It was the December issue 2004 of VDM when we last editorialized about the status of carotid artery stenting (CAS) in these pages. And quite a bit has happened since! Taking into account the continuing strength and impact of carotid interventional developments, it seemed appropriate and timely to revisit the “CAS story” and provide a current update:
1. FDA Approval: two CAS systems (stent/embolic protection filter) have received full approval and have been released for commercialization. Interestingly, they both came to rest within the domain of one single company (!) — the result of corporate transitions and acquisitions. The label indication is high-risk (for endarterectomy) only, both symptomatic (>50% stenoses) and asymptomatic (>80% lesions).
2. The reimbursement decision by CMS was a bit narrower than the FDA approval as asymptomatic patients were excluded altogether.
3. As predicted in the VDM 2004 editorial, carotid filters have now been “detached” from the CAS systems and — appropriately — reclassified as Class 2 devices (non-implants), thereby enabling regulatory approval through a 510k pathway. And so far, one such filter has been approved for carotid use within that framework: the Spider filter by ev3.
4. Technology-driven issues:
a. Aspects surrounding carotid stent design have recently received much attention, with some leading investigators questioning whether open-cell devices provide enough scaffolding and lesion exclusion. Preventing embolization, both immediate and delayed, and adequate lesion scaffolding and coverage are increasingly regarded as more important than flexibility and conformity. At a minimum, these evolutions will generate a demand for more related information, and a refocusing on closed-cell stent designs – and the carotid Wallstent.
b. Proximal occlusion and flow reversal systems continue to be unavailable in the United States, but we all agree that they will likely find an important place in our CAS armamentarium in the years to come. Testing of such systems in properly designed and carefully conducted clinical trials is eagerly awaited.
5. Enthusiasm for CAS continues largely unabated, but a number of important qualifications have emerged in the recent past:
a. There is rapidly mounting evidence that carotid stenting is probably less safe than carotid endarterectomy (CEA) for octogenarians.
b. There continues to be little if any evidence that CAS should be offered to non-high-risk patients — outside the context of a well-controlled trial. Several large clinical studies, both randomized and non-randomized, are presently commencing or in the planning stage. Such data will be several years in the making.
c. The concept that anatomical suitability of the aortic arch and the common and internal carotid arteries is the most important determinant of success and potential CAS-related complications has been reaffirmed. And operator’s experience is also viewed as extremely important, but there are emerging data (from post-marketing surveillance studies) showing that the potential adverse impact of inexperience on outcome can be minimized through proper education and training — proctoring included.
So, what does the future hold for CEA? One thing for sure: surgical treatment of carotid artery stenosis is not going away any time soon! In fact, we find ourselves doing (proportionally) more CEA today than 2 years ago. CAS is clearly emerging as a worthy competitor to CEA, but one for which we still lack clearly defined indications. Personally, I would look at stenting as an option that will likely be used increasingly on patients who are at “low-risk for CAS” – as opposed to the “time-honored” strategy of offering the new therapy to patients at high-risk for CEA, often resulting in the selection of some of the most difficult patients for percutaneous intervention.
In the end, CAS developments continue to be pre-eminent in the vascular world. It has emerged — undeniably — as an important new treatment option for many patients. However, the boundless enthusiasm of the early days is (appropriately) beginning to be tempered by two powerful forces: data and reality! Stay tuned, and look for further VDM updates on this most important vascular topic within the next several months. |
