CAROTID STENOSIS AND STROKE

Carotid stenosis is a narrowing of the artery in the neck that sends blood to the brain. When blood flow to the brain is compromised, neurologic symptoms occur. The narrowing is caused by the build up of cholesterol and calcium in a plaque, which is the problematic lesion in hardening of the arteries. Many such blockages cause no problem, but when they do, the result is a “mini stroke,” or a completed stroke. 

For decades, the treatment for carotid stenosis (arteriosclerotic blockage of a carotid artery) was carotid endarterectomy (surgical removal of the obstructing plaque). The potential for stroke was significant so aggressive treatment was thought to be warranted. If a patient was asymptomatic yet had a 70% or greater blockage of a carotid artery, he/she was a candidate for surgery. If the patient already had a TIA (transient ischemic attack, ie. “mini stroke”), he/she had an endarterectomy if the blockage was 50% or greater. This has been the standard of care for years, but now researchers are studying intense medical therapy as an alternative.

Carotid endarterectomies are still done, but medical therapy has come to the forefront and been shown to be effective at preventing stroke. By medical therapy I mean the usual things: intense STATIN therapy, blood pressure control, diet, exercise, weight control, and smoking cessation. These health-improving therapeutic measures are just as effective in the carotids as they are in arteries elsewhere. Of course, these preventive measures are a good practice every day of our lives.

Physicians at Kaiser Permanente of Northern California looked at the incidence of stroke in asymptomatic patients with a severe carotid stenosis who had not had carotid surgery and were treated medically. They studied 94,882 patients, 3737 of whom had significant carotid blockages. They found that over a five-year study period, those patients treated medically had a 4.7% chance of a stroke. That doesn’t sound bad, but any stroke is disaster. 

For comparison, a Chinese study of patients with carotid stenosis treated with endarterectomy, showed surgery was 100% successful immediately thereafter. However, at 30 days post-op, 4.05% of patients had had some type of stroke event, and at two years post-op 4.95% had had some kind of stroke (TIA, completed stroke, etc.) event.  The comparison is unfair, however, because patients in this study were not asymptomatic and had significant co-morbidities. They were worse pre-operatively so they had greater chance for problems post-operatively.

Another study of 1824 patients, 582 of whom were “unsuitable for surgery,” compared three treatment methods: endarterectomy, stenting, and “best medical therapy.” Of the total, 64.1% were symptomatic and 35.9% were asymptomatic. Best medical therapy was helpful only for asymptomatic patients, but it was nowhere near as helpful as surgery and stenting.

Bottom Line: Prevention of carotid stenosis with “best medical therapy” is the first and most important step. If, however, a patient acquires a narrowed carotid artery and is not having symptoms from it, medical therapy can be tried. According to this study, the incidence of stroke over five years is low.

Dr.G’s Opinion: I think if you have a carotid narrowing of 70% or greater, you’re running a risk if you don’t have surgery. Why leave a plaque there when you know it will result in symptoms in the future. A piece of plaque may break off and float up to the brain. For symptomatic and asymptomatic narrowing of the carotid artery, carotid endarterectomy (surgery) is the standard of care. Carotid stenting is an alternative for high risk surgery patients. For asymptomatic patients with a greater than 70% blockage, intensive medical therapy can be tried, but I think it should be reserved for healthy, non-smokers who have no symptoms and no previous neurologic events. Those patients are much less likely to have a stenosis in the first place. With the best possible medical therapy, there is still a nearly 5% chance of having a stroke over five years. If it were me, I would try medical therapy early as a preventive measure, but if I developed a stenosis of 70% or greater, I would opt for endarterectomy. If I don’t, I’m playing with disaster. 

References: Chang RW, Tucker LY, et al. Incidence of Ischemic Stroke in Patients with Asymptomatic Severe Carotid Stenosis without Surgical Intervention JAMA 2022 May 24/31;327(20):1974-1982.

Bruls S, Van Damme H, Defraigne J-O. Timing of carotid endarterectomy: a comprehensive review. Acta Chir Belg 2012 Jan;112(1):3-7.

Rerkasem K, Rothwell PM. Carotid endarterectomy for symptomatic stenosis. Cochrane Database Syst Rev. 2011 Apr 13;(4):CD001081.

Yang L, Liu J, Qi G, Li Y, Liu Y. The middle-term outcome of carotid endarterectomy and stenting for treatment od ischemic stroke in Chinese patients. Scientific Reports 2018; 8:1-7.

Mazzaccaro D, Stegher S, et al. Treatment of significant carotid artery stenosis in 1824 patients. J Cardiovascular Surg (Torino) 2015 Feb;56(1):107-118.