Cardiac troponin (cTn) is the keystone for diagnosis of acute myocardial infarction (AMI). We examined the analytical and clinical diagnostic characteristics of the ACCESS hsTnI assay in a United States (US) population.
All measurements and studies were conducted using a lithium heparin matrix. Sex-specific 99 percentile upper reference limits (URLs) were determined for 1,089 healthy women (54.6%) and men using non-parametric statistics. High-sensitivity (hs) performance was assessed to determine if the total CV was ≤10% at sex-specific URLs, and if ≥50% of cTnI values for each sex exceeded the assay’s limit of detection (LoD). Precision, analytical measurement range, high-dose hook effect, and endogenous/ exogenous interferences were examined with CLSI guidance. Clinical characterization included serial sampling of 1854 suspected AMI subjects presenting to 14 US Emergency Departments. AMI was adjudicated by a panel of expert cardiologists. The study’s only exclusion was end stage renal disease.
99 percentile URLs were 11.6-, 19.8- and 17.5-ng/L for respective female, male and all-subject populations. Total %CV was <8% from 6.8 to 19,000 ng/L, and 90%, specificity >85%; and negative and positive predictive value were ≥99% and >60%, respectively.
Analytical and clinical performance of the ACCESS hsTnI assay meets the definition of a hs cTn method. The ACCESS hsTnI assay has good precision over a wide range, no significant interferences, and sensitivity >90% and NPV≥99%. Performance is appropriate for aiding in AMI diagnosis.
Approximately 7 million people in the United States present to emergency departments (ED) each year with signs and symptoms suggestive of the acute coronary syndromes (ACS), a continuum of cardiac ischemia that spans from stable angina to acute myocardial infarction (AMI). Of these, about 20% of patients (1.3 million) are eventually diagnosed with unstable angina or acute myocardial infarction . Rapid and accurate identification of AMI patients is important for preventing mortality and avoiding unnecessary procedures, lengthy waiting time in EDs, patient anxiety, and associated healthcare costs . During the last decade of the 20 century, evidence demonstrated that cardiac troponin (cTn)T and cTnI have excellent cardiac tissue specificity, as well as high diagnostic accuracy for AMI compared to other biomarkers for assessing myocardial injury . In 1999, the first Global Task Force was assembled and promulgated the consensus recommendation that cTn is the sole biomarker required for diagnosis of AMI . This guidance has been consistent through development of the second , third , and, most recently in 2018, the fourth  Global Task force documents. The 4 Global Task Force included a focused discussion of myocardial injury and included detailed information on cTn analytic issues, use of Electrocardiogram, and the application of imaging for assessing myocardial injury and AMI . The essential role of cTn is also articulated in AHA/ACCF evidence-based guidelines . Evidence-based guidelines from professional societies including the AACC Academy  and the European Society of Cardiology  are unanimous in recommendations that cTn should be the sole biomarker for AMI diagnosis and risk stratification. Currently there are two general classes of cTn assays used in most laboratories worldwide. The first have been coined Contemporary cTn Assays to distinguish them from early generation tests having less satisfactory analytic performance . The second type of generally available cTn tests are referred to as high-sensitivity (hs) cTn assays, which according to the AACC Academy and IFCC Committee on Clinical Applications of Cardiac Bio-Markers (C-CB) must meet specified criteria . For over 10 years Beckman Coulter has been developing a cardiac troponin assay with enhanced sensitivity . The US final form of this assay is available and has been termed the Beckman Coulter ACCESS High Sensitivity Troponin I (hsTnI) assay. The aim of this study was twofold: (i) characterize the analytical performance of the ACCESS hsTnI assay on the Access 2 Immunoassay System (Beckman Coulter, Inc., Chaska, MN); and (ii) assess the clinical performance ACCESS hsTnI assay as an aid in the diagnosis of acute myocardial infarction (AMI) METHODS AND MATERIALS: Beckman Coulter ACCESS hsTnI Assay.
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