Comparing High-Sensitivity Troponin 0/1, 0/2, and 0/3 Hour Retesting Algorithms

Background: Each emergency department (ED) patient with suspected acute coronary syndrome (ACS) receives an initial high-sensitivity troponin test to rule out myocardial infarction (MI).This single test results in many false positives, necessitating repeat testing to further exclude MIs and avoid unnecessary, invasive, and costly workups.Each method of retesting is a time-specific and time-constrained algorithm, requiring different maximum changes in troponin for rule out.This targeted literature review compares the most common algorithms: 0/1, 0/2, and 0/3 hours.Methods: A literature search was conducted in June 2025 in PubMed and SCOPUS using key terms "high-sensitivity troponin" and "algorithm."Studies published from 2015 onward were screened for relevance, clinical focus, comparison of retesting algorithms, diagnostic performance and clinical outcomes.Thirty articles were reviewed. Results:The literature contains repeated validations of all three retesting algorithms, primarily in non-US hospitals.However, studies show that a 0/3 hour pathway is statistically less effective and it is no longer recommended.Shorter pathways, such as the 0/1 hour, reduce length of stay (LOS) in the ED.Studies suggest that 0/2 hour testing is equally effective for risk stratification in a more clinically feasible manner while eliminating analytical variability. Conclusion:Further research is needed to determine the safety, efficiency and feasibility of the 0/2 hour retesting algorithm in US hospital settings.Despite the 0/1 hour algorithm's effectiveness, there is concern it is clinically impractical to retest within such a short time window.