Revisiting High-Sensitivity Cardiac Troponin Abnormal Baseline Cutoffs: Implications for AMI Diagnosis in the Emergency Department

<b>Background</b>: Current clinical guidelines recommend 52 ng/L as the abnormal baseline cutoff in high-sensitivity cardiac troponin (hs-cTn) algorithms for the rapid diagnosis of acute myocardial infarction (AMI). Though abnormal, this threshold is not AMI-specific, leading to extensive workups for many non-AMI chest pain patients, overutilization of resources, and emergency department (ED) overcrowding. Hence, the performance of this baseline abnormal cutoff was compared against the refined new thresholds for rapid AMI diagnosis in ED chest pain patients. <b>Methods</b>: We included ED chest pain patients with hs-cTnT and hs-cTnI levels simultaneously measured and clinical outcomes adjudicated by cardiologists. We performed receiver operating characteristics (ROC) analyses across various thresholds for diagnostic performance, including sensitivity, specificity, negative and positive likelihood ratios, and predictive values. Statistical analysis was carried out using Graphpad Prism 10, with <i>p</i> < 0.05 considered as significant. <b>Results</b>: In our study, 17 patients were adjudicated as AMI, and 682 patients were ruled out for AMI. In 15/17 AMI cases, baseline hs-cTn values far exceeded 52 ng/L. Notably, among non-AMI individuals, 140 (hs-cTnT) and 91 (hs-cTnI) also exceeded this cutoff. ROC analyses identified optimal abnormal cutoffs of 82 ng/L for hs-cTnT and 122 ng/L for hs-cTnI, which improved specificity without compromising sensitivity. Post-discharge follow-up at 1, 3, and 12 months for cardiovascular events supported these revised thresholds. <b>Conclusions</b>: Increasing the baseline abnormal value from 52 ng/L to 82 ng/L for hs-cTnT and to 122 ng/L for hs-cTnI in care pathways could reduce false positives with the potential to decrease unnecessary testing and alleviate long stays in the ED and resource management. Larger, diverse cohort studies are warranted to validate these findings.