration systems; however, it takes time to learn how to use the device effectively to reduce the overall time of the procedure. Several additional points about these disadvantages include the fact that access-site complications were extremely low in the EMPiRE trial, and overall fluoroscopy and procedure times were lower than I would have expected given the fact that all of the investigators had little or no experience with this device ahead of time. I think this device makes particular intuitive sense to surgeons because of how we utilize flow reversal during CEA to provide safe return of flow to the internal carotid artery. I also believe that experienced interventionists can quickly learn how to use this device and take advantage of the specific protection enhancements this type of a system offers.
Having worked extensively with both of the primary types of CAS embolic protection devices, how would you decide which to use if each option were available and on your shelf (and reimbursable) when a CAS patient presented for treatment?
It is often difficult to predict which system any interventionist or I would use when performing a procedure. There are clearly situations that would provide an advantage for one protection system over another. Several specific examples I can think of that would make one system preferable to another include iliac occlusive disease, which would be likely a limitation of the current flow reversal system because of the size of the device. In this situation, a standard filtration system through a 6-F sheath with some of the currently available devices would reduce the risk of ischemia and damage to the iliac system. Additionally, previous stents placed in the arch vessel branches would pose difficulty for advancement of the flow reversal system; in fact, these are contraindications to using it.
On an alternate note, severe angulation or extremely tight stenosis within the proximal aspect of the internal carotid artery are situations in which marked advantage is offered by a flow reversal system. This device allows an individual to use the wire of his choosing in order to gain access across the lesion, and because only wire passage across the lesion is required (and not filtration system passage), treatment of the lesion with protection is much better afforded by a flow reversal system.
It is my impression that flow reversal in particular has the potential to reduce intraprocedural microembolic events, which are not well captured by gross neurologic exams or postprocedural CT scans but can be assessed by diffusion-weighted magnetic resonance imaging evaluation. Although I am not certain what long-term impact these have on patients, I consider them unfavorable events in terms of performing the procedure and for my own part would like to see them completely eliminated. One final point regarding carotid stenting concerns issues related to what I would like to see in terms of technologies from this point or what issues related to carotid stenting I think need to be solved from this point forward.
From the performance of the EMPiRE trial, as well as a number of other registries that have recorded data on outcomes of patients after CAS procedures, it is clear that the occurrence of embolic events, or, more precisely, symptomatic events, in the setting of CAS occur after performance of the procedure. Although it is distinctly possible that these events are delayed manifestations of intraprocedural embolic points, I believe it is unlikely that the vast majority are related to this, but rather they are related to embolic events, which occur from debris passing through interstices of the stent or around the ends of the stented segment following placement of the carotid stent. There is at least indirect evidence that closed stent systems may provide beneficial protection in reducing the incidence of periprocedural stroke events.
Although I am not sure closed stenting systems are the ultimate solution, as they limit the flexibility of the stent through the carotid segment, it is fairly clear that some attempt at better stent coverage of this region to reduce this postprocedural embolic potential will likely benefit patients. I would see this as the most likely opportunity to provide the best improvement in outcomes from CAS. Continued refinements and miniaturization of devices for intervention will move forward with any stenting and protection system as engineering techniques for these devices improve; however, the impact of postprocedural neurologic events needs to be addressed and corrected to achieve what in my estimation will ultimately be a stroke risk that is potentially even lower than that of CEA.
Competent surgeons performing CEA may particularly look at this statement as surgical heresy, convinced that CEA will never be surpassed by carotid intervention. Given the rate at which progress and risk reduction has occurred in CAS to date, I truly believe it is unlikely that CAS will not ultimately surpass CEA as a method of treatment. Because of the safety of CEA and CAS in general, it may be impossible to prove this hypothesis because of the number of patients required, but I believe within the next 5 years, we will have information that will validate the equivalence of CAS with CEA in all patients.