Washington, DC Stroke Prevention
Atherosclerosis of the carotid arteries is important because it is a major cause of stroke. There are about 750,000 new strokes per year in the United States and about 20% are associated with disease of the carotid arteries in the neck. Furthermore, about two-thirds of strokes occur without warning. While most strokes occur in patients without carotid artery disease, when a stroke does occur, it is important to know whether or not significant carotid disease is present. “Significant” carotid disease narrows the carotid artery more than 50%. The more severe the narrowing, the more concerning the disease.
Symptoms of Carotid Artery Disease (Carotid Stenosis)
Any adult patient who has a stroke or Transient Ischemic Attack (TIA or “ministroke”) should be checked for disease of the carotid arteries in the neck. However, most patients with carotid artery disease are asymptomatic. In these patients, carotid stenosis can be suspected when a noise, or bruit, in the neck is heard with a stethoscope during a physical examination. While there may be several causes for such a bruit, individuals over the age of 60, or with a history of stroke, myocardial infarction, coronary bypass or angioplasty PVD, and/or smoking are more likely to have carotid disease. Significant carotid stenosis is rare in the overall adult population (less than 2%), but is present in 20-30% of individuals with stroke or TIA and in 5-10% of patients with a bruit who are over 60, smokers or have a history of coronary or peripheral artery disease.
Diagnosis of Carotid Artery Disease (Carotid Stenosis)
Carotid artery disease is easily checked by Carotid Duplex Ultrasound. This is a simple non-invasive study that can detect plaque in the carotid arteries and determine the degree of blockage. You should talk with your primary care physician about whether or not you meet the criteria for a carotid ultrasound. Remember, not all insurance will pay for carotid ultrasound in patients without symptoms. Like PAD, the major long-term risk of carotid disease is myocardial infarction and cardiac evaluation along with risk reduction is very important in overall management.
Relationship between Stroke and Carotid Artery Stenosis
While there are many causes of stroke, carotid stenosis is thought to cause about 20-25% of strokes in adults. Patients who have a stroke and are found to have a carotid stenosis have about a 30% chance of experiencing a second stroke, most often during the first weeks to one month after the initial event. Therefore, adults who have a stroke should be checked for carotid stenosis. The importance of carotid disease in patients without symptoms of stroke is more controversial. Narrowing of the carotid arteries by more than 50% is present in 2-4% of individuals over the age of 65; however, most of these people will never have a stroke. About 60-70% of patients who have a stroke have no warning signs, and therefore, the only suggestion that they have carotid disease may be a bruit in the neck or finding narrowing with a Carotid Duplex Ultrasound. When carotid artery stenosis is found in an asymptomatic individual, the overall risk of stroke and death is increased. The risk of stroke increases with the degree of stenosis.
- Narrowing of the carotid arteries less than 50% is considered part of normal aging.
- Narrowing of the carotid arteries between 50-70% carries a low risk of stroke and should be monitored.
- Narrowing of the carotid arteries more than 70% carries a 2-4% risk of stroke per year (10-20% over five years).
There is a common agreement that the general screening of all individuals for carotid disease is not necessary. However, there are certain circumstances where the likelihood of carotid disease is increased and screening may be considered. Patients over 60 years of age, who have more than one of these factors in their history, should consider screening studies. These include:
- Patients with coronary disease or PAD
- Patients with a murmur (bruit) in their neck
- Patients with a history of stroke or “ministroke” (TIA)
Intervention for Carotid Stenosis
- Patients with Stroke or TIA: Any patient with symptoms of a stroke or ministroke (TIA) who has a carotid stenosis more than 50% should be considered for intervention. The more severe the stenosis the more likely intervention should be performed. Comparison of medical treatment and surgery (carotid endarterectomy) in patients with symptoms of stroke or TIA has been done in many thousands of patients over several decades. Surgery will reduce the risk of future stroke from 15-30% to less than 5% in these patients. Whenever possible surgery should be done within two weeks of first symptoms. There is little controversy over the role of surgery in symptomatic patients with stenosis greater than 50%.
- Asymptomatic Patients: All asymptomatic patients with carotid plaque should be treated by control of diabetes, cholesterol, blood pressure and smoking cessation as well as aspirin therapy and a statin. In patients with narrowing of greater than 70% who are otherwise healthy, intervention may be considered. Comparison of surgery added to medical management versus medical management alone in asymptomatic patients has also been studied in several thousand patients. The benefit in asymptomatic patients is not as great as in patients who have had stroke or TIA. The overall risk of stroke in asymptomatic patients with carotid stenosis more than 70% is about 2-4% per year (10-20% over five years). Surgery can reduce this risk to 5-6% over the same timeframe. In other words, most patients who have carotid stenosis without symptoms will not have a stroke and this risk can be further reduced by surgery. To benefit from surgery, asymptomatic patients should have a narrowing of more than 70% and a life expectancy of at least 3-5 years. The role of surgery is asymptomatic patients is not universally accepted.
The benefit of surgery depends on the experience of the surgeon performing the operation and the overall health of the patient. In general, a surgeon performing Carotid Endarterectomy should have a complication rate (stroke plus death) of less than 6% in patients with symptoms and less than 3% in patients without symptoms. Experienced surgeons often have complication rates significantly less than that. It is important to know the surgeon’s results before considering surgery.
Treatments for Carotid Artery Stenosis
Carotid Endarterectomy (CEA):This is the standard treatment for carotid artery stenosis and is a procedure has been perfected over more than 50 years. It involves a 4-6 inches long incision in the neck to expose and clean out the diseased carotid artery. The procedure can be done under general anesthesia or regional (block) anesthesia depending on the surgeon and patient preference. A hospitalization of 24-48 hours is routine. Post-operative pain is minimal and patients can return to normal activities in about a week. Experienced surgeons can perform CEA with complication rates of 3-4% in symptomatic patients and 1-2% in asymptomatic patients.
Carotid Artery Stenting (CAS): This procedure has been used to treat carotid stenosis for more than 15 years. It was initially used to treat patients who were felt to be at increased risk from carotid endarterectomy. Like other endovascular surgery, CAS is performed under local anesthesia through a puncture in the groin. Patients usually have a 24-hour stay in the hospital and are back to full activity within 48-72 hours. Complication rates for CAS are higher than those after CEA—6-8% for symptomatic patients and 3-4% for asymptomatic patients. Complications after CAS are also higher in patients over the age of 70 and in those with neurological symptoms. Because of this, CAS is only recommended in patients with symptoms of stroke or TIA when CEA is felt to be dangerous, and is not recommended for asymptomatic patients. Currently, Medicare and most insurance companies will not pay for CAS in patients who are asymptomatic unless they are in a clinical trial. Comparison of CAS and CEA based on many clinical trials is presented in the table below. It is important to discuss specific complication rates, including stroke, death, myocardial infarction and local site complications with the operator performing the procedure.
Comparison of Carotid Endarterectomy and Carotid Artery Stenting
|Carotid Stenting||Carotid Endarterectomy|
|Anesthesia||Local||General or Block|
|Hospital Stay||24 hours||24-48 hours|
|Return to Full Activity||2-3 days||7-10 days|
|Complication Rate (Stroke/Death)||6-8% for symptomatic patients 3-6% for asymptomatic patients||3-4% for symptomatic patients 1-2% for asymptomatic patients|
|Patients with Stroke or TIA||When Carotid Endarterectomy is “high risk"||All other patients|
|Asymptomatic Patients||Currently not recommended outside of clinical trials||Good surgical risk, life expectancy 3-5 years minimum|
Intervention Follow Up
After intervention, patients should be maintained on aspirin or Plavix (both if CAS is performed) and a statin. Plavix may be stopped in 2-3 months as long as aspirin is maintained. General risk factor reduction including smoking cessation is important. A postoperative ultrasound is usually done within the first month to check the results of intervention. Recurrence after either CAS or CEA is less than 10%, so ultrasound can be done at six months, 12 months and two years. If there is no evidence of recurrent disease at that time and the other carotid is normal, no further follow up is required. If disease is present in the other carotid, or recurrent disease occurs in the original artery, further follow up may be required.