Is the 99th Percentile the Optimal Reference Limit to Diagnose Myocardial Infarction With High-Sensitivity Cardiac Troponin Assays in Patients With Chronic Kidney Disease?

Abstract

The estimated annual incidence of myocardial infarction (MI) in the United States is ≈525 000 new attacks per year and ≈210 000 recurrent attacks.1 The large number of events results in many emergency room visits for diagnostic evaluation to determine the presence or absence of acute coronary syndrome (ACS) and the need for hospital admission. The third universal definition of MI requires abnormal cardiac biomarkers in the context of acute myocardial ischemia supported by clinical, ECG, or cardiac imaging findings.2 Cardiac troponin (cTn) is recommended as the preferred biomarker to document myocardial necrosis. A rise or fall of cTn with at least 1 value >99th percentile of a reference control population using an assay with total imprecision at the 99th percentile 99th percentile are recommended. Articles see p 2032 and p 2041 In the last few years, more sensitive cTn assays and high-sensitivity cTn (hs-cTn) assays have been introduced that allow more rapid diagnosis of myocardial necrosis and detection of smaller MI events than previously possible with the standard cTn assay. Many patients previously classified as having unstable angina are now able to be reclassified as having an MI with more sensitive cTn assays. Early detection of acute myocardial necrosis may allow the introduction of earlier treatment, which would reduce morbidity and mortality. However, detection of lower levels of cTn than was previously possible with older assays allows the detection of cTn in patients with stable coronary artery disease and in patients with nonischemic conditions associated with low-level cTn elevations in the absence of coronary disease, thus increasing the false-positive rate for MI diagnosis. This decreased specificity results in more complex triage in the emergency …