Limited data exist on rapid risk-stratification strategies using the U.S. Food and Drug Administration-cleared high-sensitivity cardiac troponin I (hs-cTnI) assays. This study sought to examine single measurement hs-cTnI to identify patients at low and high risk for acute myocardial infarction (MI). This was a prospective, multicenter, observational study of patients with suspected acute MI enrolled across 29 U.S. sites with hs-cTnI measured using the Atellica IM TnIH and ADVIA Centaur TNIH (Siemens Healthineers) assays. To identify low-risk patients, sensitivities and negative predictive values (NPVs) for acute MI and MI or death at 30 days were examined across baseline hs-cTnI concentrations. To identify high-risk patients, positive predictive values and specificities for acute MI were evaluated. Among 2,212 patients, acute MI occurred in 12%. The limits of detection or quantitation resulted in excellent sensitivities (range 98.6% to 99.6%) and NPVs (range 99.5% to 99.8%) for acute MI or death at 30 days across both assays. An optimized threshold of <5 ng/l identified almost one-half of all patients as low risk, with sensitivities of 98.6% (95% confidence interval: 97.2% to 100%) and NPVs of 99.6% (95% confidence interval: 99.2% to 99.9%) for acute MI or death at 30 days across both assays. For high-risk patients, hs-cTnI ≥120 ng/l resulted in positive predictive values for acute MI of ≥70%. Recognizing the continuous relationship between baseline hs-cTnI and risk for adverse events, using 2 Food and Drug Administration-cleared hs-cTnI assays, an optimized threshold of <5 ng/l safely identified almost one-half of all patients as low risk at presentation, with hs-cTnI ≥120 ng/l identifying high-risk patients.