Originally Published IVD Technology January/February 2004
INDUSTRY NEWS
Cardiac testing sees new developmentsSeveral new IVDs have proven useful for predicting cardiac incidents. A new blood test may help practitioners decrease the risk of postsurgical heart damage. According to an article in the November issue of Critical Care Medicine, moderately elevated levels of troponin I in the blood of postsurgical patients in the intensive care unit (ICU) may indicate ongoing heart injury and are associated with longer hospital stay and increased risk of death.
According to the study, "Moderate elevations of serum troponin I, which are below the threshold required to diagnose overt myocardial infarction, may reflect ongoing myocardial injury in the critically ill and are associated with a higher mortality rate and longer hospital and intensive care unit length of stays."
Senior author of the report, Gregory J. Beilman, MD, associate professor of surgery and anesthesia at the University of Minnesota (Minneapolis), noted, "We think that evaluating troponin levels may be a physiologic stress test."
According to the Society of Critical Care Medicine (Des Plaines, IA), 15% of patients admitted to the ICU will have an unrecognized heart injury. The importance of measuring troponin levels may be realized through further investigation. Joseph E. Parrillo, MD, editor-in-chief of Critical Care Medicine, says, "The findings suggest that subclinical cardiac injury may occur during critical illness and may identify patients with poor outcomes. Prospective trials will be necessary to confirm this association and to evaluate the possible ability of aspirin and beta-blockers to improve outcomes in such patients."
In addition to testing for troponin I levels, testing for myeloperoxidase (MPO) may prove to be important for predicting whether patients may be at risk of a heart attack. According to a report in the October 23 issue of The New England Journal of Medicine, inflammation is linked to adverse outcomes in patients with acute coronary syndromes. There appears to be a relationship between elevated levels of MPO, an abundant leukocyte enzyme, and both inflammation and cardiovascular disease.
MPO is produced when arteries are inflamed and contain fatty deposits that may induce adverse cardiac events when ruptured. The investigators assessed the plasma levels of MPO and investigated the role of these levels as a predictor of the risk of heart attack in 604 patients presenting with cardiac pain.
The investigators found that a single measurement of plasma MPO can independently predict the early risk of myocardial infarction, as well as the risk of major cardiac events in the following 30-day and 6-month periods. Unlike testing for troponin T, creatine kinase MB isoform, and C-reactive proteins, MPO levels identified patients at risk for cardiac events in the absence of myocardial necrosis. As a result, testing for MPO levels may be useful for risk stratification among patients presenting with chest pain.
An additional predictor of the risk of myocardial infarction may be found in the genome. Roche Diagnostics (Basel, Switzerland) and deCODE genetics (Reykjavik, Iceland) have identified alleles of a gene that confer approximately twice the average risk of myocardial infarction in carriers.
The companies plan to develop a DNA-based test that scans for two forms of the gene in an effort to identify individuals who are at an elevated risk of suffering a heart attack. The two haplotypes are each delineated by six single nucleotide polymorphisms within the affiliated locus. According to Roche, the haplotypes confer a risk equal to or greater than those associated with other risk factors including smoking, high blood pressure, elevated cholesterol, or diabetes.
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