Carotid Angioplasty and Stenting

People with severe narrowing of the arteries in the neck that supply blood to the brain, a condition known as stenosis, are at risk of having stroke. These are called the carotid arteries, and a stroke usually occurs when they become completely blocked or when particles of cholesterol travel directly into the brain. Several studies have shown that carotid endarterectomy (CEA), which is surgery that opens and cleans out the artery, is better than medical treatment (controlling blood pressure, lowering cholesterol, taking aspirin as a mild blood thinner) in patients who have severe carotid artery narrowing. This holds true for patients without symptoms and those who have had strokes or mini-strokes (TIAs). The diagnosis of carotid stenosis is often determined by ultrasound, magnetic resonance angiography (MRA), or an arteriogram.

In otherwise healthy patients, the risk of stroke following CEA in centers where medical doctors are experienced in this procedure is often less than 1 percent, compared to the "best medical therapy," where the risk of stroke in patients without symptoms is 11-15 percent at five years, and even higher for patients having had TIAs. There are patients, however, who cannot have a CEA because of problems with their heart or lungs, and those who have had a previous carotid operation and have developed renarrowing. In this high-risk group of patients, the chance of suffering a stroke, dying, or having a heart attack following CEA is between 5 and 7 percent. For these patients, a new procedure, carotid angioplasty and stenting (CAS), may offer a better way of treating severe carotid artery narrowing.

CAS involves opening the carotid artery with a small balloon and then placing a stent (a metallic flexible mesh tube) into the artery; the stent acts as a "scaffold" to prevent the artery from collapsing after the balloon has been deflated and removed. The procedure is performed under local anesthesia and may be done by highly trained specialists in vascular surgery, cardiology, or radiology. Instead of surgery that involves cutting open the neck to reach the blocked artery, a small tube (sheath) is placed in the groin (much like a catheterization), and a catheter is maneuvered, under X-ray guidance, into the carotid artery in the neck. Dye is injected to see both the carotid artery in the neck and the arteries in the brain. Once a picture is taken, the patient is given blood thinner to protect against blood clots. A tiny umbrella filter is then opened above the narrowing in order to capture any clots or cholesterol that might break loose during balloon angioplasty or stent placement. After the artery is opened with a balloon and the stent is set in place, the filter is removed. The procedure takes about an hour to perform; patients usually stay overnight in the hospital and are monitored for any complications. Ultrasound studies of the stented artery will be performed during follow-up visits to see if the stent remains open.

A number of studies have been performed which assess the benefits and risks of CAS compared with carotid surgery. The SAPPHIRE trial, published in the fall of 2004, directly compared CAS using an umbrella filter and a special stent with CEA in patients who were at increased risk for surgery. Most of these patients had heart disease, heart failure, or emphysema that made surgery more risky, or had scarring in the neck from previous surgery that made the CEA difficult. The results showed that the risk of stroke or death was almost the same for surgery and stenting; however, the chance of having a heart attack (even a mild one) was much greater following surgery. The results of this study and others like it were used to receive U.S. Food and Drug Administration (FDA) approval for the use of carotid stents and filter devices. In addition, the Center for Medicare and Medicaid Services recently approved Medicare payment for CAS in patients who are at high risk for surgery.

A number of ongoing studies, including the Carotid Revascularization Endarterectomy vs. Stent Trial (CREST), will help determine the role of CAS and CEA in healthier patients. This study will compare the results of the two procedures. Patients have an equal chance of getting one procedure or another. It is decided by a process similar to flipping a coin. While the two procedures seem to have similar risks, we must determine, in head-to-head comparison, which is safer and longer lasting.

Currently, the "gold standard" for treating most patients with carotid disease is carotid endarterectomy. However, as new stents and filters are developed and technology advances, CAS may someday rival CEA for all patients.

About the Author: Timothy M. Sullivan, MD, is a vascular/endovascular surgeon, and Director of Endovascular Practice, Division of Vascular Surgery, Mayo Clinic, Rochester, Minnesota. He has specialized in endovascular procedures, has been performing CAS for nearly a decade, and is a well-known author and researcher in advanced treatments for vascular disease.