A new study shows that brain stents add no benefit to stroke patients treated with drugs alone, and they actually increase the risk of death and subsequent strokes.

Brain stents are the latest in treatments for victims of stroke. Cutting edge medicine, they’ve steadily increased in popularity in recent years. Too bad they not only don’t work, but make matters worse.

A stroke occurs when the blood supply to part of the brain is cut off or critically reduced. Brain cells deprived of oxygen and nutrients begin to die within minutes. One way the blood supply can be cut off is if the blood vessel narrows too much for blood to pass. A major health risk following a stroke caused in this manner is yet another stroke in the same region as the first stroke. To prevent another stroke from occurring, doctors have been increasingly using stents to keep the artery open. Every year about 90,000 Americans suffer the kind of stroke that the stents are designed to prevent.

Boston Scientific’s Gateway-Wingspan stent system was approved by the FDA in August of 2005. A catheter on the device is inserted into the blood vessel and inflated to open the blockage. The stent, a metal mesh in the shape of a tube, is moved into the inflated catheter and expanded. The stent remains permanently implanted, keeping the artery permanently open and preventing future blockage at that site.

Seems pretty straightforward. The study that won Gateway-Wingspan its approval seemed pretty straightforward too. In retrospect, however, the study is found to be “small” and “less rigorous.” It was pushed through the FDA under the Humanitarian Use Device Exemption, a kind of fast-track to approval for treatments that target a relatively small number of individuals. The incentive to rigorously test these treatments is diminished. As the FDA explains: “A device manufacturer’s research and development costs could exceed its market returns for diseases or conditions affecting small patient populations.”

The current trial, thankfully, does not concern itself with market returns. Called SAMMPRIS for Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stentosis trial, it compared the outcome of patients who had recently suffered a stroke and were treated with either a stent and drugs to those who received drugs alone. They began enrolling patients in November of 2008 with plans of evaluating a total of 764 patients. By April 5, 2011, with only 451 patients enrolled, they had seen enough. The analysis at that point showed that the 14.7 percent of the patients with the Gateway-Wingspan stent plus the drugs suffered another stroke or died 30 days after surgery. Meanwhile, only 5.8 percent of the patients who received drugs alone had a stroke or died in that time. The near 2.5 times increased risk for stent patients was substantial enough for the SAMMPRIS group to stop the trial.

It’s clear from the study that the brain stent makes matters worse for the patient but it is unclear why. One hint may come from the abnormally high amount of hemorrhaging they saw. Placing stents in the carotid artery – the main artery that delivers blood to the brain – rarely results in hemorrhaging. But almost one-third of the patients with intracranial stents in the current study showed hemorrhaging. The authors speculate that the abnormal amount of bleeding could have caused the recurrent strokes. It also suggests that placing stents in the smaller intracranial blood vessels is simply more technically challenging. Not only are they smaller, but they have many more twists and turns compared to the carotid artery. Placing stents in such a tricky location could cause tearing and dislodge bits of plaque or tissue that could clog a blood vessel elsewhere and cause a stroke.

In addition to saving their lives, avoiding the stent could save patients’ some bucks too. The drug regimen costs about $3,400 for the first year. Adding the Gateway-Wingspan ups the cost an additional $20,000. That’s a lot of money to pay for increased risk of death and more strokes.

“Without the trial, this procedure seemed destined to become the standard of care,” H. Gilbert Welch, a professor of medicine at the Dartmouth Institute for Health Policy & Clinical Practice, told the Washington Post. “With it, we have another example in which the best medical care is not the most medical care.”

But that’s assuming the study will have an impact on the treatment and prevention of stroke. Again, seems straightforward, but it’s actually quite complicated.

A damning report of coronary stents had only a temporary affect on the stents' popularity.

As an example, let’s consider the most widely used stents, the ones placed in coronary arteries. Coronary arteries supply blood to the heart. When these arteries are blocked – usually by cholesterol-containing plaques – the heart is deprived of blood, oxygen and nutrients. This leads to chest pain, shortness of breath, or, at worst, a heart attack. The use of coronary stents has exploded since they were first used in the mid-1980s. In 2004, over a million patients received coronary stents. Entitled COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation), a 2007 trial sought to determine if coronary stents with drugs offered more advantages than drugs alone in alleviating chronic chest pain caused by blocked coronary arteries. They found no difference in the outcome of the two groups in regards to death, heart attack, and stroke. It didn’t make matters worse, but it didn’t help either. The published study was called a “blockbuster,” Boston Scientific Corp. who makes the coronary stent saw their stock fall, and doctors saw usage of the stent begin to fall off.

For a time.

One month after the study was published the use of coronary stents in the US decreased by 13 percent. “But as the headlines about COURAGE faded, stentings soon began to rise again, and are now back at peak levels of about one million a year,” reported the Wall Street Journal.

Why would health care providers continue stenting despite the evidence that there’s no added benefit above drugs alone? As you might’ve guessed, it’s all about the money.

William Boden, the cardiologist who led the study, told the WSJ: “Most [cardiologists] haven’t voluntarily incorporated the COURAGE criteria into their practice. What’s going to continue to drive practice is reimbursement.” That is, as long as insurance companies continue to cover the coronary stents, doctors will continue to hand them out like candy. Adding to the inertia are patients with a hankering for the devices. Many doctors argued that suggesting to the patient they should take the drugs first, then implant the stents later if necessary, would only make the patients go seek another doctor who will provide the “best” treatment right now.

An important difference between the SAMMPRIS and COURAGE studies is that the former actually showed the stents to be harmful, compared to treating the stroke patient aggressively with drugs. No doubt, as with the COURAGE study, some doctors will find faults with the study. But we can only hope that, over time, data will trump agenda.

[image credits: Boston Scientific and Wall Street Journal]
image 1: Stent
image 2: Graph

Peter Murray was born in Boston in 1973. He earned a PhD in neuroscience at the University of Maryland, Baltimore studying gene expression in the neocortex. Following his dissertation work he spent three years as a post-doctoral fellow at the same university studying brain mechanisms of pain and motor control. He completed a collection of short stories in 2010 and has been writing for Singularity Hub since March 2011.