Higher Dose of Clot-Buster Is Better Before Artery Procedure
Twice as much Plavix halves the number of deaths, heart attacks, study finds
FRIDAY, May 11, 2007 (HealthDay News) -- Cardiologists should be giving more of the clot-preventing drug Plavix than is now recommended before performing the artery-opening procedure called angioplasty, a new study says.
The analysis of 10 previous studies found that giving angioplasty patients double the current recommended dose of Plavix -- 600 milligrams rather than 300 -- cut the combined risk of heart attack and cardiac death by half, according to Dr. Anthony Abbate.
Abbate, an assistant professor of medicine at Virginia Commonwealth University, was expected to present the findings on Friday at the Society for Cardiovascular Angiography and Interventions' annual meeting, in Orlando, Fla.
The higher dose did not increase the risk of serious bleeding, a major concern with Plavix, the analysis found.
"The evidence shown by this meta-analysis is very powerful," said Dr. Gregory Dehmer, president of the society and a professor of medicine at Texas A&M College of Medicine. "Although Plavix is powerful stuff, the meta-analysis did not find an excessive amount of bleeding. So we have a lower risk of myocardial infarction [heart attack] with no significant increase in adverse side effects."
The 10 studies analyzed by Abbate and Dr. Giuseppe G. Biondi-Zoccai, an assistant professor of cardiology at the University of Turin in Italy, included 1,500 patients who had angioplasty. Most had either 300 milligrams or 600 milligrams of Plavix before the procedure.
The incidence of cardiac death or nonfatal heart attack was 50 percent lower in the following 30 days in those getting the higher dose of Plavix. Only 3.1 percent of those getting the 600-milligram dose had in-hospital heart attacks, compared to 6.4 percent of those getting the 300-milligram dose. The overall 30-day incidence of death or heart attack was 3.8 percent for the higher dose and 7.3 percent for the lower dose, according to the study.
"This research has important clinical and cost implications," Biondi-Zoccai said in a prepared statement.
Current guidelines by the American Heart Association, the American College of Cardiology and the Society for Cardiovascular Angiography and Interventions say that physicians should "strongly consider" giving 300 milligrams of Plavix before angioplasty, a medical procedure to open narrowed or blocked blood vessels of the heart.
"Those guidelines are in the process of having an update," Dehmer said, adding that new guidelines are expected "in the next few months."
"In practical terms, many practitioners are concerned about the current recommendations," Dehmer said. "One concern is that should the patient require elective bypass surgery, does a higher dose of clopidogrel [the generic name of Plavix] increase the risk of excessive bleeding?
"Also there is the bleeding risk. It is addressed in this meta-analysis, which shows very minimal potential downside," he added.
But the final word is not in yet, said Dr. Marc S. Sabatine, associate professor in the cardiovascular division of Brigham and Women's Hospital in Boston. That will come from a major international study, to include up to 14,000 angioplasty patients, which is still enrolling participants, he said.
The smaller studies included in the current meta-analysis aren't definitive, Sabatine said, because there can be "publication bias," meaning that studies showing a positive result are more likely to get into print.
Timing also plays a role in treatment, he noted. Plavix must be activated in the liver, which takes about six hours, so giving it earlier makes it more effective.
But even with those side considerations, "many laboratories are considering switching to 600 milligrams," Sabatine said.
For more on angioplasty, visit the U.S. National Library of Medicine.