Almost 800,000 Americans suffer a stroke every year. Strokes are the third most common cause of death in the US, and are frequently disabling to those who survive. These sobering numbers are despite the substantial improvement in recent decades in stroke prevention through the use of medications that lower blood pressure and cholesterol.
This week’s hubbub relates to carotid arteries, the large arteries in the neck that carry blood to the brain. But before we dig into the details we have to understand that most strokes have nothing to do with any problem with the carotid arteries. Strokes have many different causes, including high blood pressure, aneurisms, and abnormal heart rhythms. One of these many causes of strokes is a buildup of cholesterol inside the walls of the carotid arteries. This fatty plaque buildup can break off the artery wall and float to the brain, where it occludes a small artery and causes a stroke.
When a stroke is caused by this severe narrowing of the carotid artery by cholesterol plaque, studies have shown that surgery (called carotid endarterectomy) to remove this plaque helps decrease the risk of a second stroke. The surgery is not a minor procedure and carries substantial risks.
For several years, researchers have speculated that a safer way to prevent strokes in patients with carotid artery plaque is to put stents (metallic mesh tubes) inside the arteries, much like the stents used in heart arteries to keep them open. The rationale was that placing a stent in an artery is a much less invasive and less risky procedure than actually operating on it, so the hope was that stenting would be safer and just as effective.
That hope hasn’t yet materialized.
Several earlier trials showed that surgery prevents subsequent stroke better than stenting. Two large randomized trials which reported their results this week add confusion, not clarity to the issue. A large study, the Carotid Revascularization Endarterectomy versus Stenting Trial, just released results suggesting that stenting is as safe as surgery for carotid narrowing. A second trial, the preliminary results of which were just published in the British medical journal Lancet, reaches the opposite conclusion – significantly more strokes in the stenting group than in the surgery group.
So for the time being, surgery is still the proven standard for fixing narrowed carotid arteries that have caused a stroke. But we shouldn’t forget the bigger picture – keeping blood pressure and cholesterol low prevents many more strokes than fixing carotid arteries after they’ve already narrowed.
Wall Street Journal article: Big Studies On Neck-Artery Stents Show Different Findings
New York Times article: Study Finds Stents Effective in Preventing Strokes
Study in The Lancet: Carotid artery stenting compared with endarterectomy in patients with symptomatic carotid stenosis (International Carotid Stenting Study): an interim analysis of a randomised controlled trial