To print: Select File and then Print from your browser's menu --------------------------------------------------------------------------------------- Title: Cardiac Test Provides Fast, Early Prediction of Death Risk URL: http://www.pslgroup.com/dg/D4DE.htm Doctor's Guide October 30, 1996
BOSTON, Oct. 30, 1996 -- An existing test manufactured by Dade International for diagnosing acute myocardial infarction also provides a quick, early and specific measure of the risk of death among patients diagnosed by conventional tests as having unstable angina, according to a study published Oct. 31 in the New England Journal of Medicine. The test identifies cardiac troponin-I, a protein found in the bloodstream only after heart damage has occurred. Researchers at Brigham and Women's Hospital in Boston found that angina patients with an increased level of cardiac troponin-I had a significantly higher risk of death after 42 days. The risk increased with higher levels of cardiac troponin-I, the study reported. In addition, patients with an elevated level of cardiac troponin-I who came for treatment six hours or more after the onset of chest pain had a much higher risk of death than those who came earlier. Cardiac troponin-I is not detectable in the plasma of healthy patients and, unlike other diagnostic markers, occurs only when there has been damage to the heart muscle. This non-enzymatic protein is released soon after cardiac injury and stays in the bloodstream for longer periods, up to 10 days, allowing for late diagnosis of myocardial infarction, which is important when patients seek medical attention several days after the event. Tests for other cardiac serum markers such as troponin-T and CK-MB (the MB isoenzyme of creatine kinase) can take as long as 45 minutes to process, while this particular test for cardiac troponin-I takes 10 minutes. Cardiac troponin-I was cleared by the FDA and has been on the market in the United States since August 1995. Elliott M. Antman, M.D., director of coronary care, Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, and principal investigator of the study, wrote in the New England Journal: "In managing patients with unstable angina and non-Q-wave myocardial infarction, it is desirable to identify a serum marker whose release is closely related to the degree of myocardial damage, is more sensitive than current markers, provides prognostic information, and can be measured in a time frame that permits implementation of treatments to minimize further necrosis." In the study reported in today's New England Journal of Medicine, cardiac troponin-I appeared to satisfy those requirements. "The development of unstable angina and non-Q-wave myocardial infarction indicates that a patient has entered a phase of ischemic heart disease associated with an increased risk of short term mortality that is intermediate between that seen in chronic stable exertional angina and Q-wave MI," wrote Antman. (Unstable angina results from temporary circulatory insufficiency to the heart that produces chest pain, but without damage to heart tissue. Non-Q-wave myocardial infarction is a form of heart attack characterized by moderate amounts of permanent damage to the heart muscle but frequently associated with only minor changes on the patient's electrocardiogram.) In the past, emergency department physicians typically have had to make diagnoses and develop treatment plans based on markers less specific than cardiac troponin-I, on electrocardiograms, and on their patients' age and general physical condition. Now, Antman and his co-authors wrote, "Elevated levels [of cardiac troponin-I] provide prognostic information beyond that contained in the electrocardiogram and demographic characteristics and therefore permit early identification of patients at increased risk of mortality." "It is now possible to move away from using markers that confirm decisions that have already been made and on to novel markers that provide clinically important diagnostic and prognostic information," said Mark Wolsey-Paige, Dade International's product line general manager for Stratus, the first test system cleared in the United States for measuring cardiac troponin-I. "Because it takes only 10 minutes to test for cardiac troponin-I, physicians have an important diagnostic tool at their disposal to develop a treatment plan that best ensures long-term recovery at a critical time following the occurrence of a heart problem." The research involved 1,404 patients, ages 21 to 76, participating in the federally funded Thrombolytic and Myocardial Ischemia (TIMI IIIB) trial, a randomized, multicenter study. The measurements of cardiac troponin-I were performed using the Stratus(R) II cardiac troponin-I fluorometric enzyme immunoassay manufactured by Dade International. The study was conducted by researchers in the Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital in Boston, in cooperation with researchers from the Maryland Medical Research Institute in Baltimore, and the University of British Columbia, Vancouver. The research was supported by grants from The National Heart, Lung, Blood Institute, the Data Coordinating Center, and Dade International. Dade International is headquartered in Deerfield, Illinois. The company has 5,500 employees in sales, research and manufacturing operations in 15 countries. The company provides product, systems and services for cardiac immunodiagnostics, clinical chemistry, hemostasis, microbiology and clinical laboratory quality control. --------------------------------------------------------------------------------------------- Copyright © 1999 P\S\L Consulting Group Inc. All rights reserved. Republication or redistribution of P\S\L content is expressly prohibited without the prior written consent of P\S\L. 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