The aim of rapid access chest pain clinics (RACPC) is to assess thechest pain in order to identify coronary artery disease (CAD) with the use ofdifferent diagnostic tests (National Service Framework for Coronary ArteryDisease, 2000). According to the report from the National Co-ordinating Centrefor NHS Service Delivery and Organisation (2005), there is a wide variation ofhow the RACPC are configured, but the models of care are evolved to meet localneeds. In 2010 NICE published the newrecommendation, which focuses on discharging low-risk patients, providingmedium-risk patients with imaging test and angiogram and initiatinganti-anginal treatment for the high-risk patients. Before 2010, patients arriving to RACPC underwent ETT as afirst diagnostic test to assess for myocardial ischaemia.
Further tests wereperfusion scan or dobutamine stress ECHO in case if ETT was inconclusive. Ifthe tests were positive, patient was referred for a diagnostic coronaryangiogram, which could have progressed to angioplasty. If ETT would benegative, a patient would be discharged from the RACPC.Investigationsin RACPC may include such diagnostic tests as ETT, CT calcium scoring, CTcoronary angiogram, Stress ECHO and coronary angiogram. Usually, the firstcardiac test after patient’s history has been taken is resting ECG. It is acost-effective screening, which is considered as one of a number of diagnostictests that can help to predict the risk of CAD. It also can help in diagnosisof atrial fibrillation and left ventricular hypertrophy.
Unfortunately, restingECG does not exclude CAD and abnormal resting ECG increase the probability thatpatient has CAD and there is no indication about the severity of CAD. ECG is anon-invasive procedure which can help to detect the individuals at risk ofsudden cardiac death, acute MI, CAD and left ventricular dysfunction. ECGallows to produce the accurate diagnosis of the heart rhythm and the heart ratecan be calculated by measuring the distance between two R waves. It measuresthe electrical activity of the heart and used to assess arrhythmias, but doesnot give any data on the mechanical function of the heart. ECG is anon-invasive method, can be used for continuous monitoring, and is the onlydevice to assess arrhythmias. It also inexpensive and easy to perform andequipment is widely available.Althoughthe ECG is very useful in diagnosing CAD and many other cardiac conditions, itproduces only a static image and may not detect serious underlying heartproblems when the patients are not symptomatic.
For example, when patientarriving to RACPC with intermittent chest pain, it can be limiting in detectionof CAD as ECG could be normal at the time when the test is performed and ECGduring ETT may reflect underlying abnormality. In case if ECG is non-specificand do not reflect any abnormality, can require additional evaluation andtests, such as ECHO and ETT will be done. The majorityof patients with suspected angina will be referred for ETT. It is also known asexercise ECG and stress ECG, and is usually performed on a treadmill. ETT isconsiderable important in the evaluation known or suspected CAD and it alsoprovides significant prognostic information and frequently used for predictionof future coronary events among the patients with CAD, previous MI or a historyof unstable angina (Manning, 2011).
ETT can be accomplished with ECG andimaging, such as echocardiography and nuclear perfusion imaging. One of thedisadvantages 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 whoare able to achieve an adequate heart rate. In this case, stress with imaginingcould be performed by pharmacologic methods. Unfortunately, ETT cannot excludethe presence of CAD, but highly abnormal result is a strong indication for thefurther investigations. ETT is cost effective, no use of radiation involved andgives the prognostic information. It isa standard test for assessing ischemia and functional capacity, however is notas sensitive as stress imaging techniques, may give false positives and does notlocalize ischemia.
For thediagnosis and prognosis of CAD, non-invasive, more sensitive than ETT, stressECHO test, which provides information on the presence, can be used. It isrecommended for patients who are able to exercise but have baseline ECG abnormalities(Manning, 2011). Among the advantages of this type of testing is short patienttime commitment, it is portable, there is no radiation involved and it also canprovide the information about the mass of the left ventricle and valvularfunction. The most serious disadvantage of stress ECHO is that images aresubjectively interpreted and the accuracy depends on physician experience.
Patients should be able to attain an adequate level of exercise, it is definedas >85% of the predicted maximal heart rate. Dobutaminestress ECHO is popular among the patients who are unable to complete exercisestress 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 itaccurately assess CAD, there are some disadvantages of dobutamine ECHO: itcannot assess functional capacity and can produce hyperemia and dangerousventricular arrhythmias in patients with poor left ventricular function orsevere coronary heart disease. Contraindication for dobutamine ECHO issymptomatic aortic aneurism.Myocardialperfusion scintigraphy (MPS) is one among the non-invasive investigations,which can reliably predict CAD.
It can be used for patients with mobilityproblems as part of the diagnostic testing for CAD. Comparing to stress ECHO,myocardial perfusion imaging uses semi-automated computer quantification, whichincreases accuracy and reproductivity. The development of myocardial perfusion imaging using ultrasoundcontrast agents may allow improved assessment of wall motion and enhance thediagnostic value of stress ECHO (Senior, 2005).CT is a widelyavailable non-invasive method of assessment CAD by visualisation of coronarycirculation. There are several types of CT: Coronary CT angiography (CTA),calcium-scoring screening scan and total body CT scan.
The calcium-score scantakes short amount of time and predicts future heart problems by detecting theamount of calcium deposits in atherosclerotic plaque in coronary arteries. CTAis also non-invasive imaging test, which is performed much faster than coronaryangiogram, it has lower risk and less discomfort to the patient. Since CTscanners use X-rays, small amount of radiation can be exposed making itunsuitable for pregnant patients or for those who is undergoing radiationtherapy.Coronaryangiography is a procedure, which is used for assessing the severity ofdisease, anatomy and nature of CAD. Unfortunately, it is an invasive investigation and can cause seriouscomplications and should only be considered after the non-invasive tests inhigh-risk patients. There are many indications for invasive investigation ofthe heart and it should be performed in patients if the estimated like hood ofCAD is 61–90% after suspicious findings on non-invasive investigations (NICE,2000).According toRACPC Service Guideline, to establish or exclude CAD, patients’ history shouldbe taken and other risks, such as hypertension and family history are takeninto consideration.
These procedure is followed by clinical examination withthe review of blood test results, done by GP before the patient is seen inclinic. Blood pressure and resting 12 lead ECG is made before the estimation oflike hood that patient has CAD. For the estimation of the probability of CADthe Pryor Risk Equation should be used, this equation includes following riskfactors: age, sex, family history of MI, smoking, type of the chest pain, ST/Tchanges on ECG, diabetes mellitus and Q waves on ECG.Usually, clinic process forpatient referred to RACPC, will be as following: Family history and clinical examination, taking blood pressurewith review of blood test resultsResting ECGETT or other appropriate tests (e.g. stress ECHO)PrescribingAdvice should be given (e.g. smoking cessation, healthy eatingand weight reduction, use of GTN spray when appropriate)If appropriate, the referral for future investigations will bearrangedThe NICE guidance (2010)suggests, that patients with pre-test probability (PTP) of 10-29% shouldundergo computer tomography (CT) calcium scoring.
Calcium score of zero takenas confirmation that the risk of CAD is very low and patient is discharged. Ifthe calcium score is above zero, coronary angiogram is recommended. If PTP is30-60%, 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 arerequired to make the diagnosis. In 2010 Diamond-Forrester algorithm was accepted, whichmeasures the ‘pre-test probability’ (PTP) of CAD. It is based on gender, ageand symptoms present. The presence of all three features is defined as typicalangina, the presence two or one feature is defined as atypical angina.
If theprobability of CAD is less than 10%, the patient is discharged, for theprobability of 10 – 29%, CT calcium scoring is recommended for the assessmentof CAD, which can include 64-slice CT angiogram, in case if calcium score is 1to 400. For PTP 30 – 60%, patient is referred for the functional testing (suchas stress ECHO, stress CMR or MPS). If probability of CAD is more than 60%,coronary angiogram is indicated.
All patients with suspected ischaemic heartdisease are offered an appointment within two weeks of a referral. There is noevidence provided to explain this specific target of two weeks (The NationalService Framework for Coronary Artery Disease, 2013). Rapid access chest painclinics are run in variety of ways as it depends on local resources. Forexample, the University College London Hospital accepts patients with new onsetchest pain, which is suspected to be cardiac, patients with known ischaemicheart disease, are sent to the general cardiology unit. Unit offers followingdiagnostic tests: ECG and consultation with cardiologist, and, if appropriate,patient may need to have one or more of following diagnostic tests: chestX-ray, ETT, for lower risk patients, RACPC offers CT coronary calcium scoring,ECHO and stress ECHO, CT coronary angiogram, myocardial perfusion scan, 24 hourECG and coronary angiogram.According to RACPC Service Guideline, thereis no age limit, however, University Hospitals of North Midlands RACPC unitaccepts only adult patients with clinical features of high or intermediateprobability of new onset angina. The service is not appropriate for patientswith diagnosed CAD, heart failure, cardiomyopathy and heart valve disease. Itis also not intended in case of suspected MI or unstable angina.
RACPC inUniversity Hospitals of North Midlands adopted Diamond-Forrester chest painprediction rule. Clinic is run seven days per week by chest pain nurses,doctors and on-call consultants. Patients undergo a clinical assessment andhave ETT, after which the further tests can be considered.
Patients, attending RACPC in Guy’s and StThomas 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 afterthe nurse discretion if patient needs ETT, X-ray or ECHO and all these testscan be carried out on the same day following by rapid treatment if needed. RACPC unit in Trafford Hospital andManchester Royal Infirmary offer examination by the nurse on arrival, followingby ETT or, if the patient is not able to undergo exercise tolerance test on atreadmill, stress ECHO will be performed instead. Patient is asked to bring thecopy of prescription of the medication and to avoid strenuous exercise for 4hours before stress test. Then, the patient will be seen by a nurse, who willexplain the results, and if necessary appropriate medication will be prescribedor if the angina is suspected, an appointment with cardiac nurse will bearranged. The same policy is run by RACPC at The James Cook UniversityHospital.Surrey Cardiac Network RACPC offersinvestigation recommended by Surrey Cardiac Network Clinical Pathway, which hasbeen formulated in response to NICE Guidance 95. After diagnostic tests, suchas ETT or non-invasive imaging, all necessary treatment will be recommended.
NHS Lanarkshire states, that patients withchest pains can be diagnosed and referred for the treatment at the sameappointment. This service is available at Hairmyres, Wishaw and Monklandssites. At the clinic, all patients will undergo resting ECG, and, if specialistnurse and cardiologist decide, patient will be referred for exercise ECG, ECHOand X-ray in some cases. Cardiologist will discuss test results and any furtherinvestigations or treatment will be arranged.Specialised cardiac investigations are stillnot available in many district general hospitals (DHS), which causes a delay inestablishing the diagnosis as patients need to wait for referral to a tertiarycentre (Liu et al., 2016).There areplenty 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 ofcardiovascular risk factors of CAD using Diamond and Forrester model and afteraccepting this algorithm, majority of hospitals assess patients by pre-testprobability.
After investigation, it comes to conclusion that the majorityhospitals across the UK successfully adopted NICE Guidance 95 and the maintests offered at rapid access chest pain clinics are resting ECG, ETT or stressECHO. The National Institute for Health and CareExcellence (NICE) guidelines suggest that all patients should have anevaluation of cardiovascular risk factors of CAD using Diamond and Forrestermodel. In case, when patients need further treatment,they will be referred for additional diagnostic tests.