Dec. 22, 1998 DALLAS, Dec. 22 -- Individuals whose heart attack was treated with a type of blood-thinning drug had a 30 percent reduced risk of dying within four days, according to a study of more than 30,000 heart attack patients reported today in Circulation: Journal of the American Heart Association.
Like aspirin, the drugs called a platelet IIb/IIIa receptor blockers keep blood platelets from clumping and forming blood clots that can trigger a heart attack or stroke. However, the platelet blockers, sometimes called "super aspirins" and sold under the generic names of eptifibatide, tirofiban, and abciximab, are more potent than aspirin. They are also administered through an intravenous "drip," or infusion.
"Aspirin is valuable for treating people with heart attacks and unstable angina -- severe chest pain that is often a sign of impending heart attack," says the study's lead author, David F. Kong, M.D., fellow at the Duke Clinical Research Institute in Durham, N.C.
"This new family of drugs works harder at making platelets less sticky, and they do it to a far greater degree than many other blood-thinners we've tried in the past."
The study, conducted by researchers at Duke, the Cleveland Clinic Foundation and the Green Lane Hospital in Auckland, New Zealand, analyzed 16 studies of about 32,000 heart attack patients. Participants received the platelet blocker drugs as part of their treatment for either heart attack or severe chest pain. Some individuals in the study received only the platelet blockers while others were treated with the drug plus angioplasty -- a procedure that uses a balloon-tipped catheter to restore blood flow in the blood vessel.
The researchers investigated how well the drugs prevented heart attacks, deaths from any cause, or the need for either angioplasty or bypass surgery, which reroutes blood flow around a blocked blood vessel. The researchers examined the drugs' effectiveness at three intervals: 48-96 hours; 30 days; and six months. "At the early time points, we found a statistically significant reduction in death," Kong says. "These drugs are saving lives."
Those who received the platelet blockers had a 30 percent reduced risk of all-cause death than those who did not receive the drugs. This meant that one person's life was saved for every 1,000 treated, says Kong.
There were almost 30 fewer deaths, heart attacks, or need for repeat angioplasty or bypass for every 1,000 patients treated, and the benefits were statistically significant through six months.
"Using the drugs saves lives, reduces the number of heart attacks, and cuts down on the number of individuals who need repeat angioplasty or bypass procedures," says Kong.
The individuals who particularly benefited from the drugs were those who also were treated with angioplasty, Kong says. In these individuals, the drug was administered just as the coronary arteries were being opened by inflation of the balloon-tipped catheters used for the procedure.
Studies now are underway to test the combination of platelet blockers and clot-dissolving medicines in heart attack patients.
Although use of the drugs is increasing for selected patients in hospitals -- and individual studies have indicated benefits for the drugs -- this new study quantifies the overall advantage and shows that the benefits last for as long as six months, notes Kong.
The other "mainstay" treatment for heart attack is clot-dissolving medicine, but Kong says these drugs are suitable for only 30-50 percent of heart attack patients in hospitals. Some individuals who cannot be given clot-busters -- those with unstable angina (indicating an impending heart attack), non-Q-wave myocardial infarction (mild heart attack), or undergoing balloon angioplasty -- may instead benefit from these platelet blockers.
Other authors are Robert M. Califf, M.D.; Robert A. Harrington, M.D.; James E. Tcheng, M.D.; and Vic Hasselblad, Ph.D. of Duke; Dave P. Miller, M.S.; David J. Moliterno, M.D.; A. Michael Lincoff, M.D.; and Eric J. Topol, M.D., of the Cleveland Clinic; and Harvey D. White, M.B. Ch.B, D.Sc., of the Green Lane Hospital.
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