This guidance considers high‑sensitivity troponin tests to be those that have a coefficient of variation of 10% or less at the 99th percentile (the upper limit of the reference population), and are able to detect cardiac troponin in at least 50% of the reference population. These recommendations refer to the use of these tests with early rule‑out protocols.
NICE is aware that there is a wide range of non‑high‑sensitivity troponin tests available to the NHS which are used to rule‑out non‑ST‑segment‑elevation myocardial infarction (NSTEMI). The evidence for these tests has not been assessed in this guidance, and the recommendations, therefore, do not relate to the use of non‑high‑sensitivity troponin tests.
1.1 The Elecsys Troponin T high‑sensitive assay and ARCHITECT STAT High Sensitive Troponin‑I assay are recommended as options for the early rule out of non‑ST‑segment‑elevation myocardial infarction (NSTEMI) in people presenting to an emergency department with chest pain and suspected acute coronary syndrome.
1.2 The assays are recommended for use with 'early rule‑out protocols', which typically include a blood sample for cardiac troponin I or T taken at initial assessment in an emergency department and a second blood sample taken after 3 hours. Laboratories should report absolute values and the upper reference limit should be set at the 99th percentile. Results should be interpreted along with clinical judgement and the results of clinical assessment. Healthcare professionals should take into account the pre‑test probability of NSTEMI, the length of time since the suspected acute coronary syndrome, the possibility of chronically elevated troponin levels in some patients and that 99th percentile thresholds for troponin I and T may differ between sexes. When NSTEMI is not ruled out using an 'early rule‑out protocol', further clinical assessment is required to determine whether a diagnosis of NSTEMI is appropriate.
1.3 The AccuTnI+3 assay is only recommended for use in clinical research, for early rule out of NSTEMI in people presenting to an emergency department with chest pain and suspected acute coronary syndrome (see section 7.1).
1.4 Healthcare professionals using 'early rule‑out protocols' including the Elecsys Troponin T high‑sensitive or the ARCHITECT STAT High Sensitive Troponin‑I assays should collect further information on the time taken to rule out NSTEMI in clinical practice and on the clinical outcomes of people presenting to an emergency department with chest pain and suspected acute coronary syndrome (see section 7.2).