Angina Pectoris

Angina is chest pain or discomfort that is caused when heart muscle does not get enough blood. Angina results from the demands of the myocardium being unable to be met by blood supply. This usually implies narrowing of one of more coronary arteries and it tends to occur at times when the heart has to do more work, e.g. with exercise.

Angina can much less often be caused by valve disease, especially aortic stenosis, hypertrophic obstructive cardiomyopathy, hypertensive heart disease, arrhythmias, arteritis and anaemia.

• Stable angina is when the pain is precipitated by predictable factors, usually exercise.
• Unstable angina is when it occurs at any time, possibly at rest. Unstable angina, unlike myocardial infarction pain, is relieved by GTN.

• It is estimated that just under 2 million people in the UK have, or have had, angina. The prevalence of angina is higher in men than in women, and increases sharply with age.¹
• The prevalence of angina in women increases from 0.1-1% in those aged 45-54 years to 10-15% in those aged 65-74 years.²
• The prevalence of angina in men increases from 2-5% in those aged 45-54 years to 10-20% in those aged 65-74 years.²
• People of South Asian origin in the UK have an increased risk of ischaemic heart disease but black Caribbean people have a reduced risk compared with the overall UK population rate.
• In both men and women the rate is significantly higher in lower socio-economic groups.

Risk factors

• Risk factors for cardiovascular disease include family history, cigarette smoking, diabetes mellitus, metabolic syndrome, hyperlipidaemia, hypertension, obesity and lack of exercise.

• Diagnosis is based on the history: there are no characteristic features on examination and special investigations are used to confirm the cause of the angina. Clinical suspicion is required and it is important not to accept the patient's own diagnosis.
• The typical pain of angina is often described as a tight, dull or heavy feeling of discomfort.
• The patient may clench their fist to indicate a crushing pain or spread his fingers and push on his chest to indicate a diffuse pressing pain.
• Using one finger to indicate a point it is most unlikely to be cardiac in origin.
• A burning pain is more likely to be due to gastro-oesophageal reflux although this differentiation is not entirely reliable.
• Distribution of the pain: may be retrosternal, over the whole praecordium or largely on the left side of the chest. It is uncommon in the back, but may radiate into the neck, jaw, epigastrium or left arm.
• Precipitating factors:
  • Relationship to exertion: the symptoms typically last up to several minutes after exertion or emotional stress has stopped.
  • Cold weather is an aggravating factor: a classical precipitant is having to walk up an incline into a cold wind.
  • Pain may be brought on by emotion or after a heavy meal when cardiac output may rise by 20%.
  • In stable angina symptoms should be reproducible and anticipation of pain in response to a certain level of exertion should be possible.
• Note risk factors for coronary heart disease (CHD); if two or more are present the diagnosis is much more likely.
• If the patient has GTN, this should help to alleviate the pain but doing so is not diagnostic. Gastro-oesophageal reflux is also often relieved by GTN.

Examination

• Full general examination: include body mass index and blood pressure. Features of hypercholesterolaemia, e.g. xanthelasma or tendon xanthoma may be noted.
• Check blood pressure.
• Examination of the pulse includes rate and regularity. Atrial fibrillation reduces cardiac output and suggests CHD. Bradycardia also reduces cardiac output. Tachycardia may suggest anaemia.
• Listen for a murmur (see auscultation of the heart). Is there aortic stenosis or aortic sclerosis - the latter indicates atherosclerosis. There may be a flow murmur in anaemia or thyrotoxicosis.
• Perform urinalysis: check for glucose in case of a recent onset of diabetes.
• Check for clinical indications of other cardiovascular disease, e.g. peripheral vascular disease.

• Acute myocardial infarction: pain lasts longer than 5 minutes and is not relieved by rest.
• Prinzmetal angina occurs at rest and exhibits a circadian pattern, with most episodes occurring in the early hours of the morning.
• Acute pericarditis: tends to be a more constant pain, which is aggravated by inspiration, lying flat, swallowing and movement
• Musculoskeletal pain: worse on movement but it is the movements rather than general exercise that cause the pain. There may be injury to the chest wall or pain from the thoracic spine. Deep inspiration and rotation are likely to aggravate the pain and there may be local tenderness.
• Gastro-oesophageal reflux: often a burning pain, most common on lying down and after meals. Exercise may aggravate the pain, which is relieved by acid/ alginate mixtures and much reduced by a course of a proton pump inhibitor.
• Pleuritic chest pain: the pain is sharp on deep inspiration. It may occur with infection, especially pneumonia, or with infarction following a pulmonary embolism. There may well be purulent sputum or haemoptysis.
• Aortic dissection: causes a more constant pain.
• Gall stones can cause acute cholecystitis but the pain is not related to exercise.

• A full 12 lead ECG will probably show some ischaemic changes but there may be none at rest. If there are ECG changes this implies a poor prognosis and suggests urgent referral.
• Full blood count is required to exclude anaemia.
• Renal function and electrolytes to assess renal function.
• Fasting blood glucose if diabetes is not known to exist. If diabetes is known and recent figures are not available then glycosylated haemoglobin and microalbuminuria should be checked.
• Fasting blood cholesterol and triglycerides, including the ratio of total cholesterol to high density cholesterol (TC/ HDL-C).
• Baseline liver function tests before starting statins.
• Check thyroid function tests: thyrotoxicosis will increase the work of the heart whilst hypothyroidism is associated with raised cholesterol.
• Cardiac enzymes will be needed if there is a suggestion of permanent myocardial damage (from history or recent ECG changes). These cases need emergency admission in most circumstances.
• The first specific investigation for stable angina is exercise ECG testing. Those patients who are unable to undergo exercise tolerance testing or who have pre-existing ECG abnormalities should be considered for myocardial perfusion scintigraphy.³
• Myocardial perfusion scintigraphy (MPS) using single photon emission computed tomography (SPECT) is recommended by NICE for the diagnosis of suspected coronary artery disease in the following circumstances:⁴
  • As the initial diagnostic tool for people with suspected CAD for whom stress ECG testing poses particular problems of poor sensitivity or difficulties in interpretation, including women, patients with cardiac conduction defects (e.g. left bundle branch block), and people with diabetes, and also for people for whom treadmill exercise is difficult or impossible.
  • As part of the investigation strategy in the management of established CAD in people who remain symptomatic following myocardial infarction or reperfusion interventions.
• Further and more specific investigations include coronary angiography and possibly echocardiography if cardiac function is in doubt or aortic valve disease is suspected.
• Coronary angiography should be considered when patients are considered to be high risk or when the diagnosis remains unclear.³

It is important not to delay treatment while awaiting referral. Reasons for referral include:⁵

• Previous myocardial infarction, coronary artery bypass grafting, or percutaneous transluminal coronary angioplasty
• Electrocardiograph evidence of a previous MI, or other significant abnormality
• Fail to respond to medical treatment
• Ejection systolic murmur suggesting aortic stenosis
• Further reasons for referral
• Confirm or refute the diagnosis if uncertain or atypical symptoms
• Advise on management, especially if the person has not responded to treatment or risk-factor modification
• Presence of several risk factors or a strong family history
• Person's preference for referral
• Problems with employment, life insurance, or unacceptable interference with lifestyle
• Significant comorbidity (e.g. diabetes)

• The patient should be referred for an exercise ECG without delay. Patients with severe coronary artery disease are at high risk of myocardial infarction and this may be fatal. Refer to rapid-access chest pain clinic, open-access exercise testing or cardiology outpatient services depending on local protocol and availability.
• Includes modification of lifestyle, pharmacological interventions to reduce risk and specific treatment of the angina. Treatment of angina should not wait for exercise testing or referral to a cardiologist, even if the drugs have to be stopped for the test.
• Carefully consider the diagnosis. If there was prolonged pain within the last 24 hours and it was not swiftly relieved by rest it must be asked if the patient has had a myocardial infarction. An immediate ECG may help but false negatives may mislead. If there is doubt, admission to hospital can be justified. Troponins or cardiac enzymes may be of value but in the meantime it may be safest if the patient is in hospital if a very recent MI is possible.
• The patient must be informed of the diagnosis and its implications. He must be informed that if the pain lasts longer than 5 minutes, especially if it is unresponsive to GTN, this may be a heart attack and he should dial 999 for an ambulance without delay.
• Arrange early review for efficacy of drugs in order to achieve optimum medication and dose and to ensure patient has a full understanding of angina, implications and importance of treatment, and the need to reduce any specific cardiovascular risk factors.

Drug treatment

• The patient should be given GTN in tablet or spray form, along with instructions for how to use it and expected side effects. It may be used when the pain appears and should help alleviate it faster. If pain is anticipated, as when approaching a hill, the medication can be taken to prevent the pain.
• Long acting nitrate tablets may be used in addition. They do not last 24 hours as it is important to have a break during the day to prevent tolerance. They are usually taken in the morning to cover the activity of the day with a break at night.
• Beta blockers are usually very effective in the control of angina but there may be contraindications such as chronic obstructive pulmonary disease.
• If beta blockers are contraindicated or if they fail to give adequate control of symptoms, an alternative drug may be used or added. The choice includes an appropriate calcium channel blocker, isosorbide mononitrate or a potassium channel activator such as nicorandil or nicardipine.
• For monotherapy, beta blockers are at least as effective as the other drugs but have less side effects. There is no clear choice between the other drugs but if dual therapy does not give adequate control of symptoms there is no benefit from adding a third.
• When used without a beta blocker, diltiazem, or modified release nifedepine may be used. Verapamil is at high risk of inducing bradycardia or congestive heart failure and is best avoided. The risk of bradycardia with diltiazem plus beta blocker is also significant.
• Unless there is contraindication, aspirin and a statin should be started. Clopidogrel is an alternative for those who cannot take aspirin but it is much more expensive. Aspirin may be used at doses of 75-300mg daily. The evidence for the optimum dose is inconclusive in terms of risk:benefit and it is best to follow local protocols. Most people with angina are prescribed 75 or 150mg.
• All patients with stable angina should be considered for treatment with an ACE inhibitor.³

Coronary revascularisation

• Coronary revascularisation is required in those at high risk and those who have failure to be controlled by medical therapy.
• A cardiac rehabilitation programme should be arranged following revascularisation.³
• Both coronary artery bypass grafting and percutaneous transluminal angioplasty have their indications and advocates.
• For the low risk patient with stable angina, medical management carries the lowest risk.

Management of cardiovascular risk factors

• Cessation of smoking is imperative.
• Advice may be needed about weight reduction, healthy eating, reduced alcohol consumption and exercise. Exercise should be encouraged but the patient must not exercise through the pain of angina. If the exercise regime is started after the stress test, the exercise tolerance is known.
• Statins should be prescribed for all patients with stable angina due to atherosclerotic disease, unless contraindicated.³
• Optimal glucose control in people with diabetes should be achieved.
• LDL-cholesterol should be brought down below 3.0 or by 25 to 30% of the baseline level, whichever produces the lower level. Even with statins, diet must not be ignored. There may be further benefit from more aggressive lipid lowering.
• Optimal management of hypertension. If there is no contraindication, beta blockers may be the best choice as they reduce myocardial oxygen consumption and so can reduce angina, even without hypertension.

• Recognition of possible myocardial infarction and calling an ambulance without delay.
• Not to stop beta blockers suddenly as there is a risk of rebound angina.
• Controlled angina is not a bar to driving and the DVLA do not have to be notified but the insurer should know or the insurance may be invalid. LGV and PSV drivers must inform the DVLA and forfeit their special licences.
• Those who can briskly climb a couple of flights of stairs should manage sexual intercourse but nitrates and nicorandil may cause undue hypotension if taken with sildenafil or related drugs.
• In general, those with stable angina who can climb 12 stairs and walk 50 metres on the level without severe breathlessness and without developing angina are fit to fly as passengers.
• Even if there is proven cardiac chest pain, the patient can also experience non-cardiac chest pain but often interprets this as symptoms of heart disease. It is important to distinguish between the two causes to reduce levels of distress, and avoid inappropriate use of medical treatments.

• 1 patient in 10 will suffer a non-fatal or fatal myocardial infarction within a year of diagnosis.⁶
• This is not a benign condition and it must receive energetic and evidence based treatment.