The coils, which researchers describe as mini-Slinkys, worked so well that scientists stopped enrolling new patients in the study earlier than they'd planned. A report on the findings appears in this week's issue of The Lancet.
Dr. Kieran Murphy, an interventional neuroradiologist at Johns Hopkins University in Baltimore and one of the trial center leaders, calls the findings "a major breakthrough" that will change clinical practice. However, he says there are currently only about 200 coil specialists in the United States, so many patients eligible for the devices won't have access to a doctor that can perform the procedure.
An aneurysm is the cardiovascular system's equivalent of a bubble on the side of a bicycle tire -- a potential disaster waiting to happen. As many as 18 million Americans have unruptured aneurysms and 30,000 suffer a burst every year. The ruptures are often catastrophic, leaving 15 percent of patients dead before they can reach a hospital. Half of patients die within a month, and many of the rest are left with crippling neurological problems.
Conventional treatment for ruptured aneurysms is to open up the skull, locate the offending vessel and pinch off the rupture to stop the bleeding. This procedure is highly invasive, requiring surgeons to delve deep into the brain, and it takes great finesse to avoid harming healthy parts of the organ.
Endovascular coils are also invasive. The small platinum springs -- which range in diameter from two millimeters to 20 millimeters -- are loaded into long catheters and threaded with the aid of X-ray imagery through the groin's femoral artery on up the body to the skull.
Once placed in an aneurysm the straightened devices collect into their coil shape, filling up the pocket. The presence of the metal stimulates clotting and, ultimately, scar tissue that seals off the bulge. Newer "bioactive" coils have drugs coating the platinum that hasten the healing process, though these weren't tested in the latest study.
The U.S. Food and Drug Administration approved the use of coils in both ruptured and unruptured aneurysms in 1995, and they have become widely used. However, doctors have little evidence of how they compare with surgery.
The latest study included 2,143 men and women at with ruptured aneurysms at 43 medical centers worldwide. Roughly half received the coils and half underwent surgery. All of the patients were equally good candidates for either procedure, a situation that doesn't always reflect real-world clinical experience. Murphy estimated that perhaps a third to 40 percent of aneurysm patients would fall into the either-or category.
After a year, 24 percent of the remaining 801 patients given coils had died or were seriously disabled, compared with nearly 31 percent of the 793 surgery patients still in the study, a difference of about 23 percent. The coil procedure reduced the risk of death by roughly 7 percent compared with surgery.
The rate of additional bleeding episodes after each procedure was low but appeared to be slightly higher in the coil group. "We will need to follow these patients over time for evidence" that the coils are letting blood escape, Murphy says.
Dr. Jacques Dion, a brain expert at Emory University in Atlanta who performs coil implants, says the new findings might change the standard of care for people with ruptured aneurysms. "It will become unethical not to propose the possibility of coiling in a scenario where both surgery or coiling can be done," says Dion, immediate past president of the American Society of Interventional and Therapeutic Neuroradiology.
Although the coil procedure is about 30 percent cheaper than surgery for unruptured aneurysms, in patients with bleeding the cost of closing the break is drowned by the expense of treating its fallout, which includes stroke. "You're still stuck with a very sick patient who's going to spend a lot of time in the intensive care unit," Dion says.
The international trial will be evaluating the cost-effectiveness of the two procedures over the next five years.
What To Do
For a look at how the brain coils work, try Johns Hopkins University. For more on interventional neuroradiology, try the American Society of Interventional and Therapeutic Neuroradiology.