Studies support anti-stroke surgery

ON CALL

January 10, 1995|By Dr. Simeon Margolis | Dr. Simeon Margolis,Special to The Sun

Q: My doctor has recommended surgery to remove an obstruction in an artery in my neck. He tells me that such surgery will lessen the danger of a stroke. I have never had any symptoms suggestive of a stroke and am reluctant to undergo such surgery. How good is the evidence that surgery to neck arteries prevents strokes?

A: Much controversy has surrounded the introduction in 1954 of an operation, known as carotid endarterectomy, to reduce the risk of a stroke. In this operation, an opening is made in one of the carotid arteries, the arteries in both sides of the neck that are major suppliers of blood to the brain. Doctors then remove atherosclerotic plaque obstructing the blood flow through the vessel. Over the past three years, the results of two large studies have finally clarified the potential benefits of this type of surgery.

The first study, published in 1991, included 1,212 patients with a prior stroke or a history of transient ischemic attacks (short-lived episodes such as loss of vision, difficulty speaking or limb weakness resulting from poor blood supply to the brain). All were randomly assigned to medical treatment or carotid endarterectomy. In those whose carotid artery was narrowed by 70 percent or more, 26 percent of those treated medically had a stroke over the next two years compared with only 9 percent of those who had surgery. (The benefits of carotid endarterectomy in patients with lesser degrees of arterial obstruction are still uncertain.)

In September 1994, the National Institutes of Health released a preliminary report of a seven-year comparison of medical vs. surgical treatment in patients with a narrowed carotid artery but no prior symptoms of stroke or transient ischemic attacks. Such narrowings can be detected with a stethoscope placed over the neck which picks up a murmur, or swishing sound, over the artery, then confirmed by an ultrasound study or an X-ray after the injection of a contrast material into the artery.

Investigators at 39 places in the United States and Canada studied 1,662 men and women between the ages of 40 and 79 who had a 60 percent or greater narrowing of one carotid artery. Carotid endarterectomy was performed in half; the rest were treated medically. The risk of stroke over a five-year period was significantly lower in those treated surgically (4.8 percent) compared with 10.6 percent in those treated medically. The reduction in risk after carotid endarterectomy was much greater in men than in women.

The results of these two studies clearly show a reduction in the number of strokes after endarterectomy for 60 percent to 70 percent obstructions of a carotid artery in the presence or absence of prior symptoms, especially in men in the latter case.

In making a decision, you should ask the extent of the narrowing, because the reduction in the number of strokes was greatest in those with the greatest degree of obstruction. Keep in mind that

there are more strokes, and deaths, in the immediate post-operative period as the result of the surgery. You should insist on an experienced vascular surgeon and ask for the results of his or her operations for carotid endarterectomy. The cost of the operation is about $15,000.

Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.

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