June 2, 1999 Dallas, June 1 -- Two clot-thinning drugs may be better than one for treating heart attacks, according to results of new study that appears in today's issue of Circulation: Journal of the American Heart Association.
One drug, called a thrombolytic, dissolves blood clots. The second drug, a platelet IIb/IIIa receptor blocker, keeps platelets from clumping and forming the blood clots that can obstruct blood flow and thereby trigger a heart attack or stroke. The platelet blockers, sometimes called "super aspirin" are more potent than aspirin. They are also administered through an intravenous drip or infusion.
According to lead investigator of the study, Elliott Antman, M.D., director of the Coronary Care Unit at Brigham and Women's Hospital, Boston, "The trial tested the hypothesis that the platelet blocker is a potent and safe addition to thrombolytic regimens."
Results of the new study, called the TIMI 14 trial, are so impressive, that researchers say that many individuals with heart attacks who otherwise would require angioplasty or bypass surgery to restore blood flow to the heart may be treated instead with both drugs. Angioplasty involves using a narrow tube with a deflated balloon on its tip that is passed into the narrowed part of the artery. When the balloon is inflated, the blockages or blood clots are pushed aside, allowing blood to flow through. Bypass surgery is an operation that uses blood vessels "borrowed" from another part of the body to go around clogged coronary arteries to reestablish blood flow to the heart.
According to J. Ward Kennedy, M.D., who wrote an accompanying editorial, the investigators have "made a major contribution to the management of acute myocardial infarctions (heart attacks)"-- and identified a therapy, which will likely prove to be equivalent or superior to opening blood vessels with medical procedures such as angioplasty.
The study included 888 individuals who had suffered a heart attack. Patients were treated with one of four therapies; alteplase, alone, abciximab alone or abciximab with reduced doses of alteplase.
Each patient received an angiogram, a visualization of the blood vessels that uses X-rays to determine how quickly the drugs dissolved blood clots in the vessel. The study examined the ability of the drugs to dissolve blood clots within 60 and 90 minutes. The study showed that 72 percent of heart attack victims who received abciximab plus half the standard dose of alteplase achieve optimal blood flow in their arteries within 60 minutes of treatment compared with only 43 percent of patients treated with alteplase alone. Within 90 minutes, 77 percent of patients treated with combination therapy achieved this level of blood flow, compared with 62 percent given alteplase alone.
Clot-buster drugs currently are the standard therapy for treating heart attacks. However, they are not always effective and many individuals develop recurrent blood clots.
"By enhancing the effects of clot-busters, abciximab may improve the treatment for heart attacks, and allow more patients to be treated with drugs rather than angioplasty and surgery," says Antman.
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