High-sensitivity Troponin

Purpose:
The Programme aims to assess the performance of organisations utilising biochemical cardiac markers to aid in the diagnosis of acute coronary syndrome (ACS) and cardiac ischaemia. High sensitivity cardiac Troponin (hs-cTn) T and I have replaced standard Troponin assays, myoglobin and Creatine kinase – MB as the preferred markers of myocardial injury. NICE diagnostic guidance – [DG40], High sensitivity troponin tests for the early rule out of NSTEMI, published in August 2020 recommended a number of hs-cTn methods that could be used 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.

NICE Guidance DG40 Recommendations

1.2 The tests are recommended for use with different early rule-out test strategies alongside clinical judgement, including:

A single sample on presentation using a threshold at or near the limit of detection, which will vary depending on the assay being used. If this sample is positive it should not be used to rule in NSTEMI.
Multiple sample strategies, which typically include a sample at initial assessment followed by a second sample taken at 30 minutes to 3 hours (if clinically appropriate) and use of 99th percentile thresholds or thresholds at or near the limit of detection of the assay. Healthcare professionals should consider the likely time since the onset of symptoms when interpreting test results.

1.3 When NSTEMI is not ruled out using early rule-out test strategies, use NICE’s guideline on recent -onset chest pain of suspected cardiac origin, [CG95] to help diagnose myocardial infarction, and consider using sex-specific thresholds at the 99th percentile (see section 4.7 and section 5.2).

Scope:
The Weqas hsTroponin EQA programme is available specifically for high sensitivity Troponin Assays. The programme covers both hsTroponin I and T and includes both serum and EDTA plasma samples. The serum samples are suitable for most hs-cTn methods, whilst EDTA plasma is recommended for use on the Quidel TriageTrue hsTroponin I method. A separate Cardiac Programme is available for all other standard Troponin methods including Point of Care (POCT Cardiac Programme).

Three liquid human samples are distributed monthly, with a minimum of 36 samples distributed over the year covering a wide clinical range. The samples consist of endogenous samples from patients along with a panel of linearly related samples produced from donations from healthy volunteers spiked with Cardiac Troponin.

The programme includes samples at clinically relevant ranges at or near the limit of detection, samples at the 99th centiles, thresholds for early rule out and at high hs-cTn concentrations seen in myocardial infarction. The samples are distributed on a number of occasions over the year which allows for the assessment of the laboratory’s and method’s performance, including linearity, bias, within and between batch imprecision.

Key Features:

Includes challenging samples at limits of detection and diagnostic “99^th centile” for hs-cTnT and hs-cTnl.
Liquid human serum samples require no pre-analytical preparation.
Linearly related panel covering a clinically relevant range.