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HEALTH SENSE

Carotid stents get better, but proof they work is scant

Stents, long famous for their success in propping open clogged arteries in the heart, are now being used in neck arteries in an effort to reduce strokes.

Technical advances have made the stents safer to insert in neck arteries, and some experts now fear that doctors may adopt the procedure -- and patients may clamor for it -- before there is sufficient research to support it.

With carotid stenting, doctors insert a mesh device into a clogged carotid artery in the neck to keep blood flowing to the brain. The stents can be placed in the carotid arteries without general anesthesia.

''The procedure is less invasive and recovery is faster than with endarterectomy," the traditional surgical approach to fixing narrowed arteries, said Dr. Marc Mayberg, executive director of the Seattle Neuroscience Institute, a research center. But he said carotid stenting ''may be overapplied in patients who actually don't need it, who don't need any treatment at all, or who would do well on medications alone."

So far, he said, ''there is little scientific data yet to show that stents are an effective way to prevent strokes, while there is such data for endarterectomy," which involves cutting open the arteries and scraping out fatty debris. Every year, roughly 150,000 Americans undergo this procedure.

The new procedure does have a growing number of fans.

Carotid stenting is clearly ''the coming thing," said Dr. Barry T. Katzen, medical director of the Baptist Cardiac and Vascular Institute in Miami. ''We are very excited about this technology."

Although carotid stenting has been around since the early 1990s, it is taking off now because engineers have devised a way to catch debris that can be knocked off artery walls during insertion of the stent -- and could otherwise travel to the brain and cause strokes.

''We now have equipment that is much smaller, much more elegant," making the procedure easier and safer, said Dr. Piotr Sobieszczyk, a cardiologist at Brigham and Women's Hospital. ''In the future this may well be the preferred way of treating carotid artery blockages."

The addition of the debris filter has been ''crucial to the rapid development of this procedure," said Sobieszczyk.

Carotid stenting got another boost last year when Medicare agreed to pay for the procedure in certain patients.

Despite its promise, though, stenting will probably not be the first choice for many people at risk of stroke.

In 2003, the latest year for which statistics are available, more than 700,000 Americans had strokes and nearly 158,000 were killed by them, according to the American Heart Association. High blood pressure, smoking, and clogged carotid arteries are all risk factors for strokes. Carotid stents are designed to address the small percentage of strokes that are caused by a buildup of plaque in the carotid arteries.

While there are not as much data on stenting as on surgery to prevent strokes, a major study called SAPPHIRE, published in 2004, did show that carotid stents were just as effective at reducing strokes in high-risk patients as endarterectomy and were linked to fewer heart attacks during the procedure. After three years, stroke risk in both groups about 5 percent, said Katzen, one of the study's authors.

There are risks to both procedures. The major risks of endarterectomy include infection and injury to nerves in the neck, plus bleeding and heart rhythm disturbances; the major risks of stenting include bleeding from the artery in the groin through which the stent is threaded, and heart rhythm disturbances.

On the plus side, there is preliminary evidence that carotid stenting may improve cognitive function, said Dr. Rod Raabe, an interventional radiologist at the Sacred Heart Medical Center in Spokane, Wash. A study Raabe presented in March at the annual meeting of the Society of Interventional Radiology showed a statistically significant improvement in memory and other cognitive skills after stenting, even in patients who had not had strokes.

But the big outstanding question is this: Should stenting be used for people at moderate risk of stroke who have no overt symptoms, like transient ischemic attacks, also known as mini-strokes. That issue is now being addressed in a study called CREST funded by the National Institutes of Health, which is still open to new patients.

Until that study is finished, the prudent course, if you're are at risk for stroke -- because of high blood pressure, being a smoker, having clogged carotid arteries, or other risk factors -- is to talk with your doctor and try medications first to reduce your risk. If these don't work and you need something more invasive to keep your carotid arteries open, ask your doctor about endarterectomy and stents and how much training your doctor has had in these procedures. And don't be afraid to get a second opinion.

Judy Foreman is a freelance columnist who can be contacted at foreman@globe.com.

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