Using stents to prevent strokes
When a blockage in the neck’s carotid artery breaks off, it travels quickly -- and often devastatingly -- to the brain, causing a stroke.
To prevent this from happening, doctors have had to cut into the neck and artery, remove the blockages, then sew the vessel back together. The procedure requires general anesthesia, however, and a hospital stay of up to four days.
Doctors now have an alternative.
The Food and Drug Administration has approved a stent and filter system that can accomplish the same goal, but with a far less invasive procedure.
Physicians called the approval a significant development in the push toward less invasive medicine, enabling patients to reduce hospital stays, recovery time and overall costs.
“The treatment and prevention of strokes is entering a new phase, and the phase of doing surgery on sick patients is coming to an end,” said Dr. T. Anthony Don Michael, a Bakersfield cardiologist.
The stent and filter system consists of a small metallic mesh tube with a balloon catheter that expands to dislodge the plaque, then traps it in an umbrella-like filter to prevent it from moving to the brain and causing a stroke.
The stent, inserted through an incision in the groin and threaded through the artery to the neck, could eventually supplant the present “gold standard” for treating carotid blockages, known as carotid endarterectomy surgery, which is undergone by about 167,000 Americans annually. Insertion of the stent requires only local anesthesia and typically an overnight precautionary hospital stay.
Though the FDA approved the stent for use only in the relatively few patients with 80% artery blockage or those who are considered at high risk for surgery because of other factors, approved devices are typically used by physicians for lower-risk groups as well. The manufacturer, Guidant Corp., is also conducting clinical trials to establish that the stent is as safe as surgery in lower-risk patients; once completed, in 2007 or 2008, Guidant will seek approval for use in all patients.
The stent and filter system for the carotid artery adds to the growing list of procedures that can be done with minimally invasive operations. Patients who might once have needed heart bypass surgery often can have a coronary stent inserted, and gallbladders now can be removed laparoscopically. Stents have been approved for use in the last decade for coronary, kidney and leg embolisms, although this is the first approved in the U.S. for the artery to the brain.
About 500,000 Americans suffer a first stroke each year and 200,000 have recurring strokes, according to the American Heart Assn., causing about 280,000 deaths annually. An estimated two-thirds of those are due to blockages in the carotid artery. Strokes can be devastating to survivors, affecting the brain as well as the body, leaving thousands severely disabled and adding $53 billion annually to the U.S. healthcare bill for long-term hospital and nursing home care.
Still, the stents are not without risks. They were shown to have about equal the risk of the surgical procedure -- the standard they were required to meet for FDA approval.
“Carotid endarterectomy reduces the risk of stroke by 50% at the end of one year,” said Glenn Stiegman, biomedical engineer for the FDA whose division approved the Guidant stent. “This device was shown to be the equivalent of that reduction in patients who don’t have a reasonable availability of surgery in terms of their risk.”
About 8% of the high-risk patients were shown to die or suffer another stroke within 30 days with the stent and 10% at the end of one year, about the same as those who had the more invasive surgery. Guidant says initial results of its clinical trials in the U.S. -- and results from its use in Europe since 2001 -- indicate that in lower-risk groups, serious adverse consequences drop to about 3%.
Still, the stent is far from foolproof.
Cardiologist Dr. Ray Matthews of Good Samaritan Hospital in Los Angeles, one of several surgeons using the device in Guidant’s clinical trials, called it a “great alternative to surgery.” But he said the risk of stroke from the procedure was still the No. 1 concern -- and not just from the artery being worked on.
Carotid arteries run on both sides of the neck to the brain. In about 25% of the patients who suffered adverse effects, the stroke came from the other side -- meaning that debris was disrupted from lower in the body by the catheter being pushed through the artery and traveling to the side of the brain not supplied by the artery being worked on. “This is not a freebie,” Matthews said. “There will still be a risk to manipulating catheters.”
Matthews also said other possible side effects were not assessed in the trial, including potential damage to the nerves surrounding the carotid that can cause facial paralysis. “It happens maybe 1% or 2% of the time, but it’s 100% if it’s you.”
Guidant expects to sell the stent, which it has been developing for nine years, for about $3,600. The carotid stent is larger than coronary stents and much more flexible than the rigid coronary stent to allow for neck movement, such as leaning while talking on the phone.
Carotid stents already are in use in Europe. Stents by companies such as Johnson & Johnson are expected to be approved in the near future by the FDA.
Asked why the U.S. has taken much longer to allow the devices here, Stiegman said the FDA had not been reluctant to approve or disapprove the studies. “It’s up to the companies to come in with valid scientific evidence to show they are safe and effective.... Guidant was able to show they were safe and effective in their study.”
