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CORONARY HEART DISEASE
STRATEGIES FOR SECONDARY PREVENTION
Guidleines for management of the patient with angina
Definitions
* Stable angina Stable angina occurs when a patient experiences chest discomfort in a predictable pattern; episodes are predominantly exercise or stress related. The vast majority of patients with angina pectoris have obstructive coronary disease. However, in a minority of cases, angina pectoris may be secondary to other cardiac conditions, such as aortic stenosis or hypertrophic cardiomyopathy. Angina can also be exacerbated by non-cardiac conditions, including anaemia and thyrotoxicosis. A very small proportion of patients may have apparently normal coronary arteries.
* Unstable angina Unstable angina is a serious condition characterised by progressive symptoms which may include increased severity and increased frequency of pain, reduced effort capacity, rest pain and nocturnal pain. The pathology of unstable angina differs from that of stable angina; pathological features include plaque rupture, thrombus formation and vasospasm. The condition is associated with a high rate of infarction and demands urgent investigation and treatment.
Diagnosis of angina pectoris and initial investigations
Initial diagnosis of stable angina is based on a history of effort-related chest discomfort. With the exception of unstable angina, when the history is short, pain which is not effort related, or which lasts for several hours, is rarely angina. The presence of risk factors (cigarette smoking, hypertension, hypercholesterolaemia, a positive family history, diabetes mellitus) makes the diagnosis more likely. Examination is often unhelpful but may identify evidence of secondary causes (aortic stenosis, hypertrophic cardiomyopathy) and evidence of risk factors such as hypertension or hyperlipidaemia.
Initial investigation of angina
* ECG A normal ECG does not exclude significant coronary disease, but an abnormal ECG is helpful in identifying patients at particularly high risk.
* Blood tests These might include urea and electrolytes, full blood count, thyroid-function tests, random glucose and lipids (a non-fasting specimen is usually sufficient). Initial treatment
Aspirin All patients with angina should be treated with aspirin in a dose of 75-150 mg once daily. Treatment is usually for life.
Glyceryl trinitrate A glyceryl trinitrate spray or tablet should be given and patients should be advised to use these as required and also prophylactically.
Regular anti-anginal therapy Most patients require prophylactic anti-angina treatment with a beta-blocker, calcium-channel antagonist or long-acting nitrate. Any combination of these drugs may be used. Clinicians vary in which they prefer as a first-choice drug, although there is probably most evidence in favour of the beta-blocker in terms of reducing the frequency of angina and reducing GTN consumption.
Risk factor modification This involves advising patients to stop smoking, to diet (weight reducing and lipid lowering) and also the identification and treatment of hypertension. If coronary disease is later proven to be present, then aggressive lowering of cholesterol is indicated. Contrary to previous suggestions hormone replacement therapy is not contra-indicated in women with coronary disease and may even be beneficial.
Indications for referral to a cardiologist The following groups of patients should be considered for referral to a cardiologist.
1. All patients with unstable angina. These patients should be admitted directly or seen urgently at a clinic, depending on the severity of the symptoms.
2. Patients with angina that is limiting their lifestyle despite appropriate medical therapy. This might well include elderly patients who often benefit considerably from interventional treatment such as angioplasty or surgery.
3. Younger and middle-aged patients whose symptoms are controlled on medical therapy but in whom intervention may have some prognostic benefit. As an absolutely minimum level of investigation, these patients should be considered for exercise testing.
4. Patients who may have an underlying cause of their angina, such as aortic stenosis.
5. Patients with chest pain of uncertain cause. The purpose of investigation here is to clarify whether or not these patients have significant coronary artery disease. Investigation of angina in hospital The cornerstone of investigation of stable angina is the treadmill test. This is best performed in the context of a full cardiological referral to exclude diagnoses such as aortic stenosis and hypertrophic cardiomyopathy. In a limited number of patients, radionuclide investigation, using a treadmill, bicycle, or pharmaceutical stress, may be useful in diagnosing significant coronary disease.
Following non-invasive investigation, patients may then undergo coronary angiography to establish whether or not they have significant coronary disease or, if coronary disease has been proven, to determine their suitability for some form of coronary revascularisation, either by coronary angioplasty or by coronary bypass surgery. Patients with unstable angina will often proceed to
coronary angioplasty without prior exercise testing. |
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