|
|
For other articles and previous issues click here. June 6, 2005 Carotid
Stenting — Developing a Less-Invasive Alternative to Endarterectomy The current preferred method of treating carotid artery disease is carotid endarterectomy, a surgical procedure usually done under general anesthesia in which surgeons cut into the neck artery to remove the blockage. An estimated 200,000 Americans undergo carotid endarterectomy each year. The surgery is performed when plaque and other fatty materials build up inside the carotid arteries, the two major arteries in the neck that deliver blood and oxygen to the brain. When narrowing occurs, or if the plaque breaks loose, patients are at risk for stroke. Stroke is the country’s third-leading cause of death behind heart disease and cancer, according to the American Heart Association. More than 730,000 people have new or recurrent strokes each year in the United States, and 280,000 of them die. Recently, studies have reported that a minimally invasive procedure can be as effective as surgery in high-risk patients. The minimally invasive procedure uses a combination of balloon angioplasty and a stent with a special filter to catch any emboli, or bits of plaque, that can break free during the procedure. It is the same technique used to clear coronary arteries blocked by heart disease, only carotid stents are somewhat larger and a distal protection device is used. Less Invasive Last August, the FDA approved the first carotid stenting system for use in the United States. The Acculink and Accunet system, manufactured by Guidant Corporation of Santa Clara, Calif., is approved for patients who have had symptoms of a stroke or whose carotid artery is at least 80% blocked and who are not good candidates for the surgical alternative. Acculink is used in conjunction with Accunet, an umbrellalike filter designed to trap particles of atherosclerotic plaque that might be released into the bloodstream during the procedure and may lead to stroke or other complications. Also last year, an FDA panel gave preliminary approval to the Cordis Carotid System, manufactured by Cordis Endovascular, a division of Cordis Corporation, a subsidiary of the New Jersey-based Johnson & Johnson (J&J). Like Guidant’s carotid system, the Cordis Carotid System has two components: a self-expanding stent and an emboli capture guidewire. Cordis Endovascular is working with the FDA to fulfill requirements for final marketing approval for its Cordis Precise and Cordis AngioGuard. (J&J/Cordis has since bought Guidant, but the Federal Trade Commission is requiring the companies to remain separate for now.) Several other companies are also working on carotid stenting devices, but they are further behind in development and the approval process, says Rodney D. Raabe, MD, director of interventional radiology at the Inland Vascular Institute in Spokane, Wash. Vascular stents are typically made of woven, laser-cut, or welded metal (nitinol) that permits the device to be compressed onto a catheter and delivered directly to the hardened artery. The stents are put in place to hold the artery open. Once the stent is in place and deployed, the previously placed emboli-protection device is collapsed and removed with the trapped particles inside. The cost of the materials used in carotid angioplasty and stenting is high, but the overall price of the procedure compares with surgery once you consider the cost of an operating room, anesthesia, and a longer hospital stay, according to the Radiological Society of North America (RSNA). Coverage Issue Study results have shown that carotid stenting benefits high-risk symptomatic and asymptomatic patients, says Katharine L. Krol, MD, director of vascular and interventional radiology at CorVasc MDs, PC, in Indianapolis. “The asymptomatic low-risk population is not quite as clear. [And so], there’s a lot of disagreement about this.” As with many minimally invasive procedures, a debate is raging over who should perform the procedure—interventional radiologists, vascular surgeons, cardiologists, neurosurgeons, neuroradiologists, or some combination of specialists. In March, the CMS issued its final decision on coverage for carotid stenting outside of ongoing clinical trials. Under the ruling, coverage is limited to symptomatic, high-risk patients with 70% or greater carotid stenosis. No asymptomatic patients and no “normal-risk” patients are covered. High-risk patients are defined as those with previous endarterectomy, severe heart disease, severe lung disease, previous radiation therapy, and lesions above the lower jaw or collarbone. Symptomatic patients are those who have had a stroke, a transient ischemic attack, or transient blindness in one eye. Asymptomatic patients are detected by cervical or neck bruit—a sound heard with a stethoscope—or other screening methods. Most clinical trials initiated since 2001 have involved high-risk patients, says Mark Wholey, MD, MS, FACR, of the University of Pittsburgh Medical Center-Shadyside Hospital and chairman of the Pittsburgh Vascular Institute. The data from those trials are impressive, he says. They show that carotid artery angioplasty and stenting has similar safety and efficacy as surgical carotid endarterectomy in patients at high risk for stroke. “Stenting proved superior to endarterectomy when you include the end points of the studies, which were stroke, myocardial infarction, and death,” Wholey says. A major study, Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE), enrolled 747 patients at 29 treatment centers in the United States. First presented at the Transcatheter Cardiovascular Therapeutics meeting in 2003, it found that the 30-day adverse rate—death, stroke, or myocardial infarction—was 50% lower with stenting than with surgery. The procedure continued to show excellent results after one year. The SAPPHIRE study results have since been supported by several others, including Acculink for Revascularization of Carotids in High-Risk Patients (ARCHeR), says Wholey, a principal ARCHeR trial investigator. However, Wholey says, high-risk patients are only a small fraction of those who undergo carotid endarterectomy. “Further trials are needed for the low- or moderate-risk patient because that issue is not yet answered,” he says. Patient Choice However, Raabe says, when patients are told they can have surgery that involves a large incision, a drain coming out of their neck, and a hospital stay of several days, or stenting, which involves a small incision in the groin, and an overnight stay at most, they likely will choose stenting. “They are going to say, ‘Geez, I can get a stent and be in and out of the hospital in a day? I want that.’” The patient demand for stenting may help push its physician acceptance faster. Thanks largely to the Internet, Raabe says more patients are researching their symptoms and conditions and coming into their doctor’s office adamant about the treatment they prefer. While Krol agrees with the CMS’s draft coverage decision, she says it’s often hard to adhere strictly to the research in practice. “My dilemma is when I’ve got a patient and I really think stenting would be the better option for them, and they’re not going to be covered,” she says. Looking at the data is different from looking at a patient, she says. “When you have a patient sitting in your office who has just been told he has a carotid artery that needs to be fixed, and that surgery is [his] only option—Medicare says no to stenting, a lesser risk procedure—it’s hard to get [him] to understand.” Wholey says it would be unconscionable to send a patient with a high-grade stenosis of the dominant hemisphere carotid artery home “and presume they’re best managed medically when you know eventually that vessel is going to erupt. That’s like sending them home with a stroke warrant.” Wholey believes the CMS’s policy is too restrictive and needs to be restructured. Ongoing Research “I’m fortunate that I have several IDEs, so I can continue to treat those patients in a way that allows us to collect the data and make a case for whether or not it’s appropriate treatment,” she says. In September, Cordis Endovascular researchers enrolled the first patient in a surveillance study that will provide ongoing data about the carotid stenting procedure. The surveillance study will enroll patients at 112 sites in the United States. In October, Guidant began enrolling patients in its FDA-required postmarket study CAPTURE (Carotid Acculink/Accunet Post Approval Trial to Uncover Rare Events). The study plans to follow more than 1,500 patients from multiple sites. Two reasons why the CMS has been cautious about approving the procedure are concerns about the training and the experience of the physicians performing it. “Carotid endarterectomy is a pretty darn good procedure and the results are pretty darn good,” Raabe says. “You have to have the talent and skills to do carotid stenting to match and/or beat the surgical results. So if you have beginners out there, you could end up causing the public more harm than good.” Several types of specialists, including vascular surgeons, cardiologists, interventional radiologists, and neuroradiologists, have at least part of the medical knowledge, skills, and training involved in performing the procedure, which Raabe notes involves the neurological assessment as well as interventional vascular techniques. Vascular surgeons have the medical knowledge and training to decide who needs to have it done. But as a group, they don’t have the technical skills because they are surgeons, and carotid stenting requires more interventional skills, he says. Cardiologists have good technical procedure skills but aren’t involved in working with the neuroanatomy or blood vessels in this area or catheterizing them, he says. “Then you have interventional radiologists and neuroradiologists who have very good technical skills and can catheterize and treat these arteries, but who tend to have less patient management skills before and after the procedure.” What the FDA and the CMS are trying to do is “make sure everybody will come out with good training skills both in taking care of the patient and the technical skills of knowing who to do and who not to do,” Raabe says. Shared Turf Wholey, who has placed nearly 1,000 carotid stents, sees no need for a turf battle over the procedure. “It could be an interventional radiologist, an interventional neuroradiologist, or a very experienced cardiologist, or a very experienced vascular surgeon, as long as you have the experience and the background and the ability to take care of strokes and can do all these interventions,” he says. In fact, he says, the best approach may be a team from the different specialties. “A combination of that team is just ideal for the patient.” The manufacturers are also being careful about who uses their carotid stenting systems. For example, Guidant sells devices only to physicians with the appropriate training and prerequisite experience for performing carotid interventions. Also, the company has worked closely with the FDA, medical societies, and leading practitioners to develop targeted training programs in the use of its Acculink/Accunet Systems for physicians. Looking Ahead “I understand that CMS doesn’t want physicians to go wild with carotid stenting because when that happens, you see a much higher stroke rate than we’ve seen in carefully monitored trials,” Wholey says. “I think when we show the data is equal to or better than surgery, we’ll see more asymptomatic patients. Most medical societies, especially those involved in vascular studies, feel the CMS statement was unreasonably restrictive and needs to be restated to include asymptomatic high-risk patients. It was a very vocal minority who accepted the draft statement.” Raabe believes that in five or so years, when all the regulatory issues are sorted out and the study data are in, 80% of carotid blockage patients requiring treatment beyond medication will undergo stenting and 20% will have an endarterectomy. “Carotid stenting will be very easy for patients,” he says. “You’ll have a very low rate of problems with the procedure. Most patients will come in and out the same day or a short overnight stay and the patients that will undergo surgery will have inappropriate anatomy or will have something from an anatomical point of view that it would be better for them to have surgery vs. stenting.” — Beth W. Orenstein of Northampton, Pa., is a freelance medical writer. |
 |
 |