By Wes Isley

More than 780,000 strokes occur in the United States each year, according to the National Institute of Neurological Disorders and Stroke. Stroke causes more serious long-term disabilities than any other disease, and is the third leading cause of death in the country. The risk of having a stroke more than doubles each decade after age 55, and nearly three-quarters of all strokes occur in people over age 65. One-third are caused by atherosclerosis, or hardening of the arteries, a condition in which plaque collects on the walls of the carotid arteries located on either side of the neck and restricts blood flow to the brain.

To treat blocked neck arteries, physicians choose between a traditional carotid endarterectomy (CEA), in which a neck incision is made and plaque is removed from the artery, or the relatively new carotid artery stenting technique (CAS), in which a balloon angioplasty catheter is used to insert a stent (umbrella-like device) into the artery to hold it open and restore blood flow to the brain.

Both procedures have demonstrated success in preventing strokes, but until now, they had never been compared in a clinical trial to determine if one or the other was statistically more effective. The CREST study, which officially ends in 2011, has done just that.

Recently published results of the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) confirm what many vascular surgeons, interventionalists and stroke neurologists had suspected: Both CEA and CAS procedures are similar in safety and effectiveness. "Physicians now have validated data to say that if you have a serious carotid artery blockage, we can offer two procedures that are safe and durable for treatment," says Robert M. Schainfeld, DO, associate director of vascular medicine at Massachusetts General Hospital. "CREST provides us with more reassurance that both procedures are comparable in terms of their outcomes."

Good data by design
Sponsored by the University of Medicine and Dentistry, New Jersey in collaboration with the National Institute of Neurological Disorders and Stroke, CREST was launched in 2000, eventually enrolling 2,502 patients with significant carotid artery disease at 108 medical centers in the United States and nine in Canada. Eligible participants fell into two camps: symptomatic or asymptomatic. Symptomatic patients had to have experienced a transient ischemic attack (TIA) or mild stroke within the past six months. Asymptomatic patients were those who had not had a stroke or TIA within the past six months but who did have stenosis, or narrowing of a carotid artery, of 60 percent or more.

Once patients met eligibility criteria, they were randomly assigned to undergo either CAS or CEA. Participants were then monitored at regular intervals, most importantly at 30 days after the procedure and then at four years. The primary clinical endpoint, or goal, was to determine whether any patients suffered a post-procedural stroke, heart attack or death. Dr. Schainfeld, who was not a participating CREST clinician but who manages patient care as a vascular medicine specialist, says the design of the study should help settle heated debates in the medical community about whether either procedure—CEA or CAS—is more safe or effective. "Historically, the decision about which procedure to recommend has been up to the surgeon or cardiologist, but they don't necessarily have the same experience and training as a neurologist," says Dr. Schainfeld. "The design of CREST—prospective, multicenter, randomized, controlled—with the important caveat being that the clinical endpoints were blinded and adjudicated by independent stroke neurologists, helps level the playing field."

Another factor that strengthens the CREST data, says Dr. Schainfeld, is how thoroughly participating surgeons were screened. They had to demonstrate a large volume of successful CEA or CAS with low rates of complications or deaths, and each site was required to have a team consisting of a neurologist, an interventionalist, surgeon and a research coordinator.

Results and trends
CREST indicated that the overall safety and effectiveness of both procedures are statistically the same, with 7.2 percent of patients who received CAS experiencing a stroke, heart attack or death, and 6.8 percent of patients who received CEA having the same results. The study did reveal a few trends. Data showed that patients older than 70 years of age who received CAS had a greater incidence of stroke and faired better with CEA. In general, younger patients appeared to benefit more from CAS. This was due in part to the fact that patients receiving CEA had twice as many heart attacks post-procedure than those receiving CAS. Such trends, says Dr. Schainfeld, need to be examined further before definitive conclusions can be drawn about the risks of particular outcomes for either procedure.

Dr. Schainfeld says that the takeaway message from CREST for patients with carotid artery disease is "to keep an open mind about available treatment options and to get second or even multiple opinions, especially when the procedures are so comparable—and most imperative, whether they need a procedure done in the first place."