Carotid Artery Surgery May Prevent Stroke

May 6, 2004 -- Preventive carotid artery surgery can reduce stroke risk by half in people with narrowing of the arteries but no symptoms. However, the surgeon must have a sterling track record, cautions one expert.

The study and commentary appear in this week's issue of The Lancet.

Carotid surgery has become the treatment of choice for patients who have had a mild stroke or transient mini-stroke that occurs when the neck arteries, called carotid arteries, become narrowed by 70% or more from blockages. During surgery, doctors remove the blockages in the neck artery and implant a mesh stent to keep the artery open.

But in recent years, surgeons have debated whether people with substantial neck artery narrowing but no stroke or mini-stroke should have the surgery as a preventive measure. Carotid artery surgery itself carries a risk of causing a stroke. Is that risk worth it for patients with no symptoms?

These are the issues addressed by lead researcher Allison Halliday, MD, a vascular surgeon with St. George's Medical School in London.

Two recent U.S. studies showed promising results for reducing mini- and non-disabling strokes in this high-risk group. But there was no decrease in the numbers of patients suffering fatal or disabling strokes, she notes.

Surgery vs. Watchful Waiting

To help clarify the issue, Halliday and her colleagues have been following the progress of 3,100 patients in 30 countries for the past five years. All the patients had at least 60% narrowing of one or both carotid arteries. None of the patients had any other life-threatening condition that would bring added risk to the surgery.

Half the patients had immediate carotid artery surgery. The other patients deferred surgery and continued their drug treatments as usual -- "watchful waiting" -- until they showed signs of worsening, and then surgery was done.

Researchers found:

• 3% of those receiving immediate surgery had a stroke or died within 30 days of surgery.

• Among those who deferred surgery, 20% needed surgery within five years and 4% had a stroke or died within 30 days of the surgery.

• Preventive surgery reduced the number of strokes due to blockages or mini-strokes: 3% of the surgery group and 10% of the watchful-waiting group had mini-strokes.

"The reduction of about four-fifths in carotid [artery-related] stroke is so extreme that it can be reasonably" advised for patients who have severe carotid artery blockages, writes Halliday.

Although wider use of cholesterol-lowering statin drugs will somewhat reduce the overall risk of stroke, the remaining risk "should be avoidable by successful surgery," she writes. Unsuccessful surgery, however, can do much harm if it's done by an inexperienced or unskilled surgeon.

Good use of drug therapy should lower any remaining risks -- both after surgery and if surgery is not performed, she writes.

Carotid surgery is best for patients under age 74, writes Halliday. Half of all older patients die within five years from unrelated causes. She will continue following patients in her study for a full 10 years.