Researchers have found that a new anti-platelet drug works more effectively in American patients than in patients from all other countries included in a large-scale international clinical trial.
The trial, called PURSUIT-which stands for Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy-was spearheaded by researchers from the Cleveland Clinic Foundation and the Duke Clinical Research Institute. The international trial was conducted from late 1995 to early 1997.
"PURSUIT is one of the largest experiences in this field," said Dr. Robert Harrington, associate professor of medicine, referring to the nearly 11,000 patients worldwide used in the trial. "It's a pretty sizable population to gain insight from."
Harrington is one of the primary investigators of the American patient subset of PURSUIT. A paper published in the Sept. 4 issue of Circulation focused on results and observations made from this group.
Eptifibatide, the drug tested in the trial, is part of a new class of drugs that is given to heart patients to prevent aggregation of bloodstream-clogging platelets. A total of 10,948 patients from 726 hospitals representing 28 countries were randomly treated with either eptifibatide or a placebo for 72 continuous hours.
Of the 4,305 patients from the United States, 11.9 percent of those treated with eptifibatide died or experienced a heart attack within 30 days of treatment, compared with 15.4 percent of those given placebos. In stark contrast, among patients from countries other than the United States, 15.6 percent treated with eptifibatide died or had a heart attack compared to 15.9 percent of placebo-treated individuals.
"The reduction of heart attacks or deaths in eptifibatide-treated patients [in countries other than the United States] was virtually insignificant," said primary author Dr. Michael Lincoff, associate professor of medicine at the Cleveland Clinic Foundation. "However, the drug showed significantly greater treatment effectiveness in the U.S. population."
Lincoff attributed this finding to the fact that more than 50 percent of the American trial population received some form of invasive treatment immediately following the 72-hour exposure. The procedures conducted were not required because of the drug itself, but were standard among U.S. institutions.
Lincoff believes that the drug was more effective in U.S. patients because invasive cardiac procedures such as angiography, angioplasty and bypass surgery are more common and performed earlier in America than elsewhere. "We found that with our more aggressive treatment patterns, a drug like eptifibatide has the most effectiveness," he said.
Although further research needs to be conducted to determine the exact cause of the drug's effectiveness, scientists recognize the rise of a broader global question. "This study is just one more piece of evidence in a series that show the way international differences in taking care of and providing treatment for patients can influence the response of any drug," said Harrington. In addition, just days before the paper's publication, the American College of Cardiology and the American Heart Association released a set of guidelines encouraging the use of drugs like eptifibatide.
Researchers hope this recommendation will spur changes to treatment protocol, primarily in increased incorporation of the invasive measures used by American physicians. "It puts pressure on physicians to adhere to specific guidelines [and thus change their] treatment procedures. Given our results, it seems even more compelling to stick to these standards," Harrington said.
Other researchers are also excited about how these guidelines will shape future heart disease protocol and research. "The trial results provide strong evidence that practices in the U.S. are much more effective than those used elsewhere," said Brigham and Women's Hospital's Dr. Chris Cannon, one of the most respected experts in the field. "These results support what physicians should be doing, especially when other treatments aren't as beneficial."
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