MONDAY, March 15, 2010 (HealthDay News) -- After 12 months, giving aspirin alone to patients who have had stents implanted seems just as good as giving aspirin along with the blood thinner Plavix, a new study finds.
Researchers discovered that, after an initial year receiving the dual anti-clotting therapy, patients who went off Plavix and just took aspirin had the same rate of heart attacks and death as those patients continuing on the two drugs together.
The findings are unlikely to change what is happening in clinics, however.
"In general, this fits with current guidelines so it's not going to be practice-changing per se," said. Dr. Gurpreet Sandhu, an interventional cardiologist with the Mayo Clinic in Rochester, Minn. "The current guidelines from the American Heart Association and the American College of Cardiology indicate that people need to be on dual anti-platelet therapy for at least one full year after stent placement and then aspirin after that indefinitely."
"I don't think this trial will have any impact on practice in North America and I frankly hope that it won't because there's just not enough that we can draw out of this single trial to clarify what we ought to be doing in North American patients," added Dr. Kirk Garratt, clinical director of interventional cardiovascular research at Lenox Hill Hospital who, like others, is waiting for results from other major trials.
The study is to be presented Monday at the American College of Cardiology annual meeting in Atlanta and will also be published in the March 18 issue of the New England Journal of Medicine.
The U.S. Food and Drug Administration also recommends that patients get the combination therapy for at least 12 months after receiving a stent, Garratt said.
"After 12 months, it's dealer's choice. We don't have any good information to guide us," he said.
The study was led by researchers at the University of Ulsan College of Medicine, Asian Medical Center in Seoul, Korea, who also called for more trials to confirm or refute the data.
Stents are inserted to prop open arteries that have become narrowed due to plaque build-up. Once in place, though, the stents - tiny mesh scaffolds - can help spur dangerous blood clots.
These new results come not from one study but from two initially separate studies which were combined because both had flagging enrollment.
In all, more than 2,700 Korean patients were randomly assigned to receive clopidogrel (Plavix) plus aspirin for at least 12 months. Patients were followed for a median of just over 19 months.
Not only were there few differences between the two groups, there was even a sign of benefit in the group taking aspirin alone after 12 months.
"This was surprising [that there was no difference between the arms] and that those on aspirin alone even seemed to do a little bit better with respect to heart attack, stroke and death," Garratt said.
Nor were bleeding complications, always a concern with blood-thinning medications, any different between the two groups.
It is conceivable, however, that the results would not hold up in a different study population.
For instance, Asian populations have a high prevalence of an enzyme which is not very good at metabolizing Plavix, Garratt pointed out. The individuals studied here were likely all or nearly all Asian.
"It's likely that the Plavix group didn't have the same effect biochemically that we would have expected in a North American, Caucasian or mixed population," he said.
"This study essentially shows that you need to continue aspirin and clopidogrel for one full year and after that, you can stop clopidogrel and just keep people on aspirin and that is what people have been doing in general," Sandhu said. "There are some people who are concerned about the risk of clot formation on stents even beyond one year so many cardiologists and patients do continue with both aspirin and clopidogrel well beyond one year. [But], in the majority of cases, one year is all that is needed."
Plavix has long been the leader in clot-busting drugs, although new agents are now vying to take its place.
There's more on blood thinners at the American Heart Association.