A-017 Clinical Performance Evaluation of the Atellica IM High-Sensitivity Troponin I Assay to Aid in Risk Stratification for All-Cause Mortality and Major Adverse Cardiac Events
Authors: Kampfrath T , Bethoney S , Snyder J , Zhang J , Butterfield R 
Published: October 2024

Abstract

Background
Cardiac troponin I (cTnI) is the only troponin isoform present in the myocardium, where it binds to actin and inhibits actin and myosin interaction. Upon myocardial injury, cTnI is released into circulation and serial measurements can be used to aid in the diagnosis of acute myocardial infarction (AMI). In addition, in patients presenting with signs and symptoms of acute coronary syndrome (ACS), elevated cTnI levels provide useful prognostic information relative to short and long-term risk of all-cause mortality (ACM) and major adverse cardiac events (MACE). The objective of this study was to evaluate the clinical performance of the Atellica® IM TNIH assay to aid in risk stratification for ACM/MACE*.

Methods
Patients from 29 emergency departments (ED) across the United States presenting with signs and symptoms suggestive of ACS were followed for 30-, 90-, and 365-day progression to ACM/MACE (consisting of myocardial infarction, urgent revascularization, cardiac death, or heart failure hospitalization). At each timepoint, the risk (cumulative incidence) and hazard ratios were calculated for populations with baseline cTnI levels ≤ or &gt; the 99th percentile value. Kaplan-Meier curves were generated to display the absolute risk (cumulative incidence) of ACM/MACE outcomes. Analyses were performed for all enrolled patients (entire population) and separately for the entire population excluding those with an adjudicated AMI at presentation. Analyses were performed separately for both serum and plasma (lithium heparin) sample types.

Results
For the Entire Population cohort, the binary baseline TNIH result (TNIH &gt; overall 99th percentile or ≤ overall 99th percentile) was significantly associated with 30-, 90-, and 365-day cumulative ACM/MACE (p-value&lt;0.0125) for both plasma and serum samples. For plasma samples, risk difference increased from 6.27% at day 30 to 19.62% at day 365. For serum samples, risk difference increased from 6.24% at day 30 to 18.71% at day 365. Cox proportional hazard regression analysis compared the TNIH 99th percentile groups in their hazard of experiencing an ACM/MACE event in the 30-, 90-, and 365-days post ED presentation. For plasma samples, the hazard of ACM/MACE for subjects with cTnI values above the TNIH 99th percentile was relatively constant at each follow-up interval as more than double the rate of subjects below the 99th percentile; hazard ratios ranged between 2.81 (p-value&lt;0.0001) and 3.49-fold (p-value&lt;0.0001) for the three follow up visits. For serum samples, the hazard ratios were between 2.69 (p-value&lt;0.0001) and 3.28-fold (p-value&lt;0.0001) for the three follow up visits. Similar results were obtained for the Entire Population Excluding Subjects with Adjudicated AMI During Initial Presentation cohort.

Conclusions
The Atellica IM TNIH assay can be used in the detection of myocardial injury and can aid in risk stratification for 30-, 90-, and 365-day all-cause mortality (ACM) and major adverse cardiac events (MACE) in patients presenting with signs and symptoms suggestive of acute coronary syndrome (ACS). *This prognostic claim is not available in the United States.