BACKGROUND: We examined the diagnostic performance of high-sensitivity cardiac troponin I (hs-cTnI) vs contemporary cTnI with use of the 99th percentile alone and with a normal electrocardiogram (ECG) to rule out acute myocardial infarction (MI) and serial changes (deltas) to rule in MI. METHODS: We included consecutive patients presenting to a US emergency department with serial cTnI on clinical indication. Diagnostic performance for acute MI, including MI subtypes, and 30-day outcomes were examined. RESULTS: Among 1631 patients, MI was diagnosed in 12.9% using the contemporary cTnI assay and in 10.4% using the hs-cTnI assay. For ruling out MI, contemporary cTnI≤99th percentile at 0, 3, and 6 h and a normal ECG had a negative predictive value (NPV) of 99.5% (95% CI, 98.6 -100) and a sensitivity of 99.1% (95% CI, 97.4 -100) for diagnostic and safety outcomes. Serial hscTnI measurements ≤99th percentile at 0 and 3 h and a normal ECG had an NPV and sensitivity of 100% (95% CI, 100-100) for diagnostic and safety outcomes. For ruling in MI, contemporary cTnI measurements had specificities of 84.4% (95% CI, 82.5- 86.3) at presentation and 78.7% (95% CI, 75.4-82.0) with serial testing at 0, 3, and 6 h, improving to 89.2% (95% CI, 87.1- 91.3) by using serial cTnI changes (delta, 0 and 6 h) >150%. hs-cTnI had specificities of 86.9% (95% CI, 85.1- 88.6) at presentation and 85.7% (95% CI, 83.5- 87.9) with serial testing at 0 and 3 h, improving to 89.3% (95% CI, 87.3-91.2) using a delta hs-cTnI (0 and 3 h) >5 ng/L. CONCLUSIONS: hs-cTnI and contemporary cTnI assays are excellent in ruling out MI following recommendations predicated on serial testing and the 99th percentile with a normal ECG. For ruling in MI, deltas improve the specificity.
Bibliographical noteFunding Information:
Employment or Leadership: F.S. Apple, HyTest Ltd. and Clinical Chemistry, AACC. Consultant or Advisory Role: Y. Sandoval, Roche Diagnostics; S.W. Smith, Alere, Roche Clinical Diagnostics, Siemens; F.S. Apple, Philips Healthcare Incubator, Metanomics Healthcare. Stock Ownership: None declared. Honoraria: F.S. Apple, Instrumentation Laboratory, Abbott POC. Research Funding: UTROPIA study (NCT02060760) partially funded through a grant from Abbott Diagnostics and the Minneapolis Medical Research Foundation. S.A. Love, Research PI through Minneapolis Medical Research Foundation (MMRF), not salaried, and Biokit, Hytest Ltd., Instrumentation Laboratory; F.S. Apple, Re- search PI through Minneapolis Medical Research Foundation (MMRF), not salaried: Abbott Diagnostics, Roche Diagnostics, Siemens Healthcare, Alere, Ortho-Clinical Diagnostics, Nanomix, Becton Dickinson, Singulex. Expert Testimony: None declared.
© 2017 American Association for Clinical Chemistry.