The myocardial ischaemia. Further tests were perfusion scan or

The aim of rapid access chest pain clinics (RACPC) is to assess the
chest pain in order to identify coronary artery disease (CAD) with the use of
different diagnostic tests (National Service Framework for Coronary Artery
Disease, 2000). According to the report from the National Co-ordinating Centre
for NHS Service Delivery and Organisation (2005), there is a wide variation of
how the RACPC are configured, but the models of care are evolved to meet local
needs.  In 2010 NICE published the new
recommendation, which focuses on discharging low-risk patients, providing
medium-risk patients with imaging test and angiogram and initiating
anti-anginal treatment for the high-risk patients. Before 2010, patients arriving to RACPC underwent ETT as a
first diagnostic test to assess for myocardial ischaemia. Further tests were
perfusion scan or dobutamine stress ECHO in case if ETT was inconclusive. If
the tests were positive, patient was referred for a diagnostic coronary
angiogram, which could have progressed to angioplasty. If ETT would be
negative, a patient would be discharged from the RACPC.

Investigations
in RACPC may include such diagnostic tests as ETT, CT calcium scoring, CT
coronary angiogram, Stress ECHO and coronary angiogram. Usually, the first
cardiac test after patient’s history has been taken is resting ECG. It is a
cost-effective screening, which is considered as one of a number of diagnostic
tests that can help to predict the risk of CAD. It also can help in diagnosis
of atrial fibrillation and left ventricular hypertrophy. Unfortunately, resting
ECG does not exclude CAD and abnormal resting ECG increase the probability that
patient has CAD and there is no indication about the severity of CAD.

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ECG is a
non-invasive procedure which can help to detect the individuals at risk of
sudden cardiac death, acute MI, CAD and left ventricular dysfunction. ECG
allows to produce the accurate diagnosis of the heart rhythm and the heart rate
can be calculated by measuring the distance between two R waves. It measures
the electrical activity of the heart and used to assess arrhythmias, but does
not give any data on the mechanical function of the heart. ECG is a
non-invasive method, can be used for continuous monitoring, and is the only
device to assess arrhythmias. It also inexpensive and easy to perform and
equipment is widely available.

Although
the ECG is very useful in diagnosing CAD and many other cardiac conditions, it
produces only a static image and may not detect serious underlying heart
problems when the patients are not symptomatic. For example, when patient
arriving to RACPC with intermittent chest pain, it can be limiting in detection
of CAD as ECG could be normal at the time when the test is performed and ECG
during ETT may reflect underlying abnormality. In case if ECG is non-specific
and do not reflect any abnormality, can require additional evaluation and
tests, such as ECHO and ETT will be done. 

The majority
of patients with suspected angina will be referred for ETT. It is also known as
exercise ECG and stress ECG, and is usually performed on a treadmill. ETT is
considerable important in the evaluation known or suspected CAD and it also
provides significant prognostic information and frequently used for prediction
of future coronary events among the patients with CAD, previous MI or a history
of unstable angina (Manning, 2011). ETT can be accomplished with ECG and
imaging, such as echocardiography and nuclear perfusion imaging. One of the
disadvantages of the stress ECG is that it is not suitable for everybody, e.g.
patients with mobility or respiratory problems as it is used in patients who
are able to achieve an adequate heart rate. In this case, stress with imagining
could be performed by pharmacologic methods. Unfortunately, ETT cannot exclude
the presence of CAD, but highly abnormal result is a strong indication for the
further investigations. ETT is cost effective, no use of radiation involved and
gives the prognostic information.  It is
a standard test for assessing ischemia and functional capacity, however is not
as sensitive as stress imaging techniques, may give false positives and does not
localize ischemia.

For the
diagnosis and prognosis of CAD, non-invasive, more sensitive than ETT, stress
ECHO test, which provides information on the presence, can be used. It is
recommended for patients who are able to exercise but have baseline ECG abnormalities
(Manning, 2011). Among the advantages of this type of testing is short patient
time commitment, it is portable, there is no radiation involved and it also can
provide the information about the mass of the left ventricle and valvular
function. The most serious disadvantage of stress ECHO is that images are
subjectively interpreted and the accuracy depends on physician experience.
Patients should be able to attain an adequate level of exercise, it is defined
as >85% of the predicted maximal heart rate.

Dobutamine
stress ECHO is popular among the patients who are unable to complete exercise
stress test. Dobutamine rises heart rate and myocardial contractility.
Half-life is two minutes and the onset of action is within one to two minutes.
In case when the maximum predicted heart rate for patient’s age is not achieved
(85%) at the peak dose of dobutamine, atropine could be added. Although it
accurately assess CAD, there are some disadvantages of dobutamine ECHO: it
cannot assess functional capacity and can produce hyperemia and dangerous
ventricular arrhythmias in patients with poor left ventricular function or
severe coronary heart disease. Contraindication for dobutamine ECHO is
symptomatic aortic aneurism.

Myocardial
perfusion scintigraphy (MPS) is one among the non-invasive investigations,
which can reliably predict CAD. It can be used for patients with mobility
problems as part of the diagnostic testing for CAD. Comparing to stress ECHO,
myocardial perfusion imaging uses semi-automated computer quantification, which
increases accuracy and reproductivity. 
The development of myocardial perfusion imaging using ultrasound
contrast agents may allow improved assessment of wall motion and enhance the
diagnostic value of stress ECHO (Senior, 2005).

CT is a widely
available non-invasive method of assessment CAD by visualisation of coronary
circulation. There are several types of CT: Coronary CT angiography (CTA),
calcium-scoring screening scan and total body CT scan. The calcium-score scan
takes short amount of time and predicts future heart problems by detecting the
amount of calcium deposits in atherosclerotic plaque in coronary arteries. CTA
is also non-invasive imaging test, which is performed much faster than coronary
angiogram, it has lower risk and less discomfort to the patient. Since CT
scanners use X-rays, small amount of radiation can be exposed making it
unsuitable for pregnant patients or for those who is undergoing radiation
therapy.

Coronary
angiography is a procedure, which is used for assessing the severity of
disease, anatomy and nature of CAD. 
Unfortunately, it is an invasive investigation and can cause serious
complications and should only be considered after the non-invasive tests in
high-risk patients. There are many indications for invasive investigation of
the heart and it should be performed in patients if the estimated like hood of
CAD is 61–90% after suspicious findings on non-invasive investigations (NICE,
2000).

According to
RACPC Service Guideline, to establish or exclude CAD, patients’ history should
be taken and other risks, such as hypertension and family history are taken
into consideration. These procedure is followed by clinical examination with
the review of blood test results, done by GP before the patient is seen in
clinic. Blood pressure and resting 12 lead ECG is made before the estimation of
like hood that patient has CAD. For the estimation of the probability of CAD
the Pryor Risk Equation should be used, this equation includes following risk
factors: age, sex, family history of MI, smoking, type of the chest pain, ST/T
changes on ECG, diabetes mellitus and Q waves on ECG.

Usually, clinic process for
patient referred to RACPC, will be as following:

Family history and clinical examination, taking blood pressure
with review of blood test resultsResting ECGETT or other appropriate tests (e.g. stress ECHO)PrescribingAdvice should be given (e.g. smoking cessation, healthy eating
and weight reduction, use of GTN spray when appropriate)If appropriate, the referral for future investigations will be
arranged

The NICE guidance (2010)
suggests, that patients with pre-test probability (PTP) of 10-29% should
undergo computer tomography (CT) calcium scoring. Calcium score of zero taken
as confirmation that the risk of CAD is very low and patient is discharged. If
the calcium score is above zero, coronary angiogram is recommended. If PTP is
30-60%, functional imaging test, e.g. myocardial perfusion scintigraphy (MPS),
or stress cardiac magnetic resonance imaging is recommended. If PTP is high
(>90%), the patient is assumed to have CAD and no further investigations are
required to make the diagnosis. 

In 2010 Diamond-Forrester algorithm was accepted, which
measures the ‘pre-test probability’ (PTP) of CAD. It is based on gender, age
and symptoms present. The presence of all three features is defined as typical
angina, the presence two or one feature is defined as atypical angina. If the
probability of CAD is less than 10%, the patient is discharged, for the
probability of 10 – 29%, CT calcium scoring is recommended for the assessment
of CAD, which can include 64-slice CT angiogram, in case if calcium score is 1
to 400. For PTP 30 – 60%, patient is referred for the functional testing (such
as stress ECHO, stress CMR or MPS). If probability of CAD is more than 60%,
coronary angiogram is indicated.

All patients with suspected ischaemic heart
disease are offered an appointment within two weeks of a referral. There is no
evidence provided to explain this specific target of two weeks (The National
Service Framework for Coronary Artery Disease, 2013). Rapid access chest pain
clinics are run in variety of ways as it depends on local resources. For
example, the University College London Hospital accepts patients with new onset
chest pain, which is suspected to be cardiac, patients with known ischaemic
heart disease, are sent to the general cardiology unit. Unit offers following
diagnostic tests: ECG and consultation with cardiologist, and, if appropriate,
patient may need to have one or more of following diagnostic tests: chest
X-ray, ETT, for lower risk patients, RACPC offers CT coronary calcium scoring,
ECHO and stress ECHO, CT coronary angiogram, myocardial perfusion scan, 24 hour
ECG and coronary angiogram.

According to RACPC Service Guideline, there
is no age limit, however, University Hospitals of North Midlands RACPC unit
accepts only adult patients with clinical features of high or intermediate
probability of new onset angina. The service is not appropriate for patients
with diagnosed CAD, heart failure, cardiomyopathy and heart valve disease. It
is also not intended in case of suspected MI or unstable angina. RACPC in
University Hospitals of North Midlands adopted Diamond-Forrester chest pain
prediction rule. Clinic is run seven days per week by chest pain nurses,
doctors and on-call consultants. Patients undergo a clinical assessment and
have ETT, after which the further tests can be considered.

Patients, attending RACPC in Guy’s and St
Thomas hospital in London are offered resting ECG as a first diagnostic test,
and then they are due to see the nurse for chest pain assessment. It is after
the nurse discretion if patient needs ETT, X-ray or ECHO and all these tests
can be carried out on the same day following by rapid treatment if needed.

RACPC unit in Trafford Hospital and
Manchester Royal Infirmary offer examination by the nurse on arrival, following
by ETT or, if the patient is not able to undergo exercise tolerance test on a
treadmill, stress ECHO will be performed instead. Patient is asked to bring the
copy of prescription of the medication and to avoid strenuous exercise for 4
hours before stress test. Then, the patient will be seen by a nurse, who will
explain the results, and if necessary appropriate medication will be prescribed
or if the angina is suspected, an appointment with cardiac nurse will be
arranged. The same policy is run by RACPC at The James Cook University
Hospital.

Surrey Cardiac Network RACPC offers
investigation recommended by Surrey Cardiac Network Clinical Pathway, which has
been formulated in response to NICE Guidance 95. After diagnostic tests, such
as ETT or non-invasive imaging, all necessary treatment will be recommended.

NHS Lanarkshire states, that patients with
chest pains can be diagnosed and referred for the treatment at the same
appointment. This service is available at Hairmyres, Wishaw and Monklands
sites. At the clinic, all patients will undergo resting ECG, and, if specialist
nurse and cardiologist decide, patient will be referred for exercise ECG, ECHO
and X-ray in some cases. Cardiologist will discuss test results and any further
investigations or treatment will be arranged.

Specialised cardiac investigations are still
not available in many district general hospitals (DHS), which causes a delay in
establishing the diagnosis as patients need to wait for referral to a tertiary
centre (Liu et al., 2016).

There are
plenty of effective diagnostic tests used by different RACPC across the UK. The National Institute for Health and Care Excellence (NICE)
guidelines suggests that all patients should have an evaluation of
cardiovascular risk factors of CAD using Diamond and Forrester model and after
accepting this algorithm, majority of hospitals assess patients by pre-test
probability. After investigation, it comes to conclusion that the majority
hospitals across the UK successfully adopted NICE Guidance 95 and the main
tests offered at rapid access chest pain clinics are resting ECG, ETT or stress
ECHO. The National Institute for Health and Care
Excellence (NICE) guidelines suggest that all patients should have an
evaluation of cardiovascular risk factors of CAD using Diamond and Forrester
model.

 In case, when patients need further treatment,
they will be referred for additional diagnostic tests.