BACKGROUND: High-sensitivity cardiac troponin (hs-cTnI) assays can quantify troponin concentrations with low limits of detection, potentially expediting and enhancing myocardial infarction diagnoses. This study investigates the real-world impact of hs-cTnI implementation on operational metrics and downstream cardiac services in patients presenting to the emergency department with chest pain. METHODS AND RESULTS: We conducted a retrospective study of patients who presented to 3 emergency departments for chest pain and in whom ≥1 troponin concentration was measured. We compared outcomes from January 2021 to March 2022 (conventional cardiac troponin I [cTnI]) against outcomes from April 2022 to March 2023 (post-hs-cTnI implementation). The primary outcome was hospital length of stay. The study included 32 076 emergency department patient-visits (17 267 with cTnI, 14 809 with hs-cTnI). Implementation of hs-cTnI was associated with shorter median total length of stay (6.6 versus 6.0 hours, CONCLUSION: Implementation of the hs-cTnI assay was associated with reduced hospital admissions, shorter length of stay, and decreases in most downstream cardiac testing.