Background Protocols incorporating high-sensitivity troponin to guide decision making in the disposition of patients with suspected acute coronary syndromes (ACS) in the emergency department have received a lot of attention. Traditionally, patients with chest pain have required long periods of observation in emergency department before being deemed safe for discharge. In an era of limited health service resources, a protocol that could discharge patients safely within an hour of presentation is extremely attractive. Unfortunately, despite incorporation into some guidelines, these protocols have not been subjected to randomized comparisons evaluating safety, effectiveness, and cost-effectiveness. Objective This study is designed to provide the evidence required to allow key decision makers to implement these protocols: specifically, to provide evidence that a decision rule based on 0- and 1-hour high-sensitivity troponin T (hs-TnT) is safe, provides noninferior outcomes in all patients with suspected ACS, and that implementation of a rapid troponin protocol leads to efficient care. Design This prospective pragmatic trial (n = 5,400, 5 hospitals) randomly allocates patients with suspected ACS to either a 0/1-hour hs-TnT protocol as advocated in clinical guidelines, versus usual care of standard troponin reporting evaluated at 3 and 6 hours. The primary effectiveness composite end points of this study are all-cause death and new/recurrent ACS within 30 days. To evaluate cost-effectiveness, follow-up will determine clinical events, quality of life, and resource utilization within 12 months. Summary Demonstrating that a 0/1-hour hs-TnT protocol improves the effectiveness and efficiency of care within a robust comparative study will fill an evidence gap that currently limits the translation of more precise hs-TnT testing into better patient and health service outcomes.