Carotid Stenting

In April of 2004, the FDA (Food and Drug Administration) approved carotid artery stenting. Unfortunately, here we are almost a year later, and the device is still not available and being used on a regular basis in clinical practice. What has happened? Permission was given to Cordis and Johnson & Johnson to market a carotid stent, on the basis of the landmark SAPPHIRE trial. The panel voted in favor of carotid artery stenting for high-risk and asymptomatic patients, as well as symptomatic patients; the vote was actually 6 to 5. The 5 votes against were by surgeons. On the basis of this decision, you start wondering, Is this a bad device or a bad technique? There are multiple players in this drama: the FDA, of course, and CMS (Centers for Medicare & Medicaid Services), who are the ones who actually have to pay for the procedure in the Medicare population. And then all the medical societies get involved; the Society of Vascular Surgery seems to be the loudest and the most adamant that this procedure should not be approved for clinical use. What this boils down to, ladies and gentleman, is a “turf battle.”

Carotid Endarterectomy: Warts and All

Approximately 180,000 surgical carotid endarterectomy procedures are performed annually in the United States. Interestingly enough, more than 70% of patients who undergo carotid endarterectomy are asymptomatic. Carotid endarterectomy is reimbursed for any symptomatic or asymptomatic patient who meets the following criteria: more than 50% stenosis for symptomatic, and more than 60% for asymptomatic patients. The surgeon performing carotid endarterectomy does not have to ask a cardiologist to agree with him, nor a neurologist to evaluate the patient before or after the procedure. Modern clinical practice and the validation of carotid endarterectomy evolved from 2 clinical trials that were performed in the United States in the early 1990s. The NASCET trial evaluated the benefit of carotid endarterectomy in symptomatic patients, and the ACAS trial was in asymptomatic patients; both showed that carotid endarterectomy was associated with a lower risk of stroke or death in comparison with medical therapy. Since then, carotid endarterectomy has become the “gold standard” for treatment of carotid artery disease. However, the results of the NASCET trial revealed that the death and stroke rate was 5.8%; other complications included cranial nerve palsy in 7.6%, neck wound hematoma in 5.5%, and wound infection in 3.4% of patients. The total perioperative morbidity and mortality rate was 26.2%. Please remember that this is a population of patients that would be currently considered “low-risk” for carotid artery stenting, because high-risk patients were excluded from the NASCET and ACAS trials.

Why should we consider recommending carotid stenting? Well, with carotid artery stenting, we can avoid general anesthesia; avoid a neck incision; and avoid the risks of postoperative infection, cranial nerve injuries, and other surgical complications. Carotid artery stenting is a shorter, less invasive procedure, with less blood loss, a shorter length of hospital stay, and a shorter recovery period. With carotid stenting, we can treat lesions that are difficult to treat with carotid endarterectomy, such as high cervical lesions and lesions that are below the clavicle. Most importantly, we can offer our patients a much less invasive alternative treatment with lower morbidity and mortality rates.

Since 2001, there have been major technological advances in carotid stenting. The advent of distal protection devices has significantly reduced the incidence of cerebral embolic events. The current stent delivery systems are specifically designed for use in the carotid arteries. They are lower in profile (5.0F and 5.5F) than previous devices, are made of nitinol, and are more flexible.

Recent Clinical Trials of Carotid Stenting

The SAPPHIRE trial was the 1st randomized, multicenter trial that compared stenting with distal protection to surgical carotid endarterectomy in 723 patients who were considered to be at high risk for surgery. The primary end-points were death, MI, and stroke. The stenting procedures were performed with a Precise Nitinol stent and the Angioguard distal protection device.

The follow-up results were analyzed after 6 months, 1 year, 2 years, and 3 years. These were truly high-risk patients. This study included patients who had undergone previous radical neck surgery, tracheostomy, radiation therapy, and even carotid endarterectomy. It included only patients with high-grade lesions, or those who had occlusion of the contralateral vessel. There was also a large group of patients with unstable angina and severe double- or triple-vessel coronary artery disease.

At 30 days, patients treated with carotid stenting had a significantly lower incidence of adverse clinical events in comparison with those who underwent carotid endarterectomy; this was true in both symptomatic and asymptomatic patients. The incidence of MI was also significantly lower in the carotid artery stenting group. None of the patients who received a carotid artery stent had cranial nerve injury, while approximately 5% of the surgical group did.

At 1 year, all clinical outcome parameters favored stenting in comparison with endarterectomy. Mortality was lower, there was a lower incidence of major ipsilateral stroke, a lower incidence of MI, and a lower incidence of the combined end-point of death, cerebrovascular accident, and MI. Target lesion revascularization was also significantly lower in the stenting group than in the carotid endarterectomy group. The data revealed that the benefits of carotid stenting were clearly durable.

The ARCHeR trial was also conducted in high-risk patients; however, this was not a randomized trial but a registry. The inclusion and exclusion criteria were similar to those for SAPPHIRE.

At 1 year, the incidence of major stroke and death was 2.5% in ARCHeR II (with distal protection) and 3.8% in ARCHeR I (without a protection device). Target lesion revascularization was also very low at 1 year, as it was in the SAPPHIRE trial.

There are several other trials—SECuRITY, BEACH, and CABERNET—that basically showed exactly the same results: the rate of major adverse cardiac events and the rate of complications were similar to those found in the SAPPHIRE and ARCHeR trials. In study after study, carotid stenting has been shown to be a safe, effective, and durable method of treatment for carotid artery disease.

CMS Puts on the Brakes

In December of 2004, CMS decreed to everyone's surprise that carotid artery stenting coverage would be approved (and paid for) only in high-risk symptomatic patients with 70% or more stenosis. These were not the inclusion criteria in the above-mentioned clinical trials. More importantly, asymptomatic patients are not covered for carotid stenting, but are free to undergo more expensive surgical procedures that will be paid for. In my opinion, something is really wrong with a system that allows this apparent bias in favor of surgery.

I believe that the turf battle that exists between surgical and nonsurgical specialists is the major culprit in the CMS decision. As long as financial issues are more important than the patient's well-being, this predicament will persist. Eventually, patients will demand to be treated with a less traumatic and an equally good or maybe better procedure, which is carotid artery stenting.

The Texas Heart Institute Experience

Since 1995, in collaboration with our very active surgical group at our institution, we have performed 412 carotid artery stenting procedures in 387 patients. Most of our patients have been high-risk patients enrolled in clinical trials, with severe comorbid conditions such as advanced age, severe coronary disease, heart failure, bilateral carotid disease, or contralateral carotid occlusion. Our technical success rate is 98%, and our incidence of complications is very comparable to that of the above-mentioned clinical trials. When we looked at our own data on unprotected versus protected carotid stenting (before 2002, cerebral protection devices were not available), the incidence of complications such as death, and major and minor cerebrovascular accident, was dramatically lower with the use of distal protection.

Credentialing

What if you decide you want to perform coronary artery stenting? What credentialing criteria will you need to meet? It is not entirely clear which path to follow, since there are multiple medical societies, the FDA, the manufacturers, and the individual institutions that make the decisions regarding credentialing.

The generally accepted criteria will likely be as follows: You will have to be a licensed interventionalist, regardless of whether you are a cardiologist, a radiologist, or a vascular surgeon. You will have to have credentials to perform peripheral procedures. You will have to have performed at least 25 cerebral angiograms. You will also have to complete a Web-based simulation education course. You will then have to participate in a carotid artery stenting live demonstration course. During this course, you will have to participate in a didactic session, observe from 4 to 6 demonstration cases, and perform 6 to 10 simulation cases on your own. And then you will have to perform 5 to 10 device-specific cases with a proctor at your institution.

Summary

From my point of view, carotid artery stenting, in 2005, is clearly here to stay. “Houston, the Eagle has landed.” The rest is up to you and me as we encourage our surgical colleagues and our various medical societies to embrace this safe, effective, and durable technology and make it available to the patients who will really benefit from it.