Cardiac Markers

Immunoassay parameters are provided in the following programmes: Endocrine, Haematinics, Cardiac Markers, BNP and NT-ProBNP.

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 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 hsTroponin 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 Cardiac markers EQA programme is available as serum or plasma based samples, participants can select the programme most appropriate for their analyser. Four liquid human serum samples are distributed monthly, with a minimum of 48 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 threshold or limit of detection and samples at the 99^th centile thresholds for hs Troponin. The programme also accommodates Point of care (POCT) Troponin assays as well as those offering semi-quantitative reporting of Troponin. They are distributed on a number of occasions over the year which allows for the assessment of the organisation’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 TnT and Tnl.
Allows semi-quantitative reporting for PoCT Tn.
Liquid human serum samples require no pre-analytical preparation.
Linearly related panel covering a clinically relevant range.

Frequency:
Monthly

Samples:
4 x 1.0mL

Material:
Off the clot human serum

Cardiac Markers Programme
Analyte	Approx. Range Covered
hsTroponin I	1-1250	ng/L (Abbott Architect/ Alinity)
hsTroponin T	4-440	ng/L (Roche Elecsys)
Troponin T	<10-380	ng/L (AQT 90)
Troponin I	<10-1375	ng/L (iStat)
CK MB (activity)	0-180	IU/L (Vitros)
*CK MB (mass)	0-60	µg/L
*Myoglobin	14-500	µg/L