High-sensitivity troponin i: One-hour evaluation for acute myocardial infarction in the United States

Background: High sensitivity cardiac troponin I (hs-cTnI) assays are currently being approved for use in the United States (US). Our objective was to determine the efficacy of a 1 hour acute myocardial infarction (AMI) rule-out/rule-in European derived hs-cTnI algorithm when applied to US Emergency patients in the High Sensitivity Cardiac Troponin I in the US (HIGH-US) study. \u3c Methods: Adults presenting with any suspicion by the treating emergency physician for AMI were included. Patients with STEMI were excluded. Baseline and1 hour plasma samples were analyzed in a core laboratory (University of Maryland) using the Siemens Atellica hs-cTnI assay (99th % 45.0 ng/L). AMI diagnosis was independently adjudicated using all 30 day clinical materials available. Results: 2505 patients were enrolled in 29 US medical centers with 2113 having complete data for the 1 hour algorithm analyses. Subjects had a mean age of 56.7 ±12.9 years and 1419 (56.5%) were males. Past medical history included hypertension in 1730 (69.1%), coronary artery disease, cardiac bypass surgery, percutaneous coronary interventions or AMI in 930 (37.1%) and diabetes in 739 (29.5%) while 83 (3.3%) were receiving renal dialysis. ECG abnormalities included ST depression (≥ 0.5) or elevation (\u3e 1.0) in 231 (9.2%) or T wave inversions in 298 (11.9%). Patients with AMI (except those on dialysis) had significantly more (p \u3c 0.001) of these clinical characteristics but they were also commonly seen in those without AMI. 1065 (50.4%) were ruled-out with a NPV 99.7% and sensitivity 98.7% (95%CI: 99.2-99.9 and 96.3-99.6 respectively). Of these 714 (33.8%) had a baseline hs-cTnI value \u3c 3 ng/ml and 351 (16.6%) had a baseline value \u3e 6 ng/L and a delta 1 hour value \u3c 3 ng/L. 265 (12.6%) were ruled-in with a PPV 69.4% and specificity 95.7% (95%CI: 63.6-74.7 and 94.7-96.5 respectively). Of these 210 (9.9%) had a baseline hs-cTnI ≥ 120 ng/L and 55 (2.5%) had a delta 1 hour value ≥ 12 ng/L. The remaining 783 (37.1%) in the continue evaluation zone had a prevalence of adjudicated AMI of 5.6% (95%CI 4.2-7.5). Conclusion: The European utilized 1 hour rule-out/rule-in algorithm using hs-cTnI for AMI evaluation yields very similar results for rule-out (very high NPV) when used in an all comers US population having many clinical cardiac risk factors. Further studies are needed to improve the PPV and specificity of a 1 hour rule-in algorithm for AMI for use in the US ED population