FDA Panel Seeks Warning That Stents May Be Unsafe
Saturday, December 9, 2006
New drug-oozing stents widely used to prop open clogged arteries are associated with an increased risk of blood clots, heart attacks and death for the majority of patients receiving the devices, an expert panel concluded yesterday.
Based on the finding, the special 21-member Food and Drug Administration panel recommended that the agency issue new warnings to doctors and patients that the devices' safety has not been established except for relatively low-risk patients, for whom the stents were originally tested and approved.
"If you use the device outside that indication, you're going to have a higher incidence of complications," said William H. Maisel of the Beth Israel Deaconess Medical Center in Boston, who chaired the panel.
The panel stressed that the tiny metal-lattice struts, known as drug-eluting stents, offer advantages over older bare-metal versions for some patients, with the benefits outweighing the risks for the relatively healthy patients for whom the devices have been tested.
It remains unclear whether the devices are causing the complications in other patients; the side effects could be occurring because these patients tend to be sicker. But panel members concluded that until that question can be answered, doctors and patients should be alerted about the potential risks. Several members said they hoped that would make doctors more cautious about using the devices.
"Let's be more judicious about this. Let's be less indiscriminate," said Eric J. Topol of the Scripps Clinic in San Diego.
The panel also recommended that patients who have the stents take anti-clotting drugs for at least a year.
More than 6 million people worldwide have gotten the drug-coated devices, including perhaps 3 million in the United States. At least 800,000 new patients get them each year, making the stents the most common device used to treat heart disease and one of the most common medical procedures of any kind. The panel's recommendations apply to at least 60 percent of those patients.
The FDA is not bound to follow the recommendations, but an official said the agency would respond rapidly.
"There may be things that can be done relatively quickly," the FDA's Daniel G. Schultz said, noting that the warning could take the form of changes in the devices' labels and letters to doctors and patients.
The recommendations came on the second day of a sometimes contentious two-day meeting the FDA urgently convened to determine whether the risks of the devices outweigh the benefits.
The panel concluded that although the devices, compared with older bare-metal versions, may increase the risk of blood clots, drug-eluting stents do not appear to increase the overall risk of heart attacks and strokes when used in the kind of patients for whom they were originally intended. But a majority of patients get them "off-label," or not as intended, and tend to be sicker and have more-complicated conditions, such as diabetes, multiple blockages and blockages in narrower arteries.
In a packed hotel room in Gaithersburg yesterday, the panel listened to presentations from researchers from California, Illinois, North Carolina, Rhode Island, Washington and elsewhere who analyzed the latest data from large registries of patients who had received the stents since they were introduced three years ago. Although the results were mixed, several analyses found an increased risk of blood clots, deaths and heart attacks.
"Do we have evidence that the safety-efficacy balance might be different in the off-label? I think we've heard enough to suggest that that's the case," said Steven Nissen of the Cleveland Clinic.
More than 1 million U.S. heart patients undergo procedures every year to have blocked arteries opened with tiny balloons, after which stents are implanted to keep the vessels open. Scar tissue often grows around the stents, however, narrowing the arteries again and requiring patients to undergo the procedure repeatedly or to have bypass surgery.
The newer stents are coated with a polymer impregnated with drugs that are released slowly, inhibiting scar-tissue growth. Because the devices were shown to be highly effective, they were hailed as a major advance and quickly replaced bare-metal versions for most patients, though the newer stents were tested on and approved for only low-risk patients.
The FDA called for the meeting after studies looking at patients outside tightly controlled clinical trials indicated that a year or more after implantation, patients with drug-coated stents faced increased risks compared with those with bare-metal models. Some researchers have estimated the newer devices might be causing thousands of heart attacks and deaths a year.
Some researchers, along with Boston Scientific Corp. and Johnson & Johnson, which make the two drug-eluting stents sold domestically, say any risks from the devices are offset by the reduced need for repeated procedures and bypass surgery, which carry their own risks.
Patients who get the stents had been advised to take aspirin and the drug Plavix for three to six months to reduce the risk of blood clots. Recent studies have indicated that patients may need to take the drugs longer, perhaps indefinitely. But Plavix is expensive and increases the risk of serious bleeding.