How to diagnose and treat angina - The basics

An average GP will see four new cases of angina a year, says Dr Louise Warburton.

The prevalence of angina in the UK is 9.2 per cent in men aged 55-64 and 16.2 per cent for men aged 65-74.

There are two types: stable angina and unstable angina, or acute coronary syndrome, when symptoms are due to the more severe changes of arterial wall plaque erosion and rupture.

Angina is graded in severity.

Several characteristics of stable angina increase the likelihood of underlying CHD: when discomfort is described as dull, tight or heavy; pain is felt retrosternally to the left side of the chest, radiating into the left arm, neck or jaw; pain is brought on by exertion or emotional stress; symptoms last several minutes after exertion but then disappear; and can be precipitated by cold weather or a meal.

DIAGNOSTIC TESTS
A baseline ECG should be carried out on every patient with suspected angina; this could show AF or left ventricular hypertrophy.

An abnormal exercise ECG, with changes including ST depression requires further investigation.

Myocardial perfusion scintigraphy with exercise or pharmacological stress reliably predicts the presence of CHD.

This may be the investigation of choice in those patients with pre-existing ECG abnormalities such as left bundle branch block.

Coronary angiography is the benchmark investigation for establishing the nature, anatomy and severity of CHD.

However, as it is invasive and carries a risk of death, it should be reserved for patients identified as high risk or where a diagnosis remains unclear.

Guidelines suggest that patients with suspected angina should be referred to a chest pain evaluation service.

DRUG THERAPY
Beta-blockers should be used first-line for the relief of symptoms of stable angina and long-term prevention of chest pain. Usual regimens are atenolol 100mg daily, metoprolol 50-100mg two to three times daily or bisoprolol 5-20mg daily.

Rate-limiting calcium channel blockers such as verapamil and diltiazem have restricted use in angina patients with heart failure, bradycardia or atrioventricular block.

Patients with angina and heart failure may safely be treated with amlodipine or felodipine. The same applies to patients with Prinzmetal's angina.

Sublingual glyceryl trinitrate is effective for the immediate relief of angina and can be used to prevent ischaemic episodes when taken before planned exertion.

Nicorandil is a potassium channel activator that is as effective as amlodipine and diltiazem in treating angina.

PREVENTION
Various trials have shown a benefit of statins for stable angina, with significant reductions in all-cause and coronary mortality and the need for coronary revascularisation.

Antiplatelet therapy will significantly reduce serious vascular events, non-fatal MI and stroke.

Though there is conflicting evidence about the use of ACE inhibitors in stable angina, they are beneficial if there is left-ventricular dysfunction or heart failure.

ACUTE CORONARY SYNDROME
Angina of increasing frequency and severity is termed unstable angina.

There is increased risk if any of the following are present: rest angina of more than 20 minutes; ECG changes, pulmonary oedema, hypotension or tachycardia; MI in the past 14 days; and elevated serum troponin levels.

Patients with any of these risk factors should be referred to a cardiologist.

Dr Warburton is a GP in Ironbridge, Shropshire

GRADES OF ANGINA SEVERITY

Class I: ordinary activity such as walking or climbing stairs does not precipitate angina.

Class II: angina is precipitated by emotion, cold weather, meals or by walking upstairs.

Class III: there are marked limitations of normal activity.

Class IV: inability to carry out physical activity without discomfort and symptoms may be present at rest.

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