Aidan MacDermott RN, MSc.
Research Nurse, Cardiology Department, Freeman Hospital, Newcastle upon Tyne Hospitals NHS Trust, Newcastle upon Tyne
Angina pectoris is a chronic medical condition caused by the obstruction of one or more of the coronary arteries by an atheromatous plaque or plaques. When the heart rate increases, the partially obstructed artery cannot supply the increase in oxygen demanded by the myocardium, resulting in myocardial ischaemia and anginal symptoms.
The patient with stable angina experiences shortness of breath and pain, pressure or heaviness in the chest beneath the breastbone (though it may also be felt in the left arm or shoulder, the neck or the lower jaw). The pain is brought on by physical exertion and is relieved by rest. If the patient does not receive effective treatment to prevent progressive narrowing and occlusion of the artery, the disease may progress to unstable angina, when the patient will be at very high risk of myocardial infarction (MI) and death.
Angina - a national problem
Although the death rate from coronary heart disease (CHD) has been falling in the UK since the late 1970s, it remains a serious national problem. Cardiovascular disease is the UK’s main cause of death, accounting for over 250,000 deaths each year (over 40 per cent of all deaths annually). About half of these deaths can be attributed to CHD, which is also the main cause of premature death: about one in four deaths in men, and one in five in women (British Heart Foundation, 2000).
Eighty per cent of patients with CHD are treated solely in primary care and in any one general practice, 4-5 per cent of patients will have CHD (Brown, 2000). Angina is the most common manifestation of CHD in the UK - about 1.5 million people are affected - and it is becoming more common (British Heart Foundation, 2000). At present, approximately one per cent of the population present to their general practitioner each year with new onset angina pain (Petticrew et al, 1998), and on average these patients consult their GP two to three times a year about their condition (de Bono, 1999). Despite its name, stable angina should be taken very seriously, since people with the condition have a threefold-increased risk of developing unstable angina, MI or sudden cardiac death within two years of presentation (de Bono, 1999).
National Service Framework
CHD was identified as a priority area for government action in the White Paper, Saving Lives: Our healthier nation (Department of Health, 1999). This is because CHD not only causes disability and an increased risk of death for the individual, but also has a high economic impact, costing the UK economy over £10 billion each year (British Heart Foundation, 2000). This bill consists of:
- National Health Service costs of about £1.6 billion a year (hospital care accounts for about 54 per cent of this sum, while buying and dispensing drugs contribute 32 per cent)
- Economic and social costs of about £8.5 billion each year due to days lost due to death, illness, and informal care.
In Saving Lives: Our healthier nation, the government set the `tough but attainable target’ of reducing death rates from CHD and stroke in people aged under 75 by at least 40 per cent by 2010 (Department of Health, 1999). A key method of achieving this aim is to improve the quality and consistency of health services in line with standards set out in national service frameworks (NSFs) for key disease areas. The National Service Framework for Coronary Heart Disease was the first NSF to be published (Department of Health, 2000). Stable angina is discussed in Standard 8, which sets out interventions and investigations, service models, immediate priorities, and targets for both primary and secondary care (Box 1) and reinforces previously published UK guidelines (de Bono, 1999).
Initial management of angina
The routine examinations and investigations that should be carried out when patients present to their GP with symptoms of angina are shown in Box 2.
History - The diagnosis is often apparent from the symptoms, especially if the history is typical, such as chest pain and/or breathlessness on exertion, during exercise, under emotional stress, after a large meal, in cold weather that is generally relieved by rest. Investigations are required to:
- Confirm the diagnosis in atypical presentations
- Assess the severity of the disease
- Exclude other conditions
- Distinguish the small number of patients whose angina is caused by hypertrophic cardiomyopathy or aortic stenosis.
Blood analysis - A full blood count should be requested, not only to exclude co-morbid conditions, but also because anaemia and hyperthyroidism can exacerbate angina. Serum cholesterol and plasma glucose levels should also be assessed, as these will have important implications for secondary prevention.
Blood pressure - The NSF follows the British Hypertension Society (BHS) guidelines in advocating target clinic blood pressures of [s6]140/85 mmHg for nondiabetic patients and 140/80mmHg for people with diabetes (Ramsay et al, 1999).
Electrocardiogram - A 12-lead resting electrocardiogram (ECG) is of low sensitivity in diagnosing CHD, since the reading will be normal in two-thirds of patients (North of England Stable Angina Guidelines Development Group, 1996). However, an abnormal reading may predict a poorer outcome - a higher risk of MI or sudden death - and indicates a need to refer the patient for further investigations.
Exercise tolerance test - An exercise tolerance test (ETT) on a treadmill should be performed on all patients with clinically certain angina, since it is effective in prognostically grouping patients. A strongly positive test at a low workload demands referral to a cardiologist because these patients are at higher risk of a cardiac event (Diercks et al, 2000). If a patient is unable to perform the test, they should be referred for a myocardial perfusion scan.
GPs and practice nurses will manage the majority of angina patients in the community, but some may need to be referred to hospital (Box 3). To avoid unnecessary referrals, the decision to seek specialist advice will be influenced by:
- Prognostic evaluation
- Duration of disease
- Patient preference
- Risk factors
- Clinical factors (diagnostic uncertainty)
- Threat to employment
- Unacceptable interference in lifestyle and recreation.
In patients with angina, a family history of CHD and diabetes are independent predictors of MI or death from CHD. Similarly, the extent of the disease is also predictive of outcome, in that patients with extensive, severe disease are at greater risk of a cardiac event. Surgical revascularisation with a coronary artery bypass graft (CABG) or percutaneous coronary intervention (PCI) may be indicated in these patients. PCI in stable angina does not increase chances of survival above medical therapy but does seem to give better relief of symptoms. In routine cases, mortality rates for PCI are about one per cent and for CABG are about three per cent (de Bono, 1999).
Older patients form a special subgroup that tends to have more extensive coronary artery disease. They are therefore at greater risk of a cardiac event and would benefit more from investigations and revascularisation. They may also have other co-morbid conditions that impair their mobility, so benefits from CABG/PCI may be greater in terms of symptom relief than in younger patients.
Management of angina
In patients with angina, the aims of management are to relieve symptoms with medical treatment, and to use drugs and lifestyle modification to reduce underlying risk factors for coronary atheroma and disease progression (de Bono, 1999). The NSF recommends that patients who are managed in primary care, should receive long-term follow-up, using structured consultations or cardiac prevention clinics (Department of Health, 2000). Patients with stable angina should be reviewed annually, although more frequent appointments will be needed in the initial period after diagnosis, or if blood pressure and cholesterol levels are being monitored.
Nurses can provide effective follow-up for patients with angina by carrying out regular checks (Box 4). Nurses are also well placed to reinforce adherence to medical treatment and lifestyle measures by offering support, encouragement and advice. Perhaps the most important advice that should be given to a patient with angina is when to call for help. If a patient experiences a prolonged episode of angina/chest pain (lasting 15 minutes or more), that does not respond to three doses of sublingual glyceryl trinitrate (GTN), they must call an ambulance immediately, in case they are having an MI.
Medical treatment for angina
Medical treatment can be divided into immediate symptom relief and background antianginal drugs. The efficacy of background antianginal drugs in reducing symptoms has been shown in placebo-controlled clinical trials but there is no direct evidence that any of these drugs lowers the incidence of sudden death or myocardial infarction. The choice of such drugs often depends on patient acceptability rather than superiority of one drug over another.
Symptom relief - Sublingual GTN remains the gold-standard treatment for the control of angina symptoms, and after the initial diagnosis, nurses should explain to patients why they need to ensure that a supply of the drug is always to hand.
Background antianginal medication - Several classes of agent are used as background antianginal medication, and the choice often depends on the drug’s acceptability to the individual patient. First-line medical treatment uses beta-blockers, but some patients cannot tolerate them due to their side-effects. These agents are also contraindicated for patients with asthma, and should be used with caution in those with heart failure, peripheral vascular disease (PVD) and diabetes.
First-line alternatives to beta-blockers - These drugs include a rate-lowering calcium antagonist (verapamil, diltiazem) or a potassium channel activator (nicorandil). A calcium antagonist should not be combined with a beta-blocker and should be used with caution in patients with heart failure. There are few contraindications to potassium channel activators. It is possible that their mode of action may offer particular advantages in angina, by mimicking the phenomenon known as ischaemic pre-conditioning. This natural protective response makes the heart’s myocardium more resistant to future infarct and seems to occur as a result of the opening of ATP-sensitive potassium channels (Yellon and Baxter, 2000). The role of nicorandil in angina is currently being assessed by the IONA study (Impact of Nicorandil on Angina), a large UK randomised, controlled trial involving 5000 patients. Results are due by the end of 2001.
Combination therapy - If monotherapy does not give symptomatic relief, then an additional antianginal - nicorandil, a nitrate (isosorbide mononitrate), or a calcium antagonist - may be added. If the patient still does not obtain symptomatic relief, it is unlikely that a third agent will be of any benefit (North of England Stable Angina Guidelines Development Group, 1996) and the patient should be considered for referral to a cardiologist for further management.
Medical treatment as secondary prevention
The combination of drugs used to reduce the risk of a cardiovascular event in patients with angina depends on the individual’s risk factors and co-morbidities, but even low-risk patients who have angina are likely to be taking a number of different medications (Box 5). This situation has obvious implications for patients’ adherence to treatment, and nurses should educate them about the rationale for the prescriptions and the need to comply with medication.
Antihypertensives - Both the NSF and the BHS guidelines recognise that their target blood pressures are challenging and that it may not be possible to achieve them in every patient (Department of Health, 2000; Ramsay et al, 1999). However, the NSF states that `practitioners should not be satisfied with pressures greater than 150mmHg systolic or 90mmHg diastolic in patients with angina. Consequently, many patients with angina are likely to be taking one or more antihypertensive drugs.
Antiplatelet therapy - All patients with angina should take 75mg aspirin unless it is contraindicated. Clopidogrel should be considered for patients who are unable to take aspirin or who experience a cardiovascular event while taking it.
Statin therapy - All patients with proven angina should have their fasting total serum cholesterol measured. Lipid-lowering drugs (statins) should only be used within an overall lifestyle management strategy, and any patient with a cholesterol level >5mmol/1 should be treated with the aim of reducing total serum cholesterol to <5mmo1/1 or achieving a reduction of 30 per cent, whichever is greater.
ACE inhibitors - There is some evidence that angiotensin converting enzyme (ACE) inhibitors may have a place in angina management, but their exact role is still under examination in ongoing clinical studies.
People with diabetes - People in this patient group are at very high risk of a cardiac event. Post-prandial glucose peaks are independently related to cardiovascular mortality (DECODE study group, 1999). Patients with diabetes should, therefore receive very careful follow-up to promote compliance with their hypoglycaemic treatment.
Smoking, obesity, a high-fat, high-salt diet and lack of regular exercise are all recognised risk factors for CHD, and nurses can help individuals change lifestyle and reduce risk. However, health promotion is only effective if the nurses involved consult both the patient and his or her family.
Patients’ views on the causes of and risk factors for CHD are crucial in their adherence to medical treatment and acceptance of lifestyle modification. If patients have a negative view of the causes of CHD, then this is likely to have a negative effect on quality of life and may even have an adverse effect on outcomes (Furze and Lewin, 2000).
Nurses should realise that as health professionals, their views are likely to differ from patients’ understanding of angina and the risk factors for CHD. Men are more likely to cite controllable factors such as diet and lack of exercise as the most significant causes of angina, whereas women are more likely to believe that uncontrollable factors, such as family history and stress, are most significant (Furze and Lewin, 2000).
A number of studies have revealed a relationship between the frequency and severity of angina symptoms, and anxiety and depression. This anxiety and depression is independent of the extent of coronary artery disease (Lewin, 1999). It is possible that the physiological effects of anxiety, increased autonomic response and vasoconstriction, may induce angina. In these patients it is unlikely that medical therapy alone will control symptoms, and many are likely to require referral to a cardiologist.
Staff at York University have developed a cognitive behaviour disease management programme. In a small pilot study, the programme produced a 70 per cent reduction in episodes of angina and a 72 per cent improvement in quality of life (Lewin et al, 1995). The programme is currently the subject of a larger trial and results should be published soon (Lewin and Furze, 2001).
The National Service Framework for Coronary Heart Disease has reinforced previous UK guidelines. It has set out appropriate investigations and treatment aimed at reducing symptoms and improving the prognosis for patients with stable angina (Department of Health, 2000; de Bono, 1999). Nurses will play a pivotal role in achieving NSF targets, as they are able to take into account patients’ perspectives and needs. These are crucial factors in the success of any treatment strategy.
Box 1. National service framework (NSF) for cardiovascular disease
The NSF recommends that patients with angina should receive:
- Appropriate investigations
- Estimation of their risk of disease progression and cardiovascular events
- Treatment to relieve symptoms
- Treatment to reduce cardiovascular risk
- Assessment of the benefits of revascularisation
NSF ‘milestones’ include:
- By April 2001, there should be 50 rapid-access chest pain clinics to help ensure that people with new symptoms indicating angina will be seen by a specialist within two weeks of referral. There should be 100 such clinics by April 2002
- By April 2001, every general practice should have a systematically developed and maintained CHD register that is used to plan care, together with appropriate medical records, for people on long-term drug therapy
- By April 2002, every practice should have a locally agreed protocol describing the systematic assessment, treatment, and follow-up of patients with angina
Source: Department of Health (2000).
Box 2. Routine tests and examination
The following tests are recommended for patients presenting with symptoms of angina:
- Clinical examination
- Full blood count
- Thyroid function test
- Cholesterol level
- Glucose level
- Blood pressure
- Exercise tolerance test
Source. Department of Health (2000).
Box 3. Criteria for referral in angina
Patients should be referred if:
- They have a positive exercise tolerance test at a low workload
- The GP is uncertain of the diagnosis
- The GP requires advice on management
- The patient’s symptoms are refractory to medical therapy
- The patient would benefit from prognostic investigations and specialist treatment
Source: North of England Stable Angina Guidelines Development Group (1996).
Box 4. Components of a GP angina clinic
- Blood pressure check*
- Cholesterol level*
- Haemoglobin level*
- Thyroid function test*
- ECG recording for new abnormalities
- Advice on use of sublingual GTN for chest pain
- Symptom evaluation
- Review of medication
- Advice on lifestyle modification
* If previously abnormal
Source: North of England Stable Angina Guidelines Development Group (1996).
Box 5. Secondary prevention
- Anti hypertensive therapy
- Antiplatelet therapy
- Lipid-lowering drugs
- Aggressive treatment of diabetes
- ACE inhibitors
- Smoking cessation
- Weight loss where appropriate
- Healthy diet
- Regular exercise
Source: North of England Stable Angina Guidelines Development Group (1996).
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