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Tuesday, 27 November 2012

The NICE Chest Pain Guidelines


The NICE Chest Pain Guidelines.

There is a lot of understandable confusion over the NICE chest pain guidelines.

It is true that when the 2010 guidelines were first launched, they created quite a stir, even amongst cardiologists, who struggled to agree on their interpretation.

Possibly, the biggest mistake NICE made, was to launch the "Management of New Onset Chest Pain Guidelines" almost 18 months before they updated the  "Management of Stable Angina" guidelines. These two guidelines are clearly designed to be interpreted in conjunction, and this delay led to considerable confusion.

The second mistake, was not to recognise the importance of 'prognostic' information in patients with angina, such as can be gained from an exercise ECG.


To clarify - there are two relevant Guidelines which need to be considered in conjunction.

1.  The Management of Chest Pain of Recent Onset - CG95 March 2010

2. The Management of Stable Angina CG126 - Updated July 2011

Diagnosing Angina

The first guideline (CG95) is all about diagnosis, in a patient presenting with new onset chest pain.

Pages 1-9 deal mainly with "unstable" chest pain (such as may occur at rest, without any triggers) and is suggestive of Acute Coronary Syndromes, and the management thereof.
Pages 10 onwards, deal with the management of newly presenting, but "stable", chest pain - i.e. the patient is well at the time of presentation and the symptoms are often predictable, short-lived and well-tolerated.  This is the section we will deal with here.

The guideline stresses that in many cases, a diagnosis of angina can be made clinically.
In these circumstances, exercise ECG's are not required to make the 'diagnosis'.  So, for example, those with classical symptoms, and a Coronary Artery Disease risk (CAD risk) likelihood of  >90% don't need further diagnostic tests. You can be pretty confident that they have angina.
But...The guidelines fail to point out, that an Exercise ECG can offer very important prognostic information, and help stratify that risk. For example, an exercise tolerance of >6 minutes of the Bruce protocol, before being limited by pain or ST changes, puts a patient with angina in a very good prognostic/low risk group.

According to NICE CG95 (The Management of Chest pain of recent onset) a diagnosis of angina can be excluded if the pain does not fulfil any of the following 3 criteria:

1. A constricting discomfort in the front of the chest, neck, shoulders, jaw or arms
2. Precipitaed by physical exertion
3. Relieved by rest - or GTN if tried - in under 5 minutes.

NICE goes on to define:
  • Typical Angina - as a pain which fulfils all three criteria (3/3)
  • Atypical Angina - as a pain that fulfils two of the three criteria (2/3)
  • Non-Angina - as a pain that fulfils one, or none, of the criteria. (0-1 /3)
The management of patients who only fulfil 0-1 of these criteria, no longer needs to follow the above guidelines. In other words, a pain which is "continuous or prolonged at rest, unrelated to activity, aggravated by breathing, or associated with other symptoms" is unlikely to be angina, and other causes should be considered.  

If 2 or more of these criteria are fulfilled, then we should go on to calculate a % CAD risk score (see below) to tell us the likelihood that this patient's symptoms are the result of significant underlying coronary disease.  Usually, this risk assessment is calculated at the RACPC, where patients can then be directed onwards to the most appropriate investigations. 

The RACPC

There are two common conditions worth mentioning, which often pop up at the RACPC as a cause  of chest pain.

Anaemia? 
When referring a patient to RACPC, it's always worth checking their FBC, renal function and lipid profile results before they get there.  Nothing more awkward than a patient arriving in clinic and looking up their FBC to find an Hb on 7g/dl and explaining that is the cause of their chest pain and no further cardiac tests are indicated.  

Aortic Stenosis?
Also - always check for murmurs in patients presenting with chest pain.  Aortic stenosis as a cause for angina should not be missed.  The management of this condition is completely different to that of coronary artery disease.  Any murmur should be clearly mentioned in the referral letter so that arrangements can be made for an ECHO on arrival, as part of the assessment. 


At the RACPC, the patient will be assessed with the following considerations in mind

1.  The history
2.  The risk factors
3.  Is the pain angina or not? (If not - what's the cause?) Can the diagnosis be made on clincial grounds, or are more tests needed?
4.  Is there any underlying IHD (if so - what's the prognosis? ) Consider further functional/anatomical tests.
4.  Who should be considered for revascularisation? (based on 3 + 4)

Don't be disheartened, as a GP, if your patient attends the RACPC and is discharged with a diagnosis of "non-cardiac chest pain".  It's not meant as an insult!
Firstly, don't forget, as GP's we have under 10 minutes to take a detailed history, examination, check risk factors, arrange tests, consider all the implications, share all that with the patient, and finally, read code every aspect of the consultation.
In the RACPC, the clinician has team of cardiac technicians, and sometimes up to 45 mins per patient, to establish a detailed history. Also, patient's stories do sometimes change! (Tell me about it - I have seen that with my own patients, whom I later felt embarrassed to have referred when assessed again by myself at RACPC!).

Secondly, The RACPC does have an another important role.  A number of clearly non-cardiac patients, need enhanced level reassurance to enable them to move forward, thus preventing the ongoing psychological morbidity associated with worry. Not to mention, repeated emergency admissions with non-cardiac chest pain.

At the RACPC  a % CAD score is calculated, but only those with chest pain which sounds suggestive of ischaemia.  Based on this score,  further tests of cardiac function are then offered to clarify any uncertainty in diagnosis.

Assessing Risk - What is the CAD risk score?

The CAD risk score estimates the percentage of people estimated to have Coronary Artery Disease according to age, sex, risk factors and typicality of symptoms.

Once the risk is assessed, the CAD score table (provided in the NICE guidelines) is used to assess the PRE-TEST likelihood of CAD.  A web-based alternative to using this numeric CAD scoring chart has been kindly provided by Dr Mark Dayer of The West Hertfordshire Hospitals:  Coronary Risk Assessment Dukes Score .
This on-line Tool is so quick and easy to use, most cardiologists find it far preferable to the numeric chart. 

  • If CAD risk <10% - Easy. Consider other causes of chest pain, or, if symptoms are classically angina, then consider other (non ischaemic) causes of angina  e.g. HOCM
  • If CAD risk >90% - Easy.  The guidelines state "Treat as stable angina without need for further diagnostic tests".  In other words, you've successfully made the diagnosis clinically, and continue to treat in accordance with the NICE Management of Stable Angina Guidelines (CG127).    True.  But they may still benefit from a prognostic test (see below).
  • If CAD risk is between 10-90% then other diagnostic tests many be indicated. This section is then divided into 3 further sub-groups. (see below)

For %CAD risk is between 10 and 90% The patients are subdivided into 3 groups:

          CAD risk 10-29%  - Offer CT calcium Scoring
          CAD risk 30-60%  - Offer non-invasive functional imaging (Stress ECHO/MIBI etc)
          CAD risk 61-90% -  Offer angiography, if acceptable, and if PCI is being considered.

This is not rocket science. Anyone can calculate the CAD risk score. True, if a GP has a confident grasp of the chest pain guidelines, and has open access to all the available cardiac imaging tests, then perhaps they could confidently manage all patients appropriately without the need to refer, until surgical intervention is required.  In reality, I don't think many GP's have open access for these tests, nor have the time or resources to take on this role from secondary care.

Arguably, those patients who would not chose to accept any surgical intervention, if offered, (PCI or CABG), and are well controlled on medical therapy, don't really need referral either. Like any health discussion, this is a decision which needs to be taken together, with their GP, after appropriate counselling and knowledge-sharing. It may be an entirely reasonable choice.
Would you want an angiogram/PCI even if all your symptoms are controlled on medication?
Some will. Some won't.


A word of note. The CAD % risk is a predictive score only. 
(It is based on a small research study of only 1030 patients between 1983 and 1985, at Dukes University Medical Centre, USA.  Of the 1030 patients, 168 underwent Angiography.)

What's more, the NICE risk score does not include other factors such as HDL, FH and ethnicity and in many ways this is disappointing. 


So Why Do An Exercise ECG?

NICE Say: "Do not use an exercise ECG to diagnose or exclude stable CAD"

But ... nothing stops us from choosing to use it once we've made a clinical diagnosis, yet want some prognostic information.


ETT are useful to
  • Assess or trigger symptoms (arrhythmias, valvular heart disease)
  • Assess exercise capacity
  • Provide prognostic information - e.g for DVLA
A sensible report from the RACPC might read something like this:

"Thank you for referring this 49yrs gentleman with a clinical diagnosis of atypical angina (i.e. Short-lived constricting left chest and arm pain, which has an inconsistent relationship to exertion). He managed 9 minutes of the Bruce protocol today before developing symptoms. There were no ST segment changes. If he does indeed have angina, today's test puts him in a good prognostic group. 
I note his various risk factors for IHD. 
His CAD risk score calculated  today is 45%.  In accordance with NICE guidelines, to help clarify the diagnosis, we will arrange another non-invasive test of cardiac function, such as a stress ECHO, and write with the results. 
In the meantime, he has been advised about lifestyle choices and the use of GTN/999 for prolonged symptoms".

Who needs Intervention?

Once angina has been diagnosed, the second guideline, Management of Stable Angina (CG126) comes into play.

According to NICE CG126, if a patient on optimal therapy (Note: This is defined as being on only one, or two, anti-anginal medications) and is still getting symptoms, then further intervention (PCI or CABG) should be considered.
So - even if you confidently diagnose Angina clinically in GP land, and start a beta-blocker of your choice -  unless symptoms are completely controlled, they may still need some further input via the RACPC.

In practice, when patients arrive at RACPC with classical ischaemic symptoms, they have often already been started, quite appropriately, on anti-anginal therapy by their GP. The RACPC therefore, is already in a position to consider if their symptoms are well controlled on treatment, or if further intervention may be required.

So, in summary, The Acute Trusts should not be selling all their Treadmills.  Not just yet anyway.

Simple?

Hope that helps, and that I haven't confused everyone even more.
H :-)


Acronym Guide:
NICE National Institute of clinical excellence
CG Clinical Guideline
ACS Acute Coronary Syndrome
CAD Coronary Artery Disease
RACPC Rapid Access Chest Pain Clinic


3 comments:

  1. This is a very helpful for my research. Thanks a lot.

    Galveston Heart Clinic

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    Replies
    1. Thanks Eline. Appreciate your feedback, and really glad you found it helpful. H.

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  2. Heather thanks for asking me to comment on the Blog

    This is a good precis of the guidance. NICE CG 95 is really about choosing the least worst test, i.e. minimising the number of tests to rule in/out angina. The drawback of perfusion or stress imaging is that it can tell you if ischaemia is present but not about the extent of underlying coronary artery disease. Anatomic tests such as CT or selective angiography provide additional information to guide preventative measures such as whether to prescribe a statin and indeed whether to prescribe a potent statin. Patients are also more motivated to improve their lifestyle if the know they have coronary disease, even if ti is subclinical.

    The implementation of the guidance is a challenge for cardiology departments across the country. Hospitals need access to more CT and stress imaging. The treadmill is not being completely abandoned. It still has it's place in providing assement of patient with know coronary disease and is useful reassurance for some low risk patients.

    Tom Hyde (Cardiologist)

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