Opening a blocked heart artery with a balloon and then propping it open with a wire-mesh stent has become a near-equal partner with bypass surgery for restoring blood flow to the heart. Although coronary angioplasty plus stenting isn't quite as durable as bypass surgery, it is much easier on the body, since it doesn't require opening the chest. Giving up a tiny bit of effectiveness for a much shorter recovery is an excellent trade-off for some people.
The situation is different in the carotid arteries, which convey oxygen-rich blood to the brain. In that territory, carotid angioplasty plus stenting (CAS) hasn't quite proved itself to be the equal of endarterectomy, an operation to clean out a clogged carotid artery. Results from one long-awaited clinical trial showed that CAS is nearly as safe and effective as carotid endarterectomy when done by an expert, while results from a second trial indicate that surgery is still the best bet for most people.
An often-silent disease
The right and left carotid arteries branch off the aorta soon after it emerges from the heart and run up to the brain along either side of the neck. These vitally important arteries are prone to atherosclerosis, the damaging process that clogs arteries in the heart, kidneys, legs, and elsewhere.
A buildup of plaque in the carotids usually goes unnoticed. Sometimes it is discovered when a doctor hears "bruits" (BROO-ee) through a stethoscope in one or both carotid arteries. These soft, whooshing sounds are caused by turbulence as blood tumbles through a narrowing in a carotid artery. Clogged carotids are sometimes found during ultrasound exams of the neck and head. For most people, though, the first sign of trouble is a transient ischemic attack or a stroke.
Just as a heart attack is the big worry with cholesterol-clogged coronary arteries, brain attack (stroke) is the main hazard of plaque-narrowed carotid arteries. Plaque in a carotid artery can cause a stroke by restricting blood flow to part of the brain, or by breaking loose and completely blocking a smaller vessel in the brain.
Clearing a carotid artery
Endarterectomy removes fatty plaque through an incision in the neck. Angioplasty plus stenting opens the narrowing from the inside with a balloon and leaves behind a stent to hold the artery open.
Opening a clogged carotid
There are two main ways to open a narrowed carotid artery.
Endarterectomy involves physically removing plaque from inside the carotid artery. A surgeon makes an incision in the neck to expose the artery, clamps the artery, then opens it lengthwise in the region of the narrowing. After scraping the fatty plaque out of the artery, the surgeon enlarges the artery with a diamond-shaped patch, stitches the artery together, then closes the skin of the neck.
Carotid angioplasty begins with a small incision into the femoral artery in the groin. A thin tube called a catheter is gently pushed into the artery and maneuvered up through the aorta into the narrowing in the carotid artery. An umbrella-shaped filter is placed beyond the narrowing to catch any dislodged plaque or debris. Once everything is in place, a balloon on the catheter is inflated, mashing the plaque into the artery wall and expanding a stent. The balloon is deflated; the catheter and filter are removed, leaving the stent in place to hold the artery open; and the incision in the groin is closed.
Downside of treatment
The main goal of carotid endarterectomy or angioplasty is to prevent a stroke from happening in the future. Both do this quite well. What makes deciding which procedure to have — or whether to have one at all — difficult is that both endarterectomy and angioplasty sometimes cause a stroke, the very problem they are trying to prevent, or, even worse, death.
Most people — upward of 90% — sail through CAS or carotid endarterectomy without a hitch. Nationally, about five people in 100 have a stroke or die as a result of a procedure to clear a clogged carotid artery. The rate is much lower when the procedure is performed by a doctor who has done it many times.
In the first report from the Carotid Revascularization versus Stenting Trial (CREST), carotid surgery and CAS were, on the surface, equally safe and effective. But when the investigators drilled down into the data, some important differences emerged. Stroke was more common after CAS (4.1%) than after surgery (2.3%), while heart attack was more common after surgery (2.3%) than after CAS (1.1%). However, most of the heart attacks were mild, while most of the strokes caused some disability and reduced quality of life. As seen in other trials, individuals over age 69 did better with surgery than with CAS. The results were presented in February 2010 at an American Stroke Association conference in San Antonio.
Interim results from the ongoing International Carotid Stenting Study (ICSS) seem to tell a different story. They showed a higher rate of stroke, heart attack, or death with CAS (8.5%) than with surgery (5.2%) within 120 days of the procedure (The Lancet, March 20, 2010).
Clearer picture for CAS
To clarify these results, we polled the chiefs of vascular and endovascular surgery at Harvard Medical School's three main teaching hospitals: Dr. Michael Belkin of Brigham and Women's Hospital, Dr. Richard A. Cambria of Massachusetts General Hospital, and Dr. Frank Pomposelli of Beth Israel Deaconess Medical Center.
All agreed that the differences between CAS and surgery are getting smaller due to the improvements in CAS since it was first introduced. In expert hands, they say that CAS can be a viable alternative to carotid endarterectomy. A big reason for the differences in results between the two trials is that doctors had to demonstrate considerably more expertise to participate in CREST than in ICSS. That means the ICSS findings likely reflect what will happen with CAS when done by doctors of varying skill.
Differences remain
When carotid angioplasty was first developed, doctors hoped it would be just as effective as carotid endarterectomy but easier on the body. That hasn't panned out. Both procedures take an hour or two to perform, and both require only a one-night stay in the hospital. Full recovery is a bit quicker from CAS than from endarterectomy, but this difference isn't nearly as big as it is between coronary angioplasty and bypass surgery.
On the safety side, carotid endarterectomy has set a high bar. As operations go, it is quite safe, with rates of stroke, heart attack, or death as low as 1% to 2% in centers where the operation is performed often (at least once a week) by experienced teams. CAS comes close to this when done in centers of excellence, as shown by the CREST results, but doesn't quite match it.
There is another difference between the two procedures with as-yet unknown consequences. During CAS, when the catheter is pushed through the narrowing in the carotid artery, platelets and bits of fatty plaque break free and get into the bloodstream. Umbrella-like devices are used to capture these particles (called emboli) before they get too far, but some escape and reach the brain. Surgery releases far fewer particles because the artery is clamped before the operation begins. Whether this shower of particles affects brain function is a matter of research and dispute.
Choosing a procedure
So, what to do if you have a narrowed carotid artery?
If it isn't too severe (less than 70% narrowed) or causing any symptoms, your best bet is medical therapy. If the narrowing is severe, or if it has already caused a transient ischemic attack or full-blown stroke, carotid artery surgery has a small edge over CAS for most people.
More important than which procedure you choose is the experience of the doctor who will perform it and how well his or her patients fare afterward. Don't be shy about asking for numbers: How many carotid artery procedures do you perform each year? What percentage of your patients have a stroke or die from the procedure? These are tough questions to ask, but they are the most important ones in your decision-making process.
Health.harvard.edu
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