The study was limited, however, in that 95.8 percent of the patients studied were white and individual patient-level data from the studies could not be combined, researchers noted.
Last March, the U.S. Food and Drug Administration said Plavix must carry a "black box" warning on its label, alerting patients and doctors that some people don't metabolize the medication properly.
"Almost one in three patients is not receiving ideal protection from ischemic events when treated with standard doses of clopidogrel for coronary stenting," Mega said.
"Given how widely clopidogrel is used to treat patients with cardiovascular disease, determination of the optimal antiplatelet treatment doses or regimens for individual patients is needed to tailor therapy appropriately," she added.
The findings raise the question of whether routine genetic testing of Plavix patients is needed, but some experts say it's too early for that.
Dr. Gregg Fonarow, an American Heart Association spokesman and professor of cardiology at the University of California, Los Angeles, noted that a clinical alert issued in July by the American College of Cardiology and American Heart stated that "the evidence base is insufficient to recommend routine genetic testing at the present time in clopidogrel-treated patients."
"There is no information that routine testing improves outcome in large subgroups of patients," Fonarow said. "Further studies are needed to determine if routine genetic testing or platelet function testing and alteration of the antiplatelet regimen based on these findings will improve clinical outcomes."
Another expert, Dr. Valentin Fuster, a professor at Mount Sinai School of Medicine in New York City and author of an accompanying journal article, agrees that genetic testing isn't neces
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