Recent-onset chest pain of suspected cardiac origin: assessment and diagnosis

This guideline covers assessing and diagnosing recent chest pain in people aged 18 and over and managing symptoms while a diagnosis is being made. It aims to improve outcomes by providing advice on tests (ECG, high-sensitivity troponin tests, multislice CT angiography, functional testing) that support healthcare professionals to make a speedy and accurate diagnosis.

# Recommendations
People have the right to be involved in discussions and make informed decisions about their care, as described in NICE's information on making decisions about your care.
Making decisions using NICE guidelines explains how we use words to show the strength (or certainty) of our recommendations, and has information about prescribing medicines (including off-label use), professional guidelines, standards and laws (including on consent and mental capacity), and safeguarding.

# Providing information for people with chest pain
Discuss any concerns people (and where appropriate their family or carer/advocate) may have, including anxiety when the cause of the chest pain is unknown. Correct any misinformation. 
Offer people a clear explanation of the possible causes of their symptoms and the uncertainties. 
Clearly explain the options to people at every stage of investigation. Make joint decisions with them and take account of their preferences:
Encourage people to ask questions.
Provide repeated opportunities for discussion.
Explain test results and the need for any further investigations. 
Provide information about any proposed investigations using everyday, jargon-free language. Include:
their purpose, benefits and any limitations of their diagnostic accuracy
duration
level of discomfort and invasiveness
risk of adverse events. 
Offer information about the risks of diagnostic testing, including any radiation exposure. 
Address any physical or learning difficulties, sight or hearing problems and difficulties with speaking or reading English, which may affect people's understanding of the information offered. 
Offer information after diagnosis as recommended in the relevant disease management guidelines:
NICE guideline on acute coronary syndromes
NICE guideline on stable angina
NICE guideline on generalised anxiety disorder and panic disorder in adults
NICE guideline on gastro-oesophageal reflux disease and dyspepsia in adults. 
Explain if the chest pain is non-cardiac and refer people for further investigation if appropriate. 
Provide individual advice to people about seeking medical help if they have further chest pain. 

# People presenting with acute chest pain
This section of the guideline covers the assessment and diagnosis of people with recent acute chest pain or discomfort, suspected to be caused by an acute coronary syndrome (ACS). The term ACS covers a range of conditions including unstable angina, STsegment-elevation myocardial infarction (STEMI) and nonSTsegment-elevation myocardial infarction (NSTEMI).
The guideline addresses assessment and diagnosis irrespective of setting, because people present in different ways. For early management of these conditions, follow the NICE guideline on acute coronary syndromes.

## Initial assessment and referral to hospital
Check immediately whether people currently have chest pain. If they are pain free, check when their last episode of pain was, particularly if they have had pain in the last 12 hours. 
Determine whether the chest pain may be cardiac and therefore whether this guideline is relevant, by considering:
the history of the chest pain
the presence of cardiovascular risk factors
history of ischaemic heart disease and any previous treatment
previous investigations for chest pain. 
Initially assess people for any of the following symptoms, which may indicate an ACS:
pain in the chest and/or other areas (for example, the arms, back or jaw) lasting longer than 15 minutes
chest pain associated with nausea and vomiting, marked sweating, breathlessness, or particularly a combination of these
chest pain associated with haemodynamic instability
new onset chest pain, or abrupt deterioration in previously stable angina, with recurrent chest pain occurring frequently and with little or no exertion, and with episodes often lasting longer than 15 minutes. 
Do not use people's response to glyceryl trinitrate (GTN) to make a diagnosis. 
Do not assess symptoms of an ACS differently in men and women. Not all people with an ACS present with central chest pain as the predominant feature. 
Do not assess symptoms of an ACS differently in ethnic groups. There are no major differences in symptoms of an ACS among different ethnic groups. 
Refer people to hospital as an emergency if an ACS is suspected (see recommendation 1.2.1.3) and:
they currently have chest pain or
they are currently pain free, but had chest pain in the last 12 hours, and a resting 12lead ECG is abnormal or not available. 
If an ACS is suspected (see recommendation 1.2.1.3) and there are no reasons for emergency referral, refer people for urgent same-day assessment if:
they had chest pain in the last 12 hours, but are now pain free with a normal resting 12lead ECG or
the last episode of pain was 12 to 72 hours ago. 
Refer people for assessment in hospital if an ACS is suspected (see recommendation 1.2.1.3) and:
the pain has resolved and
there are signs of complications such as pulmonary oedema.Use clinical judgement to decide whether referral should be as an emergency or urgent same-day assessment. 
If a recent ACS is suspected in people whose last episode of chest pain was more than 72 hours ago and who have no complications such as pulmonary oedema:
carry out a detailed clinical assessment (see recommendations 1.2.4.2 and 1.2.4.3)
confirm the diagnosis by resting 12lead ECG and blood troponin level
take into account the length of time since the suspected ACS when interpreting the troponin level.Use clinical judgement to decide whether referral is necessary and how urgent this should be. 
Refer people to hospital as an emergency if they have a recent (confirmed or suspected) ACS and develop further chest pain. 
When an ACS is suspected, start management immediately in the order appropriate to the circumstances (see the section on immediate management of a suspected acute coronary syndrome) and take a resting 12lead ECG (see the section on resting 12-lead ECG). Take the ECG as soon as possible, but do not delay transfer to hospital. 
If an ACS is not suspected, consider other causes of the chest pain, some of which may be life-threatening (see recommendations 1.2.6.5, 1.2.6.7 and 1.2.6.8). 

## Resting 12-lead ECG
Take a resting 12lead ECG as soon as possible. When people are referred, send the results to hospital before they arrive if possible. Recording and sending the ECG should not delay transfer to hospital. 
Follow local protocols for people with a resting 12lead ECG showing regional STsegment elevation or presumed new left bundle branch block (LBBB) consistent with an acute STEMI until a firm diagnosis is made. Continue to monitor (see recommendation 1.2.3.4). 
Follow the NICE guideline on acute coronary syndromes for people with a resting 12lead ECG showing regional STsegment depression or deep T wave inversion suggestive of a NSTEMI or unstable angina until a firm diagnosis is made. Continue to monitor (see recommendation 1.2.3.4). 
Even in the absence of STsegment changes, have an increased suspicion of an ACS if there are other changes in the resting 12lead ECG, specifically Q waves and T wave changes. Consider following the NICE guideline on acute coronary syndromes if these conditions are likely. Continue to monitor (see recommendation 1.2.3.4). 
Do not exclude an ACS when people have a normal resting 12lead ECG. 
If a diagnosis of ACS is in doubt, consider:
taking serial resting 12lead ECGs
reviewing previous resting 12lead ECGs
recording additional ECG leads.Use clinical judgement to decide how often this should be done. Note that the results may not be conclusive. 
Obtain a review of resting 12lead ECGs by a healthcare professional qualified to interpret them as well as taking into account automated interpretation. 
If clinical assessment (as described in recommendation 1.2.1.10) and a resting 12lead ECG make a diagnosis of ACS less likely, consider other acute conditions. First consider those that are life-threatening such as pulmonary embolism, aortic dissection or pneumonia. Continue to monitor (see recommendation 1.2.3.4). 

## Immediate management of a suspected acute coronary syndrome
Management of ACS should start as soon as it is suspected, but should not delay transfer to hospital. The recommendations in this section should be carried out in the order appropriate to the circumstances.
Offer pain relief as soon as possible. This may be achieved with GTN (sublingual or buccal), but offer intravenous opioids such as morphine, particularly if an acute myocardial infarction (MI) is suspected. 
Offer people a single loading dose of 300 mg aspirin as soon as possible unless there is clear evidence that they are allergic to it. If aspirin is given before arrival at hospital, send a written record that it has been given with the person.Only offer other antiplatelet agents in hospital. Follow the NICE guideline on acute coronary syndromes. 
Do not routinely administer oxygen, but monitor oxygen saturation using pulse oximetry as soon as possible, ideally before hospital admission. Only offer supplemental oxygen to:
people with oxygen saturation (SpO2) of less than 94% who are not at risk of hypercapnic respiratory failure, aiming for SpO2 of 94% to 98%
people with chronic obstructive pulmonary disease who are at risk of hypercapnic respiratory failure, to achieve a target SpO2 of 88% to 92% until blood gas analysis is available. Be aware that some pulse oximeters can underestimate or overestimate oxygen saturation levels, especially if the saturation level is borderline. Overestimation has been reported in people with dark skin. See also the NHS England Patient Safety Alert on the risk of harm from inappropriate placement of pulse oximeter probes.
Monitor people with acute chest pain, using clinical judgement to decide how often this should be done, until a firm diagnosis is made. This should include:
exacerbations of pain and/or other symptoms
pulse and blood pressure
heart rhythm
-xygen saturation by pulse oximetry
repeated resting 12lead ECGs and
checking pain relief is effective. 
Manage other therapeutic interventions using the NICE guideline on acute coronary syndromes. 

## Assessment in hospital for people with a suspected acute coronary syndrome
Take a resting 12lead ECG and a blood sample for high-sensitivity troponin I or T measurement (see the section on use of biochemical markers for diagnosis of an acute coronary syndrome) on arrival in hospital. 
Carry out a physical examination to determine:
haemodynamic status
signs of complications, for example, pulmonary oedema, cardiogenic shock and
signs of non-coronary causes of acute chest pain, such as aortic dissection. 
Take a detailed clinical history unless a STEMI is confirmed from the resting 12lead ECG (that is, regional STsegment elevation or presumed new LBBB). Record:
the characteristics of the pain
-ther associated symptoms
any history of cardiovascular disease
any cardiovascular risk factors and
details of previous investigations or treatments for similar symptoms of chest pain. 

## Use of biochemical markers for diagnosis of an acute coronary syndrome
Do not use high-sensitivity troponin tests for people in whom ACS is not suspected. 
For people at high or moderate risk of MI (as indicated by a validated tool), perform high-sensitivity troponin tests as recommended in the NICE diagnostics guidance on myocardial infarction. 
For people at low risk of MI (as indicated by a validated tool):
perform a second high-sensitivity troponin test as recommended in the NICE diagnostics guidance on myocardial infarction if the first troponin test at presentation is positive.
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). 
Ensure that patients understand that a detectable troponin on the first high-sensitivity test does not necessarily indicate that they have had an MI. 
Do not use biochemical markers such as natriuretic peptides and high-sensitivity C-reactive protein to diagnose an ACS. 
Do not use biochemical markers of myocardial ischaemia (such as ischaemia-modified albumin) as opposed to markers of necrosis when assessing people with acute chest pain. 
When interpreting high-sensitivity troponin measurements, take into account:
the clinical presentation
the time from onset of symptoms
the resting 12lead ECG findings
the pre-test probability of NSTEMI
the length of time since the suspected ACS
the probability of chronically elevated troponin levels in some people
that 99th percentile thresholds for troponin I and T may differ between sexes. 

## Making a diagnosis
When diagnosing MI, use the universal definition of myocardial infarction. This is the detection of rise and/or fall of cardiac biomarkers values  with at least one value above the 99th percentile of the upper reference limit and at least one of the following:
symptoms of ischaemia
new or presumed new significant STsegmentT wave (STT) changes or new LBBB
development of pathological Q waves in the ECG
imaging evidence of new loss of viable myocardium or new regional wall motion abnormality
identification of an intracoronary thrombus by angiography. 
When a raised troponin level is detected in people with a suspected ACS, reassess to exclude other causes for raised troponin (for example, myocarditis, aortic dissection or pulmonary embolism) before confirming the diagnosis of ACS. 
When a raised troponin level is detected in people with a suspected ACS, follow the NICE guideline on acute coronary syndromes until a firm diagnosis is made. Continue to monitor (see recommendation 1.2.3.4). 
When a diagnosis of ACS is confirmed, follow the NICE guideline on acute coronary syndromes. 
Reassess people with chest pain without raised troponin levels and no acute resting 12lead ECG changes to determine whether their chest pain is likely to be cardiac.If myocardial ischaemia is suspected, follow the recommendations on stable chest pain in this guideline (see the section on people presenting with stable chest pain). Use clinical judgement to decide on the timing of any further diagnostic investigations. 
Do not routinely offer non-invasive imaging or exercise ECG in the initial assessment of acute cardiac chest pain. 
Only consider early chest computed tomography (CT) to rule out other diagnoses such as pulmonary embolism or aortic dissection, not to diagnose ACS. 
Consider a chest Xray to help exclude complications of ACS such as pulmonary oedema, or other diagnoses such as pneumothorax or pneumonia. 
If an ACS has been excluded at any point in the care pathway, but people have risk factors for cardiovascular disease, follow the appropriate guidance, for example, the NICE guideline on cardiovascular disease and the NICE guideline on hypertension in adults. 

# People presenting with stable chest pain
This section of the guideline addresses the assessment and diagnosis of intermittent stable chest pain in people with suspected stable angina.
Exclude a diagnosis of stable angina if clinical assessment indicates non-anginal chest pain (see recommendation 1.3.3.1) and there are no other aspects of the history or risk factors raising clinical suspicion. 
If clinical assessment indicates typical or atypical angina (see recommendation 1.3.3.1), offer diagnostic testing (see the sections on diagnostic testing for people in whom stable angina cannot be excluded by clinical assessment alone, additional diagnostic investigations and use of non-invasive functional testing for myocardial ischaemia). 

## Clinical assessment
Take a detailed clinical history documenting:
the age and sex of the person
the characteristics of the pain, including its location, radiation, severity, duration and frequency, and factors that provoke and relieve the pain
any associated symptoms, such as breathlessness
any history of angina, MI, coronary revascularisation or other cardiovascular disease and
any cardiovascular risk factors. 
Carry out a physical examination to:
identify risk factors for cardiovascular disease
identify signs of other cardiovascular disease
identify non-coronary causes of angina (for example, severe aortic stenosis, cardiomyopathy) and
exclude other causes of chest pain. 

## Making a diagnosis based on clinical assessment
Assess the typicality of chest pain as follows:
Presence of three of the features below is defined as typical angina.
Presence of two of the three features below is defined as atypical angina.
Presence of one or none of the features below is defined as non-anginal chest pain.Anginal pain is:
constricting discomfort in the front of the chest, or in the neck, shoulders, jaw or arms
precipitated by physical exertion
relieved by rest or GTN within about 5 minutes. 
Do not define typical and atypical features of anginal chest pain and non-anginal chest pain differently in men and women. 
Do not define typical and atypical features of anginal chest pain and non-anginal chest pain differently in ethnic groups. 
Take the following factors, which make a diagnosis of stable angina more likely, into account when estimating people's likelihood of angina:
age
whether the person is male
cardiovascular risk factors including:
a history of smoking
diabetes
hypertension
dyslipidaemia
family history of premature coronary artery disease (CAD)
-ther cardiovascular disease
history of established CAD, for example, previous MI, coronary revascularisation. 
Unless clinical suspicion is raised based on other aspects of the history and risk factors, exclude a diagnosis of stable angina if the pain is non-anginal (see recommendation 1.3.3.1). Features which make a diagnosis of stable angina unlikely are when the chest pain is:
continuous or very prolonged and/or
unrelated to activity and/or
brought on by breathing in and/or
associated with symptoms such as dizziness, palpitations, tingling or difficulty swallowing.Consider causes of chest pain other than angina (such as gastrointestinal or musculoskeletal pain). 
Consider investigating other causes of angina, such as hypertrophic cardiomyopathy, in people with typical angina-like chest pain and a low likelihood of CAD. 
Arrange blood tests to identify conditions which exacerbate angina, such as anaemia, for all people being investigated for stable angina. 
Only consider chest Xray if other diagnoses, such as a lung tumour, are suspected. 
If a diagnosis of stable angina has been excluded at any point in the care pathway, but people have risk factors for cardiovascular disease, follow the appropriate guidance, for example, the NICE guideline on cardiovascular disease and the NICE guideline on hypertension in adults. 
For people in whom stable angina cannot be excluded on the basis of the clinical assessment alone, take a resting 12lead ECG as soon as possible after presentation. 
Do not rule out a diagnosis of stable angina on the basis of a normal resting 12lead ECG. 
Do not offer diagnostic testing to people with non-anginal chest pain on clinical assessment (see recommendation 1.3.3.1) unless there are resting ECG STT changes or Q waves. 
A number of changes on a resting 12lead ECG are consistent with CAD and may indicate ischaemia or previous infarction. These include:
pathological Q waves in particular
LBBB
STsegment and T wave abnormalities (for example, flattening or inversion).Note that the results may not be conclusive.Consider any resting 12lead ECG changes together with people's clinical history and risk factors. 
For people with confirmed CAD (for example, previous MI, revascularisation, previous angiography) in whom stable angina cannot be excluded based on clinical assessment alone, see recommendation 1.3.4.4 about functional testing. 
Consider aspirin only if the person's chest pain is likely to be stable angina, until a diagnosis is made. Do not offer additional aspirin if there is clear evidence that people are already taking aspirin regularly or are allergic to it. 
Follow the NICE guideline on stable angina while waiting for the results of investigations if symptoms are typical of stable angina. 

## Diagnostic testing for people in whom stable angina cannot be excluded by clinical assessment alone
The Guideline Development Group emphasised that the recommendations in this guideline are to make a diagnosis of chest pain, not to screen for CAD. Most people diagnosed with non-anginal chest pain after clinical assessment need no further diagnostic testing. However in a very small number of people, there are remaining concerns that the pain could be ischaemic.
Include the typicality of anginal pain features (see recommendation 1.3.3.1) in all requests for diagnostic investigations and in the person's notes. 
Use clinical judgement and take into account people's preferences and comorbidities when considering diagnostic testing. 
Offer 64slice (or above) CT coronary angiography if:
clinical assessment (see recommendation 1.3.3.1) indicates typical or atypical angina or
clinical assessment indicates non-anginal chest pain but 12lead resting ECG has been done and indicates STT changes or Q waves. 
For people with confirmed CAD (for example, previous MI, revascularisation, previous angiography), offer non-invasive functional testing when there is uncertainty about whether chest pain is caused by myocardial ischaemia. See the section on use of non-invasive functional testing for myocardial ischaemia for further guidance on non-invasive functional testing. An exercise ECG may be used instead of functional imaging. See also NICE's medical technologies guidance on HeartFlow FFRCT for estimating fractional flow reserve from coronary CT angiography. Using HeartFlow FFRCT may avoid the need for invasive coronary angiography and revascularisation for some patients

## Additional diagnostic investigations
Offer non-invasive functional imaging (see the section on use of non-invasive functional testing for myocardial ischaemia) for myocardial ischaemia if 64slice (or above) CT coronary angiography has shown CAD of uncertain functional significance or is non-diagnostic. 
Offer invasive coronary angiography as a third-line investigation when the results of non-invasive functional imaging are inconclusive. 

## Use of non-invasive functional testing for myocardial ischaemia
When offering non-invasive functional imaging for myocardial ischaemia use:
myocardial perfusion scintigraphy with single photon emission computed tomography (MPS with SPECT) or
stress echocardiography or
first-pass contrast-enhanced magnetic resonance (MR) perfusion or
MR imaging for stress-induced wall motion abnormalities.Take account of locally available technology and expertise, the person and their preferences, and any contraindications (for example, disabilities, frailty, limited ability to exercise) when deciding on the imaging method. . 
Use adenosine, dipyridamole or dobutamine as stress agents for MPS with SPECT and adenosine or dipyridamole for first-pass contrast-enhanced MR perfusion. 
Use exercise or dobutamine for stress echocardiography or MR imaging for stress-induced wall motion abnormalities. 
Do not use MR coronary angiography for diagnosing stable angina. 
Do not use exercise ECG to diagnose or exclude stable angina for people without known CAD. 

## Making a diagnosis following investigations
Significant coronary artery disease (CAD) found during CT coronary angiography is   70% diameter stenosis of at least one major epicardial artery segment or   50% diameter stenosis in the left main coronary artery:
Such factors allow less severe lesions (for example,   50%) to produce angina:
reduced oxygen delivery: anaemia, coronary spasm
increased oxygen demand: tachycardia, left ventricular hypertrophy
large mass of ischaemic myocardium: proximally located lesions
longer lesion length.
Well-developed collateral supply.
Small mass of ischaemic myocardium: distally located lesions, old infarction in the territory of coronary supply. 
Confirm a diagnosis of stable angina and follow the NICE guideline on stable angina when:
significant CAD (see box 1) is found during invasive or 64slice (or above) CT coronary angiography or
reversible myocardial ischaemia is found during non-invasive functional imaging. 
Investigate other causes of chest pain when:
significant CAD (see box 1) is not found during invasive coronary angiography or 64slice (or above) CT coronary angiography or
reversible myocardial ischaemia is not found during non-invasive functional imaging. 
Consider investigating other causes of angina, such as hypertrophic cardiomyopathy or syndrome X, in people with typical angina-like chest pain if investigation excludes flow-limiting disease in the epicardial coronary arteries. 

# Terms used in this guideline

## Chest pain
The term 'chest pain' is used throughout the guideline to mean chest pain or discomfort.# Recommendations for research
In 2010, the guideline committee made the following recommendations for research. The committee's full set of recommendations for research is detailed in the full guideline.

# Cost-effectiveness of multislice CT coronary angiography for ruling out obstructive coronary artery disease in people with troponin-negative acute coronary syndromes
Is multislice CT coronary angiography a cost-effective first-line test for ruling out obstructive coronary artery disease (CAD) in people with suspected troponin-negative acute coronary syndromes?

## Why this is important
Current European Society of Cardiology guidelines state that in troponin-negative ACS with no STsegment change on the ECG, 'a stress test is recommended... in patients with significant ischaemia during the stress test, coronary angiography and subsequent revascularisation should be considered'. Yet stress testing has relatively low sensitivity and specificity for diagnosing CAD in this group of people. Therefore a significant proportion of at-risk people are missed while others with normal coronary arteries are subjected to an unnecessary invasive coronary angiogram. Multislice CT coronary angiography is highly sensitive and provides a potentially useful means for early rule-out of CAD in troponin-negative acute coronary disease. We need to know whether it is cost effective compared with exercise ECG as a first test in the diagnostic work-up of this group.

# Refining the use of telephone advice in people with chest pain
In what circumstances should telephone advice be given to people calling with chest pain? Is the appropriateness influenced by age, sex or symptoms?

## Why this is important
The telephone is a common method of first contact with healthcare services, and produces a near uniform emergency response to chest pain symptoms. Such a response has considerable economic, social and human costs. Research should be conducted to clarify if an emergency response in all circumstances is appropriate, or if there are identifiable factors such as age, sex or associated symptoms that would allow a modified response and a more appropriate use of resources.

# Establishing a national registry for people who are undergoing initial assessment for stable angina
Can a national registry of people presenting with suspected angina be established to allow cohort analysis of treatments, investigations and outcomes in this group? Such a registry would provide a vital resource for a range of important research projects, including:
development and validation of a new score for assessing the pre-test probability of disease, addressing outstanding uncertainties in the estimation of the pre-test probability of CAD based on simple measures made at initial assessment (history, examination, routine bloods, resting 12lead ECG)
assessment of the extent to which new circulating biomarkers add additional information to measures made at initial assessment
provision of a framework for trial recruitment without significant work-up bias allowing evaluation of the diagnostic and prognostic test performance of CTbased, MR, echocardiography and radionuclide technologies.

## Why this is important
A national prospective registry of consecutive people with suspected stable angina before initial diagnostic testing does not currently exist in the UK or in any other country. Establishing such a registry would offer the following methodological strengths: statistical size, representative patients without work-up bias, contemporary data. This would overcome key problems in much of the existing evidence base.
Accurate assessment of pre-test likelihood of coronary disease is needed to inform the cost-effective choice of investigative technologies such as CT coronary calcium scoring for people with chest pain that may be caused by myocardial ischaemia. The data on which pre-test likelihood is based date from 1979 in a US population and may not be applicable to contemporary UK populations. There remain continuing uncertainties about the initial assessment of people with suspected stable angina. For example, the possible contributions of simple clinical measures such as body mass index, routine blood markers (for example, haemoglobin) or novel circulating biomarkers to estimates of the pre-test likelihood of CAD are not known and require further assessment in the whole population and in predefined subgroups including ethnic minorities.

# Information about presenting and explaining tests
All people presenting with chest pain will need to decide whether to accept the diagnostic and care pathways offered. How should information about the diagnostic pathway and the likely outcomes, risks and benefits, with and without treatment, be most effectively presented to particular groups of people, defined by age, ethnicity and sex?

## Why this is important
Methods of communication (both the content and delivery) will be guided by current evidence-based best practice. Controlled trials should be conducted based on well-constructed randomised controlled clinical trials comparing the effects of different methods of communication on the understanding of the person with chest pain. Such studies might consider a number of delivery mechanisms, including advice and discussion with a clinician or a specialist nurse, as well as specific information leaflets or visual data.
Any trials should also investigate the feasibility of introducing a suggested guideline protocol to be used with all people presenting with chest pain when faced with options concerning their clinical pathway.
Only by clearly explaining and then discussing the proposed diagnostic and care pathways can the healthcare professional be reasonably certain that informed consent has been obtained and that a patient's moral, ethical and spiritual beliefs, expectations, and any misconceptions about their condition, have been taken into account. Consideration should be given to any communication problems the person may have.# Putting this guideline into practice
NICE has produced tools and resources to help you put this guideline into practice.
Putting recommendations into practice can take time. How long may vary from guideline to guideline, and depends on how much change in practice or services is needed. Implementing change is most effective when aligned with local priorities.
Changes recommended for clinical practice that can be done quickly  like changes in prescribing practice  should be shared quickly. This is because healthcare professionals should use guidelines to guide their work  as is required by professional regulating bodies such as the General Medical and Nursing and Midwifery Councils.
Changes should be implemented as soon as possible, unless there is a good reason for not doing so (for example, if it would be better value for money if a package of recommendations were all implemented at once).
Different organisations may need different approaches to implementation, depending on their size and function. Sometimes individual practitioners may be able to respond to recommendations to improve their practice more quickly than large organisations.
Here are some pointers to help organisations put NICE guidelines into practice:
. Raise awareness through routine communication channels, such as email or newsletters, regular meetings, internal staff briefings and other communications with all relevant partner organisations. Identify things staff can include in their own practice straight away.
. Identify a lead with an interest in the topic to champion the guideline and motivate others to support its use and make service changes, and to find out any significant issues locally.
. Carry out a baseline assessment against the recommendations to find out whether there are gaps in current service provision.
. Think about what data you need to measure improvement and plan how you will collect it. You may want to work with other health and social care organisations and specialist groups to compare current practice with the recommendations. This may also help identify local issues that will slow or prevent implementation.
. Develop an action plan, with the steps needed to put the guideline into practice, and make sure it is ready as soon as possible. Big, complex changes may take longer to implement, but some may be quick and easy to do. An action plan will help in both cases.
. For very big changes include milestones and a business case, which will set out additional costs, savings and possible areas for disinvestment. A small project group could develop the action plan. The group might include the guideline champion, a senior organisational sponsor, staff involved in the associated services, finance and information professionals.
. Implement the action plan with oversight from the lead and the project group. Big projects may also need project management support.
. Review and monitor how well the guideline is being implemented through the project group. Share progress with those involved in making improvements, as well as relevant boards and local partners.
NICE provides a comprehensive programme of support and resources to maximise uptake and use of evidence and guidance. See our into practice pages for more information.
Also see Leng G, Moore V, Abraham S, editors (2014) Achieving high quality care  practical experience from NICE. Chichester: Wiley.# Context
Conditions causing chest pain or discomfort, such as an acute coronary syndrome or angina, have a potentially poor prognosis, emphasising the importance of prompt and accurate diagnosis. Treatments are available to improve symptoms and prolong life, hence the need for this guideline.
This guideline covers the assessment and diagnosis of recent onset chest pain or discomfort of suspected cardiac origin. In deciding whether chest pain may be cardiac and therefore whether this guideline is relevant, a number of factors should be taken into account. These include the person's history of chest pain, their cardiovascular risk factors, history of ischaemic heart disease and any previous treatment, and previous investigations for chest pain.
For pain that is suspected to be cardiac, there are two separate diagnostic pathways presented in the guideline. The first is for people with acute chest pain and a suspected acute coronary syndrome, and the second is for people with intermittent stable chest pain in whom stable angina is suspected. The guideline includes how to determine whether myocardial ischaemia is the cause of the chest pain and how to manage the chest pain while people are being assessed and investigated.
As far as possible, the recommendations in this guideline have been listed in the order in which they will be carried out and follow the diagnostic pathways. But, as there are many permutations at each decision point, it has been necessary to include frequent cross-referencing to avoid repeating recommendations several times.
The algorithms presented in full guideline show the two diagnostic pathways.
This guideline does not cover the diagnosis and management of chest pain that is unrelated to the heart (for example, traumatic chest wall injury, herpes zoster infection) when myocardial ischaemia has been excluded. The guideline also recognises that in people with a prior diagnosis of coronary artery disease, chest pain or discomfort is not necessarily cardiac.
The term 'chest pain' is used throughout the guideline to mean chest pain or discomfort.
The guideline will assume that prescribers will use a drug's summary of product characteristics to inform decisions made with individual patients.