Veith's Viewpoint: Is Carotid Stenting Really 'Disruptive Technology'?

Carotid balloon angioplasty was first performed in 1980, and a stent was first used in 1989 to treat an intimal flap after angioplasty. Since then, there has been increasing interest in carotid angioplasty and stenting or CAS, as interventional specialists who had little previous interest in treating carotid bifurcation arteriosclerosis rushed to apply their endovascular skills and tools in this new area of opportunity for them.

The technique for performing CAS was perfected largely by interventional cardiologists and a few interventional radiologists. Industry contributed technical improvements with lower profile systems, better stents, and a variety of embolic protection devices. Presentations, articles, registries, and courses proliferated dramatically.

It certainly appeared that CAS was a "disruptive technology" that would replace the previous preferred surgical treatment, carotid endarterectomy (CEA). The appearance of this disruptive technology was potentiated by low adverse event rates observed when CAS was performed extensively in registries comprising asymptomatic patients (up to 90% in some registries).

Based on these registry results, in the early 2000s some CAS enthusiasts, particularly in the interventional cardiology community, were claiming vociferously that carotid surgery was obsolete and that CAS was already equal to or better than CEA.

All sorts of specialists rushed to learn how to perform the new technology before it was too late. These specialists included not only the colleagues of the many interventional cardiologists and the few interventional radiologists who had pushed CAS from the beginning but also interventional neurologists. They all saw the opportunity to earn procedural dollars.

Even vascular and neurologic surgeons crowded courses in an effort to get on the rapidly moving train. CAS truly appeared to be a disruptive and better technology that could blow away an old inferior one.

Then around 2006, some disturbing cracks began to appear in the facade of the new technology. Unacceptably high adverse event rates were observed when CAS was performed in octogenarians, particularly those who were symptomatic. Then high adverse event rates for CAS performed in symptomatic patients were reported in several randomized prospective trials. In one of these, the EVA 3S trial in France, CAS had a significantly higher stroke and death rate than did CEA. Although some criticisms of this study have been made by CAS enthusiasts, none appears to be crucial. Moreover, meta-analyses of trials suggest that CEA is safer than CAS, particularly in symptomatic patients, and two population-based studies in the United States show that CAS has significantly higher stroke and death rates than CEA.

Since the appearance of these data, many of the original CAS enthusiasts have recently expressed a note of caution and suggest the need for CAS operators to select patients more carefully, avoiding those with imperfect anatomy or ugly high-grade calcified lesions.

In light of these developments, it is fair to pose the question: Is CAS really a disruptive technology? If one defines a disruptive technology as one that will largely replace the existing treatment, the answer has to be no.

If one defines a disruptive technology as one that shakes up and changes the existing treatment landscape, the answer has to be yes. Some patients clearly will be better treated with CAS; some will be better treated with CEA. And some, perhaps even most asymptomatic patients with carotid bifurcation lesions will be best treated with improved medical treatment using optimal doses of statins, ?-blockers, and antiplatelet agents and with diabetic control.

While it will be at least several years until the exact proportions of carotid patients who are best treated by these three modalities are known, CAS already is disruptive since it will force us to look at these questions and certainly will have some role to play. CAS probably will not be disruptive in the sense that it will never replace the other treatments completely or even almost completely since the other treatments are effective and low risk.

CAS can never be as disruptive a technology as endovascular aneurysm repair will be to open AAA repair or thoracic endovascular aortic repair will be to open thoracic aneurysm repair. Therefore, CAS will never be as disruptive as its enthusiasts might have hoped it would be. It will, however, have a positive impact on the treatment of carotid artery disease. The nature and extent of that impact remain to be determined.