A-020 Reassessing high-sensitivity cardiac troponin baseline cutoff for early rule-in of acute myocardial infarction in the emergency department

Abstract Background Chest pain is a leading cause of emergency department (ED) visits, necessitating rapid evaluation to rule-out and rule-in acute myocardial infarction (AMI). High-sensitivity cardiac troponin (hs-cTn) has emerged as the preferred biomarker for AMI diagnosis. Diagnostic algorithms utilizing baseline hs-cTn values and delta changes from serial measurements have been developed for rapid diagnosis of AMI. While most rapid algorithms focus on triaging (rule-out) non-AMI patients, the optimal baseline value to be used for early rule-in is evolving. Inappropriate rule-in of non-AMI patients can lead to unnecessary resource utilization, and ED overcrowding. We have implemented 52ng/L as the baseline abnormal cutoff in the care pathways for both hs-cTnT and hs-cTnI assays. In the current study, we have evaluated the performance of this and other new cutoffs for rapid AMI rule-in of among ED chest pain patients. Methods In this study, we measured hs-cTnT and hs-cTnI levels concurrently in ED patients presenting with chest pain. Diagnostic accuracy was assessed through sensitivity, specificity, negative and positive likelihood ratios, and predictive values at various cutoff points for AMI rule-in. Receiver operating characteristic (ROC) analysis was utilized to calculate the area under the curve (AUC) and determine the optimal baseline “rule-in/abnormal” threshold for both hs-cTn assays. Statistical analyses were conducted using Graphpad Prism 9, with statistical significance defined as p<0.05. Results In a cohort of 699 ED patients presenting with chest pain, comprehensive clinical assessment and final diagnosis identified 18 AMI cases and 681 non-AMI cases (true negative). In 17/18 confirmed AMI cases, baseline hs-cTn test results significantly exceeded the current abnormal (52 ng/L) cutoff. Among non-AMI patients, 136 had elevated hs-cTnT and 88 had elevated hs-cTnI baseline results above 52 ng/L. ROC analysis suggested optimal early AMI rule-in cutoffs of 82 ng/L for hs-cTnT and 122 ng/L for hs-cTnI. Primary and secondary cardiovascular events over 30-day, 90-day, and 1-year follow-up periods showed the effectiveness of these optimized cutoff values. Conclusion Our preliminary findings indicate that raising the baseline early rule-in abnormal cutoff from 52 ng/L to 82ng/L for hs-cTnT, and 122ng/L for hs-cTnI will enhance the specificity without compromising the sensitivity of the assays. This refinement has the potential to streamline patient triage, reduce unnecessary resource utilization, and help alleviate ED overcrowding Further studies involving larger populations are warranted to assess the applicability of these revised hs-cTn rule-in thresholds for AMI.