Hypertension and Stroke Special Report
Stents for the Carotid Arteries
Johns Hopkins reports on the risks and benefits of carotid artery stents versus traditional carotid endarterectomy.
Five years ago, the only way to treat a carotid artery narrowed by the buildup of plaque was to perform a surgical procedure called carotid endarterectomy. Today, however, you and your doctor have another option in the fight against a stroke -- a less invasive procedure that involves the use of carotid artery stents.
The carotid arteries are the blood vessels that run along either side of the neck and supply the brain with blood. When these arteries become significantly blocked by plaque, a carotid artery endarterectomy is sometimes performed. In this procedure, surgeons make an incision in the neck, open up the affected carotid artery, and remove the plaque that is interfering with the flow of blood to the brain. It can be a lifesaving procedure, but like all surgeries, it carries serious risks.
In August 2004, the U.S. Food and Drug Administration (FDA) approved the use of the first carotid stent to reduce the risk of strokes. The device and more recently approved ones are for people who have had stroke symptoms or whose carotid artery is at least 80% blocked.
A stent is a small wire mesh tube. A vascular surgeon maneuvers the stent to the site of the blockage, using a catheter that is inserted in an incision in the groin and threaded through the cardiovascular system to the main neck artery (a procedure called angioplasty). Once the stent is at the blockage site, a balloon is inflated to widen the artery, and the stent is permanently put in place to keep the artery open.
The FDA approved the first carotid stent based on the findings of clinical trials that involved 581 patients at high risk for a stroke. In these individuals, the stent successfully opened narrowed arteries 92% of the time. In addition, there was a relatively low risk of complications; about 10% of patients who received the carotid stent experienced a stroke, heart attack, or death within 30 days of the procedure, compared with the 15% complication rate typically associated with carotid endarterectomy.
Other advantages of the carotid artery stent include that it requires only local anesthesia (general anesthesia is used for carotid endarterectomy) and the recovery time is much shorter -- only a one-night stay in the hospital, compared with about two to three days in the hospital after carotid endarterectomy.
More research on the use of the carotid artery stent
Since the first approval of a carotid artery stent, a major study published in The New England Journal of Medicine weighed in on the benefits and risks of stents in patients with 5080% blockage of their carotid arteries. The patients enrolled in the study also had at least one other risk factor for a stroke (such as diabetes or heart disease), and were divided into two groups -- one that received a carotid-artery stent and the other that underwent traditional carotid endarterectomy.
One year later, the raw data showed that the patients who underwent carotid stenting had a lower number of strokes or heart attacks. When the data were analyzed further, however, the differences between the groups were clinically insignificant. Still, the need to repeat the procedure because of restenosis (renarrowing of the carotid artery) occurred less often in those receiving stents. The researchers concluded that carotid stenting is not inferior to carotid endarterectomy.
Other studies have reached similar conclusions. For example, researchers in Italy conducted a long-term trial of 180 patients with blockages in their carotid arteries. Some of the patients received carotid stents, while others underwent traditional carotid endarterectomy. Both of these approaches were equally effective in reducing blockages of the carotid arteries, and three years after the procedures, both groups had similar rates of neurological complications (about 3%, including two minor strokes and one major stroke in the stent group). Both groups also had a similar incidence of restenosis (4%).
Despite these positive findings, some doctors are taking a wait-and-see attitude toward carotid artery stents because there are much more data on the successes and risks associated with carotid endarterectomy. As a result, Johns Hopkins and most other academic medical centers still consider a carotid endarterectomy to be the best option.
At Hopkins, carotid stenting is typically performed only in those who are unable to undergo a carotid endarterectomy or have blockages in the carotid artery that have recurred after theyve already undergone carotid endarterectomy; in both cases, these blockages must be causing stroke symptoms, either TIAs or full-blown strokes.
Even if you meet these criteria, you may not be a good candidate for carotid artery stenting. According to the Society of Vascular Surgery, stenting may not be the optimal choice to reduce stroke risk if you have an irregular heart rhythm, bleeding in the brain within the last two months, or complete obstruction of the carotid artery. You may also have an increased likelihood of complications during carotid stenting if you have high blood pressure, significant bends or other complex anatomical features of the carotid arteries, or allergies to contrast dyes (which are used to assist in the imaging of the arteries during the procedure).
Many lingering questions about carotid stenting will hopefully be answered by a major randomized study, called the Carotid Revascularization Endarterectomy vs. Stenting Trial (CREST), which is supported by the National Institute of Neurological Disorders and Stroke. Conducted at 70 medical centers in the United States and Canada, and involving more than 2,500 patients, it will compare carotid stenting vs. endarterectomy. Its results are not expected until 2012.
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Posted in Hypertension and Stroke on February 20, 2007