Drug-releasing stents, till recently the rage among doctors treating patients with blocked arteries, do not seem as promising now. Studies currently link them with a low, but serious risk of fatal complications arising from blood clots.
The research by American scientists in two different studies published in the Journal of the American Medical Association show that many doctors have stretched the limit of their use- testing the effectiveness of such stents, even in unapproved conditions.
Drug-releasing stents or drug- eluting stents refer to stents, which have impregnated drugs that release slowly, in order to keep arteries open. The previous models with such drugs were plain metal stents i.e. wire-meshed tubes used to prop up de-clogged arteries.
When they were first approved for U.S. sale three years ago, the drug-infused devices were heralded as a revolution because they dramatically reduced the chances of an artery closing again.
The newer devices quickly supplanted the older bare-metal versions, generating almost 90 percent of all stent sales by early 2006 and creating a $6 billion market.
Yet studies reveal that off-label or untested use of drug-coated stents make up almost half of all uses of these devices for doctors treating blocked coronary arteries.
However, even though the risk for complications is higher with off-label use, the absolute rate for patients are still low overall, the researchers say.
In one study of 5,541 patients, Dr. Nirat Beohar of Northwestern Memorial Hospital in Chicago and colleagues found the risk of death, heart attack or blood clots more than doubled 30 days after drug-eluting stents were used in patients with conditions such as acute heart attack.
But the overall complication rate was relatively low at 2.5 percent, despite their use in high-risk patients.
Says Dr. Charles Davidson, one of the study's authors:'I look at this study as being very reassuring. Once you adjust for the more complex patient, there really is no safety issue.'
According to Davidson, drug-eluting stents are slightly less effective at keeping arteries clear in these sicker patients, but they are still much better than bare-metal stents because there are far fewer instances of restenosis, or artery reclogging.
In a second study of 3,323 patients treated with drug-eluting stents in 2004 and 2005, 54.7 percent of the patients were treated off label.
'Clinicians should be cautious about extrapolating the benefits of drug-eluting stents over bare metal stents,' the researchers were quoted.
So, what should a patient choose in this situation?
Robert A. Harrington of Duke University and director of the Duke Clinical Research Institute opines that the problem is that the U.S. device-safety system is flawed. There simply isn't a reliable system for systematically following up on and reporting what happens when newly approved implanted devices are used in the real world.
So what patients should do, Harrington says, is ask to their doctors about the evidence that a drug-coated stent would be effective and safe for them as individuals.
If a patient is in the 'on-label' group, the evidence is good. If the patient is in the 'off-label' group, there isn't a lot of evidence and doctors should explain why they think a drug-coated stent's benefits might outweigh its risks.
Says Harrington:' Doctors need to say, yes, we know that when we use these devices off label, there is a higher risk.
'The doctor should say, 'Here is how I interpret the evidence available, and here is how it applies to your situation.' This does not mean don't use the stents outside their approved indications, but if you start to do that, you'd better have a pretty good reading on what the risks are.'
In conclusion, all experts stress one additional point: Anyone who gets a drug-coated stent, on- or off-label, must be willing to take anticlotting medications for a year or more.