|Posted by Pacific J Med Sci on December 10, 2010 at 10:00 AM|
Lipids Online (http://www.LipidsOnline.org)
August 27, 2009
MedWire News: Diagnosing myocardial infarction (MI) in patients presenting with chest pains could be improved with a new generation of cardiac troponin assays, study results demonstrate.
Two large, multicenter trials published in the New England Journal of Medicine compared the diagnostic performance of current cardiac troponin assays with a new wave of more biochemically sensitive assays. Since 1999, professional societies worldwide have recommended the use of troponin as the preferred biomarker for evaluation of patients with suspected MI.
The major limitation of current cardiac troponin assays is their low sensitivity at patient presentation, owing to a delayed increase in circulating levels of troponin. In the first of two studies evaluating a new generation of assays, Christian Mueller (University Hospital, Basel, Switzerland) and colleagues analyzed blood samples from 718 consecutive patients admitted to hospital with chest pains. A diagnosis of acute MI was confirmed in 123 (17%) patients. The researchers found that accuracy for detecting MI was higher in four novel cardiac troponin assays than in the standard test, with area under the receiver-operating characteristic (AUC) scores of 0.96 (Abbot-Architect Troponin I, Abbott Diagnostics, Abbott Park, Illinois, USA); 0.96 (Roche High-Sensitive Troponin T, F Hoffmann-La Roche AG, Basel Switzerland); 0.95 (Roche Troponin I); 0.96 (Siemens Troponin I Ultra, Siemens AG, Munich, Germany ) versus 0.90 (Roche Troponin T). Notably, the new generation cardiac troponin assays retained much of their diagnostic accuracy in patients who presented within 3 hours of the onset of chest pains, whereas the standard assay lost substantial power (AUCs: 0.93; 0.92; 0.92; 0.94 versus 0.76, respectively).
In a second study of 1818 patients presenting with chest pain, Stefan Blankenberg (Johannes Gutenberg University, Mainz, Germany) and colleagues similarly found a superior diagnostic accuracy for one new cardiac troponin assay over the standard test, with AUCs of 0.96 (Siemens Troponin I Ultra) versus 0.85 (Roche Troponin T). Blankenberg et al additionally went on to evaluate the effect of the new generation troponin assays on clinical management. Using the 99th percentile as a cut-off value, the clinical sensitivity for detecting MI was 63.7% for the standard assay and 90.7% for the new generation assay. However this was accompanied by a diminished specificity of the new generation assay compared with the standard test at 90.2% versus 97.2%.
Commenting on the findings in an accompanying editorial, David Morrow (Brigham and Women’s Hospital, Boston, Massachusetts, USA) said: “In these studies, the two groups of investigators showed that a new generation of sensitive assays for troponin improved overall diagnostic accuracy and thus functioned as a better test.
“However, their results also confirm a trade-off of superior clinical sensitivity for diminished clinical specificity for the diagnosis of MI.”
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a part of Springer Science+Business Media. © Current Medicine Group Ltd; 2009