Clinical chemistry
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The clinical relevance of slightly increased circulating troponin concentrations in patients with stable coronary heart disease (CHD) several weeks after an acute event or CABG has not been fully evaluated. ⋯ Slightly increased hs-cTnT concentrations in stable CHD patients are associated with several cardiovascular disorders and predict long-term CVD events.
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New-generation high-sensitivity assays for cardiac troponin have lower detection limits and less imprecision than earlier assays. Reference 99th-percentile cutoff values for these new assays are also lower, leading to higher frequencies of positive test results. When cardiac troponin concentrations are minimally increased, serial testing allows discrimination of myocardial infarction from other causes of increased cardiac troponin. We assessed various measures of short-term variation, including absolute concentration changes, reference change values (RCVs), and indices of individuality (II) for 2 cardiac troponin assays in emergency department (ED) patients. ⋯ The short-term variations and IIs of cardiac troponin were low in ED patients free of ischemic myocardial necrosis. The detection of cardiac troponin variation exceeding reference thresholds can help to identify ED patients with acute myocardial necrosis whereas variation within these limits renders acute coronary syndrome unlikely.