A common cause of stroke is the buildup of gooey, cholesterol-filled plaque inside arteries that nourish the brain. Clearing these blood vessels (the carotid arteries, which run up either side of the neck) can help prevent stroke. How best to do that has been hotly debated. Results from two trials presented at the International Stroke Conference, recently held in Los Angeles, call it a tie between the two contenders — an operation and a less-invasive procedure.
The operation, called carotid endarterectomy, involves opening the neck and the clogged artery and removing plaque. The procedure, called carotid angioplasty, involves inserting a thin tube tipped with a mesh-covered balloon into a blood vessel in the arm, maneuvering it into the clogged artery, and briefly opening the balloon. This squashes plaque to the side of the artery and expands the wire-mesh stent to hold open the artery.
In 2010, a trial called CREST showed that the two led to similar rates of stroke and death four years after treatment. Ten-year results from the trial, presented at the conference, showed much the same thing. Results of the recently completed Asymptomatic Carotid Trial (ACT), also presented there, demonstrated the equivalence of carotid surgery and angioplasty.
One thing missing from the new reports is the role of drug therapy as a possible alternative to, or addition to, surgery and angioplasty. Back in 2007, a landmark trial dubbed COURAGE showed that medical therapy was as good as angioplasty for treating clogged heart arteries. Could the same thing work for clogged neck arteries?
I talked with Dr. David E. Thaler, neurologist-in-chief at Tufts Medical Center and chairman of neurology at Tufts University School of Medicine, who was attending the stroke conference. Our conversation has been edited and condensed.
What do the new reports tell us about preventing stroke?
The results from the CREST follow-up and the new results from ACT lend support to the equivalence of surgery and angioplasty for people with severely narrowed carotid arteries, whether or not they are experiencing symptoms from the problem.
But there’s an important wrinkle I’d like to point out about the CREST results. The main outcome in that trial was a combination of stroke, heart attack, and death. There were more post-treatment strokes in the angioplasty plus stent group, while there were more post-treatment heart attacks in the surgery group. I think the emphasis should be on stroke, since people fear having a stroke more than a heart attack and because some of the heart attacks were measured biochemically, and had little or no effect on the patient.
Any other caveats?
Neither surgery nor angioplasty are risk-free procedures. They can cause the very thing they are trying to prevent — stroke — in a small percentage of patients. Other complications such as infection can also occur. That has to be weighed into the decision.
It’s also important to keep in mind that the physicians who took part in the trials were carefully selected. They did surgery or angioplasty often, and had low complication rates. We don’t know how well surgery and angioplasty work in real-world settings. Finding a physician who does carotid endarterectomy or carotid angioplasty at least several times a week is a good way to minimize the risk of complications.
Why wasn’t drug therapy included in the new trials?
When carotid artery surgery was first put to the test in the late 1970s and early 1980s, it was compared against drug therapy. Surgery was clearly superior for people who were experiencing symptoms such as transient ischemic attacks (TIAs, also called mini-strokes), and may have been better in people who were not experiencing symptoms.
Then angioplasty and stenting came along. When it came time to test that procedure head-to-head against surgery, “everyone knew” that surgery trumped drug therapy, so it was not included.
Is it time to take another look at drug therapy?
Drug therapy has changed a lot since the days of the early carotid surgery trials. Statins, which weren’t available then, help control atherosclerosis, the disease process that causes plaque to form. And we have other antiplatelet agents beside aspirin. These help prevent the formation of blood clots, which are the ultimate cause of most strokes.
The use of statins, antiplatelet agents, and other medications has helped reduce the occurrence of stroke among people with narrowed coronary arteries. A study I did with several colleagues showed that the stroke rate fell by almost 50 percent between 1978 and 2009 among patients with asymptomatic carotid artery disease who were treated with drug therapy alone.
The ACT investigators publicly raised the issue of drug therapy in their presentation at the International Stroke Conference and the accompanying article in the New England Journal of Medicine. More important, the National Institute of Neurological Disorders and Stroke is sponsoring CREST-2, which will directly compare carotid artery surgery, carotid stenting, and drug therapy.
Do you think drug therapy has a chance to succeed?
I think it will be close. If I had a patient with asymptomatic carotid artery disease, I would encourage him or her to join the trial. I think the existing data suggest that medical therapy has brought the stroke rate down to what surgery or angioplasty can do. It’s also possible that intervention plus modern drug therapy may be even better.