Overview of the implementation process

Step 1: Stakeholder engagement

Establish a project team

A local project team will be able to work together to develop the implementation process and manage the changes to practice needed. This could be an established chest pain working group with experience in implementing other pathways and protocols or a newly formed group.

Identify the project leads:

A clinical project champion. Someone with an interest and enthusiasm to learn more about using high-sensitivity troponin assays for early rule out of NSTEMI and who is familiar with the relevant guidance and evidence.
Project lead or manager who will be accountable for delivery.
Project or management sponsor who will be able to help assess the financial viability of the project, ensure a business case is produced and help to show the potential cost savings.

Project team members are likely to include:

cardiologists
chest pain nurse specialists
emergency department doctors and senior nurses
clinical biochemists
doctors from the acute medical team.

Wider engagement of stakeholders

In addition to the stakeholder groups already represented on the local project team, engagement and agreement on the planned changes should be sought from:

clinical directors
healthcare professionals working in the emergency department, acute medical units, cardiology and hospital laboratories
directorate operational and finance management
pharmacists
commissioners.

Use for example: meetings, presentations and sharing copies of protocols, to secure support by communicating the benefits and reasons for adoption.

Step 2: Assessment of readiness

Questions the project team should consider when building the case for adoption and developing the implementation process are:

Current demand

How many people present to the emergency department with chest pain suspected to be caused by an acute coronary syndrome?
What percentage are discharged following rule out of NSTEMI and what is their length of stay?
How many people is the technology suitable for (consider selection criteria, contraindications)?

Laboratory

Does the hospital laboratory have access to high-sensitivity troponin assays with the current service contract in place?
Which manufacturer currently provides the biochemistry platforms? Do they offer NICE-recommended high-sensitivity troponin assays?
When will the hospital laboratory be tendering for new equipment?

Care pathway mapping

What is the current care pathway? What actually happens? Where do people wait for troponin results? Who is involved (decision making, doing tasks)?
What are the current follow-up care and onward referral arrangements?
What is the potential effect on other specialities, for example medical admissions and cardiology, of adopting early rule-out protocols for NSTEMI using high-sensitivity troponin assays?
Do we know of any other sites who have done this or are planning it? How do we learn from them? Can we coordinate adoption with any local sites?

Cost

What are the anticipated costs and savings from adoption?
Is a business case needed and who is best placed to support this at a senior level and help overcome any financial barriers?

Measuring impact

What data do we currently collect for people presenting with chest pain suspected to be caused by an acute coronary syndrome?
Who is currently responsible for collecting these data?

Step 3: Develop a communications strategy

There may be uncertainty among stakeholders about the diagnostic accuracy of ruling out NSTEMI in a shorter time than before. There may also be concerns that using a higher-sensitivity cardiac troponin assay will increase workload because of inappropriate testing and inaccurate interpretation. It is important to share the potential benefits with stakeholders using methods tailored approaches:

Depending on current local pathways, there could be fewer admissions for people with chest pain suspected to be caused by an acute coronary syndrome who are waiting for troponin results. It is estimated that following adoption, between a quarter and a third of people who would have previously been admitted can be discharged.
There could be a shorter stay in the emergency department for people when an acute myocardial infarction is ruled out.
There would be more appropriate referrals and onward follow up from the emergency department to other services such as the rapid access chest pain clinic.
There would be more rapid identification of NSTEMI, leading to quicker decisions on the next steps in the person's care.
There could be fewer referrals to cardiology from the emergency department for people with chest pain suspected to be caused by an acute coronary syndrome. Note there may be an increase in referrals for people who need further investigation and treatment.

Step 4: Procurement and set up of the preferred test

NICE recommends the following high-sensitivity troponin tests (for use with an early-rule out test strategy) as options to rule out non-ST-segment elevation myocardial infarction (NSTEMI) in people presenting to an emergency department with chest pain and suspected acute coronary syndrome:

Access High-Sensitivity Troponin I Assay
ADVIA Centaur High-Sensitivity Cardiac Troponin-I Assay
Alinity High Sensitive Troponin-I assay
ARCHITECT STAT High Sensitive Troponin-I assay
Atellica IM High-Sensitivity Cardiac Troponin I Assay
Dimension Vista High-Sensitivity Cardiac Troponin I Assay
Dimension EXL High-Sensitivity Cardiac Troponin I Assay
Elecsys Troponin T-high sensitive assay
Elecsys Troponin T-high sensitive STAT assay
VIDAS High sensitive Troponin I assay
VITROS High Sensitivity Troponin I Assay.

The International Federation of Clinical Chemistry and Laboratory Medicine committee on clinical applications of cardiac bio-markers has produced a high sensitivity cardiac troponin I and T assay analytical characteristics document for all assays claimed by manufacturers to be high sensitivity.

Laboratories without access to these NICE-recommended high-sensitivity cardiac troponin assays through their managed service contract should ask their provider if there is scope to access these tests. Some contracts may state that when a test is clinically needed it can be sourced from another provider. Service contracts are renewed regularly, therefore this could be a consideration in the tendering process for a new contract.

Laboratories should adhere to their usual quality assurance and validation processes when adopting high-sensitivity cardiac troponin assays in line with the UK accreditation service (UKAS), which includes checking if there are differences in results from all their platforms used to run the high-sensitivity cardiac troponin assays.

Before adoption, laboratories should validate the assay at different values including the rule-out cut off. This is particularly important because the sensitivity of the assay means that only small changes influence clinical actions. Findings should be used to inform the cut-off values and thresholds for developing the clinical protocol and give reassurance and confidence to stakeholders about the benefits of adoption.

If an assay can be used for serum and plasma samples, it is suggested that the same sample type should be used when serially testing samples from the same patient. Ongoing internal quality assurance will be required in line with UKAS. Sites should be signed up to a UKAS-accredited external quality assessment scheme. Quality assurance checks should be done at or near clinical decision points. This is commonly at the limit of detection and 99th percentile, as a minimum.

Sourcing internal quality assurance samples with a low concentration of troponin can be challenging because producing such samples, at scale, can be technically difficult. Suggested solutions include developing samples in house and identifying third-party providers who can offer this. As with all internal quality assurance materials, sites will need to purchase the samples. Because of the difficulty in getting low concentration samples this can be an additional cost for some laboratories compared with other assays.

It is important for everyone involved to know which assay is being used and the specific pathway that is being followed, because the cut offs for different assays are not interchangeable.

Step 5: Agree an early rule-out clinical protocol

There is no nationally recommended protocol with thresholds and cut-off values for early rule out of NSTEMI using high-sensitivity cardiac troponin assays in England. For people presenting to an emergency department with chest pain and suspected acute coronary syndrome, the NICE diagnostics guidance on early rule out of NSTEMI using high-sensitivity troponin assays recommends the specified high-sensitivity troponin tests 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.

In the section on people presenting with acute chest pain in NICE's guideline on chest pain of recent onset there is also a recommendation for people at low risk of MI (as indicated by a validated tool), which says to consider performing a single high-sensitivity troponin test only at presentation to rule out NSTEMI if the first troponin test is below the lower limit of detection (negative).

The European Society of Cardiology guidelines on the management of acute coronary syndromes (2020) discuss 3 different rapid rule out algorithms; 0 hour / 1 hour algorithm (0 hour and 1 hour refer to the time in hours from the first blood test), a 0 hour / 2 hour algorithm and a 0 hour / 3 hour algorithm.

Sites should use relevant guidance including the European Society of Cardiology's guidelines on the fourth universal definition of myocardial infarction, in addition to their own validation testing to agree a local protocol. Considerations should include:

Whether nanograms/litre will be used as the unit of measure for reporting, as recommended by expert opinion.
Whether the upper reference limit should be set at the 99th percentile and if this will be used to support decision making in the early rule-out pathway.
Whether the limit of detection will be used to support decision making in the pathway.
What evidence-based high-sensitivity cardiac troponin assay result is acceptable for discharge (assuming there are no other reasons for admission).
For multiple test strategies, what change in troponin values between the 2 tests should warrant further investigation or no further action (a rise or fall in troponin levels can indicate cardiac muscle damage).
Whether results will be reported in whole numbers or to 1 decimal place. How this will affect patient care if the result is near a threshold or a change in troponin is detected.
What risk stratification tools will be used and how the results will influence the high-sensitivity cardiac troponin testing strategy.
How the time since pain onset will affect the testing strategy used.
Whether the protocol still allows and encourages clinical judgement (chest pain management cannot be entirely protocol driven).

It is important to note that the limit of detection will vary between manufacturers. Also, the 99th percentile thresholds for troponin I and T will differ between manufacturers and may differ between sexes (See section 4.7 of the NICE diagnostics guidance).

Sites reported using a small implementation team or a specialist subgroup initially to develop and agree a local protocol and then sought wider agreement from stakeholders.

If trusts can work together to agree a protocol across a locality or region this will make treatment more consistent. The Liverpool acute chest pain care pathway is an example of this.

Step 6: Training

Staff training, education and awareness raising is crucial to ensure that the benefits of high-sensitivity cardiac troponin assays for early rule out of NSTEMI are optimised. Education efforts should target emergency department, acute medicine, cardiology and laboratory staff. Outreach can take the form of presentations at team meetings, junior doctor inductions, study days, training sessions, and targeted emailing to staff.

Training at the point of implementation and regular ongoing updates should include:

Patient selection: The person responsible for deciding who the test should be requested for should be skilled in patient selection to minimise the risk of inappropriate requests.
Blood-taking techniques: Haemolysed samples give false high-sensitivity cardiac troponin results. This could cause delays. Blood collection tube manufacturers may be able to support this training.
Interpretation: High-sensitivity cardiac troponin results are interpreted differently from non-high-sensitivity cardiac troponin results. They should not be interpreted and acted on in isolation but after a holistic clinical assessment.

Step 7: Adoption into practice

To realise the benefits of using high-sensitivity cardiac troponin assays for early rule out of NSTEMI, sites will need a change in service delivery to integrate the early rule-out protocol into current hospital systems. Consider:

Whether any new documentation is needed (protocols, flow charts, referral forms).
Identifying who will be responsible for requesting the high-sensitivity cardiac troponin assay. Usually this is the emergency department and acute medicine doctors and nurse practitioners.
Ensuring the assays are done only when appropriate.
Ensuring the initial blood sample is taken as soon as the protocol indicates.
Ensuring there is capacity for people to wait in an appropriate allocated location for the results and for a second blood sample to be taken (if needed), ideally avoiding a formal admission to the hospital. Can an ambulatory care environment be used with chairs rather than beds?
If a second sample is needed, make sure it is taken as soon as it is due to prevent delays. This may be before the initial test results are available. Clear documentation and handover sheets can help.
Putting a system in place to ensure that relevant staff are aware of a result as soon as it is available. Delays at this stage are common.
Agreeing who will be responsible for decision making based on the results. This is usually senior doctors in the emergency department, cardiology or acute medicine. Some sites have recruited chest pain nurses who advise the emergency department on interpreting troponin results in complex situations.
Identifying how the testing protocol will affect patient flow and workload.
Establishing discharge and onward referral arrangements, which could include:
- when nurse-led discharge protocols could be used
- acute chest pain referral pathways to acute medicine for patients who meet certain criteria
- clear agreements with cardiology, including nurse specialists, about when to review patients if they meet certain criteria
- adaptation of the referral pathway for rapid access chest pain clinics to take patients who meet defined criteria.
Developing discharge information sheets for patients and their GPs, or ensuring enough information is added to the emergency department GP discharge letter, to clarify what tests have been done and what they mean. This could prevent workload associated with follow-up enquiries.
Identifying any changes needed in laboratory processes to achieve a turnaround time from the sample arriving in the laboratory to a result at 1 hour.

Step 8: Measurement

It is important to take measurements before, during and after adopting the technology to ensure implementation has been successful. The systems and processes for how data will be collected and reported must be agreed and someone given overall responsibility. Consider whether the data could be shared with regional and national data collection systems to support ongoing refinement of protocols.

Monitoring performance

These audit measures are suggested to monitor compliance with using local early rule out of NSTEMI protocols with high-sensitivity troponin assays:

High-sensitivity cardiac troponin assays are done in line with the local protocol.
Patients on a pathway for early rule out of NSTEMI are assessed for their risk of myocardial infarction (as indicated by a validated tool).
Patients have a sample taken to measure troponin within a locally agreed time period, in line with the timings recommended by the protocol.
Turnaround times in the laboratory from sample receipt (or sample collection if agreed locally) to availability of the result within 1 hour. This is in line with suggested key performance indicators from the Royal College of Pathologists linked to patient pathways and emergency department blood sciences turnaround times.

Measuring impact

There are several suggested measures which could assess impact:

For people with chest pain suspected to be caused by an acute coronary syndrome, time spent in the emergency department.
Transit times for people going through the emergency department on the acute coronary syndrome rule out pathway.
Incidence of readmission of people with troponin-positive acute coronary syndrome within 30 days following the low-risk rule-out pathway.
Admission rates for chest pain suspected to be caused by an acute coronary syndrome (suggested ICD10 code: R07) when the early rule-out protocol is in place.

High-sensitivity troponin tests for the early rule out of NSTEMI

Tools and resources

Adoption support resource – insights from the NHS