Stable Angina

Introduction

Angina is a clinical syndrome of chest pain/pressure that accompanies transient myocardial ischaemia (but does not injure the myocardium). It usually results from coronary artery disease and is exacerbated by activities that increase myocardial demand for oxygen e.g. exercise, stress. Diagnosis is mostly based on clinical history.

Epidemiology

Affects 1% of the population and accounts for 3% of all hospital admissions. Affects men more than women.

Causes

Either a reduction in blood flow or an increase in oxygen demand. The commonest cause is atherosclerotic coronary artery stenosis. Other causes include thrombus formation on a plaque, artery spasm, tachycardia and anaemia.

Precipitants

Common:

• Physical exertion
• Cold exposure
• Heavy meals
• Intense emotion

Uncommon:

• Lying flat
• Vivid dreams

Risk factors

• Male
• Smoking
• Obesity
• Diabetes
• Hypertension
• Hyperthyroidism
• Hypercholesterolaemia
• Anaemia
• Family history

Types

Stable angina

Pain is provoked by physical exertion or cold, windy weather. It is relieved within 2-10 minutes of rest. Note that the severity of pain is not related to the degree of coronary artery disease.

Nocturnal angina

Occurs at night and may wake the patient from sleep. It can be provoked by vivid dreams. It tends to occur in patients with critical coronary artery disease.

Decubitus angina

Occurs when lying down. Usually occurs as a complication of heart failure as a result of severe coronary artery disease.

Variant/Prinzmetal’s

Caused by focal spasm of normal coronary arteries, usually at rest. 75% of patients also have atherosclerotic coronary artery obstruction. Chest pain may occur at rest and accompanied by dyspnoea and/or palpitations. Diagnosis may be made on a characteristic ECG, which shows transient ST elevation.

Unstable angina

Considered a part of acute coronary syndrome. Refers to any of:

• Angina of recent onset (<1 month)
• Worsening angina
• Angina on rest

Pathophysiology of pain

Pain is stimulated by metabolic products of ischaemia, which pass to the sympathetic ganglion between C7 and T4. The pain is then referred to peripheral dermatomes.

Clinical features

Typical symptoms

Anginal pain is characteristically a constricting discomfort in the front of the chest, or in the neck, shoulder, jaw or arms. It is precipitated by physical exertion and relieved by rest or glyceryl trinitrate (GTN) within 5 minutes. Characteristics of the pain include:

Site: Retrosternal or left side of chest

Onset: Gradual

Character: Tight, dull, heavy

Radiation: Neck, shoulder, jaws, arm (usually inner part of left arm)

Aggravation: Exertion, emotional stress

Alleviation: Rest, GTN

Timing: Usually lasts for 2-10 minutes

Atypical symptoms

Usually seen in women, older patients and diabetic patients.

• Dyspnoea
• Nausea and vomiting
• Restlessness
• Dizziness
• Tachycardia
• Sense of impending doom

Signs

The examination is usually unremarkable. However, there may be signs of risk factors. These can include:

• Smoking: tar staining
• Hyperthyroidism: tachycardia, tremor, goitre
• Hypercholesterolaemia: xanthelasma, tendon xanthoma
• Anaemia: pallor
• Diabetes: neuropathy, retinopathy

Diagnosis

Angina is usually diagnosed based on clinical history. Anginal pain has 3 characteristics:

1. Constricting discomfort in chest or neck, shoulders, jaw or arms
2. Precipitated by exertion
3. Relieved by rest or GTN within 5 minutes

All 3/3 of the above are typical. 2/3 are atypical. 1/3 should be considered non-anginal. Also take into account the patient’s background (e.g. age, risk factors). If anginal pain does not resolve within 5 minutes of GTN, consider a diagnosis of unstable angina.

Investigations

Blood tests: required for all patients, most importantly FBC (checking for anaemia), thyroid tests (checking for hyperthyroidism) and troponins (to exclude infarction). ECG: used if angina cannot be diagnosed or excluded clinically. Demonstrates ST depression if there is ischaemia. However, a negative finding does not exclude angina. ECG findings are normal between attacks. An exercise ECG can be used to better diagnose angina. If the diagnosis is still uncertain, further investigation to consider include angiography (if revascularisation is being considered), stress echocardiography and MRI.

Management

Acute attacks

1. Stop precipitating factor (e.g. exercise)
2. Sublingual GTN; advise patients to spit out the tablet as soon as pain is relieved to avoid side-effects (e.g. headache)

Chronic angina

Lifestyle:

• Exercise
• Stop smoking
• Weight control

Drugs:

• Symptomatic: Short-acting GTN
• Antianginal drugs: Offer either beta-blockers (e.g. metoprolol) or calcium channel blockers (e.g. amlodipine). Use both if one alone has little effect. Second-line drugs include long-acting nitrates, ivabradine and nicorandil.

Surgery: If medical therapies are inadequate, consider coronary artery bypass graft (CABG) or percutaneous coronary intervention (PCI).

Prognosis

Annual mortality is 2-3%. Stable and mild angina has a 8-year survival of 90%.