High-sensitivity cardiac troponin assays for cardiovascular risk stratification in the general population

Cardiac troponins (cTns) I and T have long been the most successful cardiac-specific circulating biomarkers in cardiovascular (CV) medicine, having changed dramatically the diagnosis of acute myocardial infarction, while being independent predictors of outcome in several cardiac conditions and non-cardiac conditions. The latest-generation high-sensitivity (hs) cTn assays demonstrate both enhanced diagnostic performance and improved analytical performance, with the ability to measure detectable concentrations in a substantial proportion of the asymptomatic and presumably healthy populations. Given this unique analytical feature, recent evidence suggests that hs-cTn can be used for the stratification of CV risk in the general population. High-sensitivity cTn predicts future CV events, are responsive to preventive pharmacological or lifestyle interventions, change in parallel to risk modifications, and offer incremental risk prediction when added to well-established prognosticators. The implementation of CV risk stratification and prevention strategies incorporating hs-cTn requires further investigation to define the optimal target populations, timing of measurement, and preventive interventions. © The Author(s) 2020

Influence of Population selection on the 99th percentile reference value for cardiac troponin assays

OBJECTIVE:We sought to determine the effect of patient selection on the 99th reference percentile of 2 sensitive and 1 high-sensitivity (hs) cardiac troponin assays in a well-defined reference population. METHODS:Individuals>45 years old were randomly selected from 7 representative local community practices. Detailed information regarding the participants was collected via questionnaires. The healthy reference population was defined as individuals who had no history of vascular disease, hypertension, or heavy alcohol intake; were not receiving cardiac medication; and had blood pressure60 mL·min(-1)·(1.73 m2)(-1), and normal cardiac function according to results of echocardiography. Samples were stored at -70 °C until analysis for cardiac troponin I (cTnI) and cardiac troponin T (cTnT) and N-terminal pro-B-type natriuretic peptide. RESULTS:Application of progressively more stringent population selection strategies to the initial baseline population of 545 participants until the only individuals who remained were completely healthy according to the study criteria reduced the number of outliers seen and led to a progressive decrease in the 99th-percentile value obtained for the Roche hs-cTnT assay and the sensitive Beckman cTnI assay but not for the sensitive Siemens Ultra cTnI assay. Furthermore, a sex difference found in the baseline population for the hs-cTnT (P=0.0018) and Beckman cTnI assays (P<0.0001) progressively decreased with more stringent population selection criteria. CONCLUSIONS:The reference population selection strategy significantly influenced the 99th percentile reference values determined for troponin assays and the observed sex differences in troponin concentrations

Trial design for assessing analytical and clinical performance of high-sensitivity cardiac troponin I assays in the United States: The HIGH-US study

Background: High-sensitivity cardiac troponin I (hs-cTnI) assays have been developed that quantify lower cTnI concentrations with better precision versus earlier generation assays. hs-cTnI assays allow improved clinical utility for diagnosis and risk stratification in patients presenting to the emergency department with suspected acute myocardial infarction. We describe the High-Sensitivity Cardiac Troponin I Assays in the United States (HIGH-US) study design used to conduct studies for characterizing the analytical and clinical performance of hs-cTnI assays, as required by the US Food and Drug Administration for a 510(k) clearance application. This study was non-interventional and therefore it was not registered at clinicaltrials.gov. Methods: We conducted analytic studies utilizing Clinical and Laboratory Standards Institute guidance that included limit of blank, limit of detection, limit of quantitation, linearity, within-run and between run imprecision and reproducibility as well as potential interferences and high dose hook effect. A sample set collected from healthy females and males was used to determine the overall and sex-specific cTnI 99th percentile upper reference limits (URL). The total coefficient of variation at the female 99th percentile URL and a universally available American Association for Clinical Chemistry sample set (AACC Universal Sample Bank) from healthy females and males was used to examine high-sensitivity (hs) performance of the cTnI assays. Clinical diagnosis of enrolled subjects was adjudicated by expert cardiologists and emergency medicine physicians. Assessment of temporal diagnostic accuracy including sensitivity, specificity, positive predictive value, and negative predictive value were determined at presentation and collection times thereafter. The prognostic performance at one-year after presentation to the emergency department was also performed. This design is appropriate to describe analytical characterization and clinical performance, and allows for acute myocardial infarction diagnosis and risk assessment. Keywords: High-sensitivity cardiac troponin, Immunoassay, Analytical characteristics, Clinical performance, 99th percentile, Sex-specific 99th percentile cutoff