Glycoprotein IIB/IIIA Receptor Inhibitors Markedly Benefit Patients
ORLANDO, FL -- The class of drugs known as glycoprotein (GP) IIb/IIIa receptor inhibitors has been shown to significantly save lives, reduce heart attacks, and decrease the need for angioplasty, according to the results of a meta-analysis by the Duke Clinical Research Institute (DCRI) at Duke University Medical Center.
The meta-analysis includes more than 30,000 patients randomized in 12 clinical trials involving four GP IIb/IIIa inhibitors, which are monoclonal antibodies that clog up receptors on platelets in the blood, blocking clots from forming. They could potentially be used in the more than one million patients who come to the hospital with severe chest pain but who do not have the classic signs of a heart attack as measured on an electrocardiogram. Currently, only aspirin is used to treat this group of patients.
The study was prepared by Dr. Robert Califf, director of the DCRI, for presentation at the American Heart Association's (AHA) annual scientific session.
He found that 30 days after treatment, the drugs saved 3.5 lives per 1,000 patients; a total of 22 deaths or heart attacks per 1,000 patients; and a total of 30 deaths, or heart attacks, or angioplasty procedures per 1,000 patients. These results were highly statistically significant, Califf said.
"This analysis leaves no doubt as to the benefit of this class of drug," said Califf, who conducted the study as part of the AHA-sponsored debate, "Controversies in Clinical Cardiovascular Disease."
"Two other things are very important about our findings in this class of drugs," he said. "First, more than 30,000 patients have been studied and the results analyzed before most of these drugs reached the market. Second, the worldwide community of cardiovascular investigators has made it possible to gather these data and have willingly shared them."
The four GP IIb/IIIa inhibitors studied all were intravenous drugs: eptifibatide, tirofiban, lamifiban, and abciximab. Only abciximab is available on the market, where it is known by the trade name ReoPro.
The 30,521 patients studied fell into two categories: those with non-ST-elevation acute coronary syndromes, usually referred to as unstable angina or chest pain; and those undergoing percutaneous revascularization with either angioplasty or stenting. They were randomized into 12 clinical trials around the world that compared the benefits of therapy with GP IIb/IIIa inhibitors versus placebo therapy. These patients also were given aspirin.
Because this meta-analysis looked at the effect of GP IIb/IIIa inhibitors as a class of drugs, rather than as individual drugs, "we cannot use this kind of data to arrive at conclusions about these agents individually," said Califf. "That will require head-to-head comparative trials, and those will certainly follow."
ReoPro is the subject of another meta-analysis, which also is being presented at the American Heart Association scientific sessions this week. That study, according to its principal investigator, Dr. James J. Ferguson, III, "puts to rest the concern that IIb/IIIa blockers may not affect hard end points. They do," he said. "IIb/IIIa blockers save lives. They are an effective therapy and a very valuable addition to our armamentarium." Ferguson is associate director of cardiovascular research at St. Luke's Episcopal Hospital and Texas Heart Institute in Houston.