In a scientific paper in the May 27 issue of the New England Journal of Medicine, researchers report that a drug treatment can help prevent heart attack or sudden death in a certain group of high-risk individuals who are undergoing a procedure called angioplasty to restore blood flow to an obstructed artery.
This group of individuals who have unstable angina -- severe chest pain, even at rest -- are most likely to benefit from this drug if they have high levels of troponin T, a marker for heart muscle damage.
Unstable angina, a critical condition resulting from impaired blood flow to the heart muscle, is caused by fat-laden obstructions in the heart's arteries. This condition leads to over one-half million hospitalizations a year.
This high-risk group of people who have unstable angina are sitting on a potential time bomb -- one that could suddenly transform a narrowed coronary artery into a heart attack or death.
In this study, the researchers measured participants' levels of troponin T. People with normal hearts have very low blood levels of troponin T. Troponin T levels increase substantially within several hours after an unstable angina attack and peak at 10 to 24 hours. Not all people with unstable angina have elevated troponin T levels. However, for those who do, the drug abciximab in combination with angioplasty appears to be beneficial, according to the study published in the New England Journal of Medicine.
Richard C. Pasternak, M.D., American Heart Association spokesperson and director of preventive cardiology at the Massachusetts General Hospital in Boston, Mass., says, "This study is important because it raises the possibility that even after unstable angina occurs and the bells go off, heart attack can be prevented with medical therapy."
The drug, abciximab, is a blood-thinner. It keeps blood particles known as platelets from clumping and forming clots that block blood flow, leading to a heart attack or stroke. Abciximab is one of a group of platelet blockers that are sometimes called "super aspirins" because they are more potent than regular aspirin. These "super aspirins" are given by injection into a person's vein. The study results were based on blood samples of 890 patients who were, on the average, 61 years old. They all had serious unstable angina, defined as having at least one obstructed heart artery that could be effectively treated with angioplasty.
Patients were assigned to one of two treatment groups: an injection of abciximab from 18 to 24 hours before angioplasty plus continuous infusion of abciximab into the vein until one hour after angioplasty, or a matching pre-angioplasty injection and infusion during angioplasty of an inert substance (placebo).
Six months after angioplasty, among the individuals in the high-risk, unstable angina group who had high troponin T levels and received abciximab, 9.5 percent had heart attacks or deaths, compared with 23.9 percent of the people in the untreated (placebo) high-risk, unstable angina group who had high troponin T levels.