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Picture the scene…

You are working on the Majors side of the (very busy) ED when a nurse approaches you with an ECG. “This chap has had an episode of chest pain – what do you think?…”

Learning Objective

To learn about the pathophysiology, clinical presentation, investigation and treatment of Acute Coronary Syndrome (ACS)

Read this comprehensive blog post from RCEM Learning. Focus particularly on the clinical assessment. Likelihood ratios are an excellent way of knowing how good a test is (when applied to a pretest probability). The higher the number the more likely a positive test is true and vice versa.

We use High Sensitivity Troponin as a test to “rule out” ACS as a diagnosis. Listen to St Emlyn’s Rick Body on this podcast explain what troponin is and how we can use it in the ED.

This part of the teaching session should be lead by an experienced clinican. The cases provided are merely examples and if possible the learners should be encouraged to discuss patients they have seen in their clinical practice.

A 50 year old man presents to the ED with sudden onset chest pain. The paramedics tells you he smokes 20 cigarettes a day and is on treatment for high blood pressure. The pain radiates into his right arm and up into his throat.

1, What other questions would you ask in the first few minutes of your clinical assessment?

The most important first decision is – is this patient having an ST Elevation Myocardial Infarction (STEMI). Make sure that an ECG is happening urgently, whilst you ask a few closed questions about the pain. When did it start? What were you doing when it started? Have you ever had a heart attack before? Do you still have pain now?

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2, An ECG is performed. What does it show?

The ECG shows widespread ST elevation throughout the chest leads, with “reciprocal change” in the the inferior leads.

3, What treatment would you give and what needs to happen next?

This patient needs urgent intervention for his likely ST elevation myocardial infarction. In this situation the role of the Emergency Physician is to “make things happen”. Give the patient a loading dose of aspirin and call you cardiology service (whatever form that may take – in my hospital that is the “ACS Nurse”). Make sure their pain is controlled with morphine and GTN 9if their blood pressure will tolerate it).

A 35 year old man presents with an intermittant history of central chest pain. It does not radiate and can come on at any time. He smokes occasionally and his mother and father are still alive and both have high blood pressure.

You need to ask similar questions to this patient as you did in case 1. Although his age makes him much less likely to being having ACS it is not impossible. It is particularly important to ask about family history (a first degree relative with cardiac disease under the age of 60) and illicit drug use – especially cocaine.

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Analysing this ECG in a methodical way, rate, rhythm, axis, PR segment, QRS segment and T wave, it appears to be normal sinus rhythm with no ischaemic changes.

It seems unlikely that this patient has acute coronary syndrome, but as this is a potentially life changing diagnosis we want to be as sure as we can be. He has a few risk factors and certainly isn’t “no risk”. In his case troponin testing will be really useful. In some centres a single high sensitivity troponin below the “limit of detection” with a normal ECG​1,2​ would be enough to rule out ACS, and in others it may be a pair of high sensitivity troponins to look at both the absolute values and to check there isn’t a significant rise or fall.

It’s also really important to remember to think about what is causing the pain, not just ruling out ACS.

In this session we have learned about the clinical assessment of the patient with acute coronary syndrome and the use of troponin to rule out a cardiac cause for chest pain.

Patients presenting to the Emergency Department with Acute Coronary Syndrome are not uncommon. The key things for the Emergency Physician to do are:

  • Concentrate on the history – this is the most important part. Do not be reassured by a lack of “risk factors”.
  • Get an ECG and look at it carefully. Practice your ECG interpretation.
  • If you are worried at all ask a senior. If the pain is characteristic of cardiac pain or the EGC shows ischaemic changes make things happen so that the patient is considered for cardiac catheterisation as soon as possible.

Consider these questions based on your learning today

Perhaps rather surprisingly the answer is (b)​3​ – pain radiating down the right arm. All of these features can be associated with ACS, but in the paper​3​ quoted the LR+ for right arm is 4.7.

The correct answer is (c). All muscle will release troponin if damaged, but it is the cardiac troponin that we are measuring in the diagnosis of ACS. Although often rasied in patients with renal faiulre (due to accumulation) the troponin will still go up in these patients if they have myocardial damage. Troponin will take some time to rise after myocardial damage, and “unstable angina” has often been considered a “troponin negative” state.

In order to embed today’s learning further, reflect on what you have learnt and record in your portfolio whether it has had any impact (or is expected to have any impact) on your performance and practice.

Was this a topic that you were confident you knew already? Which parts were new to you? Were there elements that you will use on your next clinical shift.

Dscuss this session with your colleagues – were there people who missed it who you can share the highlights with?

References and Further Reading

  1. 1.
    Beardsell I. JC: Are we fully Loded? St Emlyn’s. Published May 13, 2020. Accessed June 9, 2020.
  2. 2.
    Carlton EW, Ingram J, Taylor H, et al. Limit of detection of troponin discharge strategy versus usual care: randomised controlled trial. Heart. Published online May 5, 2020:heartjnl-2020-316692. doi:10.1136/heartjnl-2020-316692
  3. 3.
    Body R, Carley S, Wibberley C, McDowell G, Ferguson J, Mackway-Jones K. The value of symptoms and signs in the emergent diagnosis of acute coronary syndromes. Resuscitation. Published online March 2010:281-286. doi:10.1016/j.resuscitation.2009.11.014