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Stable Angina

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Overview

Angina describes chest pain or discomfort in the chest, neck, shoulders, jaw, or arms due to an insufficient blood supply to the heart muscle. It is usually caused by atherosclerosis – where arteries are narrowed due to fatty plaques. Angina can also be caused by valvular disease, hypertrophic obstructive cardiomyopathy, or hypertensive heart disease.

Stable and unstable angina

Angina is said to be stable if it occurs predictably with physical exertion or emotional stress, does not last for more than 10 minutes, and is relieved with rest and the use of sublingual nitrates.

Unstable angina describes a sudden worsening in angina occurring at rest and requires immediate hospital admission. It should be managed as a form of acute coronary syndrome.

Epidemiology

  • Coronary heart disease is the single most common cause of death in the UK
  • Prevalence increases with age for both men and women
  • People of South Asian origin have an increased risk
  • Around 8% of men and 3% of women aged 55-64 years currently have angina

Risk Factors

  • Increased age
  • Smoking
  • Hypertension
  • Elevated LDL cholesterol
  • Diabetes mellitus
  • Obesity
  • Illicit drug use
  • Inactivity
  • Male sex
  • Cardiac abnormalities e.g. aortic stenosis/hypertrophic obstructive cardiomyopathy

Presentation

The typical presentation of angina has 3 characteristics:

  1. The pain is crushing or squeezing
    1. This may be central and may radiate to the jaw or arms
  2. The pain is provoked by exercise or emotional stress
  3. The pain is relieved by rest or using glyceryl trinitrate (GTN)

Atypical angina has only 2 of the 3 features, meaning they may not have any chest pain at all. It is usually seen in:

  • Women
  • People with diabetes
  • The elderly

Differential Diagnoses

Acute coronary syndrome

Pulmonary embolism (PE)

  • Acute shortness of breath and pleuritic chest pain
  • Tachypnoea and tachycardia are present
  • There may be a swollen calf
  • There may be risk factors for the development of PE such as recent surgery, prolonged immobilisation, long-haul flights, malignancy, combined oral contraceptive pill use, oestrogen-containing oral hormone replacement therapy

Pericarditis

  • Acute severe retrosternal pleuritic chest pain that is worse when lying down and improves when leaning forward or sitting upright
  • A pericardial friction rub may be heard on examination
  • ECG shows global saddle-shaped ST-elevation and PR depression

Pneumothorax

  • Acute shortness of breath and cough with chest pain
  • Decreased breath sounds and hyperresonance are seen on examination

Gastro-oesophageal reflux disease (GORD)

  • Epigastric pain that may radiate to the throat
  • Symptoms are relieved with antacids
  • There may be trigger foods (e.g. coffee)

Peptic ulcer disease

  • Epigastric pain that may radiate to the back
  • Gastric ulcers are worse when eating food
  • Duodenal ulcers improve when eating food

Costochondritis

  • Pain at one of the costochondral or costosternal junctions that is reproduced on palpation

Biliary colic

  • Episodic right upper quadrant pain that occurs around 30 minutes after eating a meal lasting for up to 4 hours
  • Aggravated by eating fatty foods
  • Associated with bloating, nausea, and vomiting

Investigations

Overview

  • Resting ECG:
    • All patients with suspected ischaemic heart disease should have an ECG to rule out acute coronary syndromes
    • These are usually normal or may show signs of a previous myocardial infarction. This shows up as pathological Q waves.
  • Haemoglobin:
    • Anaemia can cause angina due to a reduced oxygen supply being insufficient for the demands of myocardial tissue.
  • Lipid profile:
    • Dyslipidaemia is a risk factor
  • Fasting blood glucose or HbA1c:
    • Diabetes mellitus is a risk factor
  • CT coronary angiogram:
    • This is the diagnostic test which shows luminal narrowing

Management

All patients

All patients should be given aspirin and a statin (as long as they are not contraindicated) and are given sublingual GTN spray (to stop acute attacks) and a drug to provide long-term relief from symptoms (discussed below).

Patients are also recommended the annual influenza vaccine.

Acute attacks of anginal symptoms

  • Glyceryl trinitrate (GTN spray) for symptom relief:
    • When an angina attack happens:
      • Stop what they’re doing and rest
      • Use GTN spray then wait 5 minutes
      • Take a second dose of GTN spray then wait 5 minutes
      • If the pain persists 5 minutes after the second dose, call 999
    • Concurrent phosphodiesterase-5 (PDE-5) inhibitors (e.g. sildenafil or Viagra) are contraindicated as they both can cause hypotension

Long-term relief of anginal symptoms

  • 1st-line: beta-blockers or calcium channel blockers (CCBs)
    • Beta-blocker options: bisoprolol, carvedilol, metoprolol
    • Calcium channel blocker options:
      • If monotherapy then rate-limiting CCBs: verapamil or diltiazem
      • If combined with beta-blockers: nifedipine or amlodipine
        • Never combine beta-blockers with rate-limiting calcium channel blockers (such as verapamil and diltiazem). This can cause severe bradycardia 
  • 2nd-line: if one fails to work, try the other or switch to a combination
    • Never co-prescribe rate-limiting CCBs (i.e. verapamil or diltiazem) with bisoprolol as there is a risk of profound bradycardia and a complete heart block.
  • 3rd-line: depends on what the patient is taking
    • If the patient is taking monotherapy (beta-blocker/CCB) and cannot tolerate addition of another 1st-line drug: offer one of the other anti-anginal drugs (discussed below)
    • If the patient is taking both a beta-blocker and CCB, refer for revascularisation via percutaneous coronary intervention (PCI) or a coronary artery bypass graft (CABG) and offer one of the other anti-anginal drugs (discussed below)

Other anti-anginal drugs

These drugs are considered if:

  • Beta-blockers and CCBs are both contraindicated
  • The patient is taking a beta-blocker or CCB and cannot tolerate the addition of the other CCB or beta-blocker
  • The patient is taking a beta-blocker and CCB and is awaiting an assessment in secondary care for a PCI or CABG

These drugs include:

  • Long-acting nitrates e.g. isosorbide mononitrate
    • Some patients develop nitrate tolerance, meaning their symptoms return and treatment is less effective. To overcome this, the dosing intervals should be asymmetrical.
    • This effect is not seen in people who take once-daily modified-release isosorbide mononitrate
  • Ivabradine
  • Nicorandil
    • PDE-5 inhibitor use (such as sildenafil, Viagra) is contraindicated.
  • Ranolazine

Anti-Anginal Drugs

Nitrates

Nitrates are drugs that have vasodilating effects. They are mainly used in the management of angina and heart failure. They work by activating guanylate cyclase which converts GTP to cGMP which reduces intracellular calcium ion levels and vasodilation.

Examples of nitrates are:

  • Sublingual glyceryl trinitrate (GTN spray): used to abort acute angina attacks
  • Isosorbide mononitrate: for the prophylaxis of angina

Key side effects of nitrates are:

Some patients taking long-acting nitrates may develop nitrate tolerance, leading to decreased effectiveness. Reducing the blood nitrate concentration to low levels for 4-12 hours a day usually reduces the risk of this occurring. Patients should take the second dose of the long-acting nitrate after 8 hours rather than 12 hours. This allows the nitrate levels to fall for 4 hours and reduces the risk of tolerance.

Contraindications include:

Ivabradine

Ivabradine reduces the heart rate by selectively binding to If (‘funny channels’), disrupting ion flow and prolonging diastolic depolarisation, slowing the heart rate. The If channels are mainly found I the sinoatrial node (SAN), therefore ivabradine reduces heart rate by lowering the SAN firing rate.

Key side effects of ivabradine are:

  • Visual disorders – phosphenes and green luminescence
  • Arrhythmia – bradycardia
  • Heart block
  • Headaches
  • Dizziness

Contraindications include:

Nicorandil

Nicorandil is a potassium channel activator that relaxes vascular smooth muscle via membrane hyperpolarisation due to increased potassium ion conductance and increased concentrations of cGMP.

Key side effects include:

  • Headaches
  • Flushing
  • Vomiting
  • Ulceration – including the skin, mucosa, eyes, gastrointestinal tract, and anal ulcers

Contraindications include:

  • Acute left ventricular failure
  • Acute pulmonary oedema
  • Severe hypotension
  • Shock

Ranolazine

The mechanism of action of ranolazine is not fully understood. It reduces the oxygen demand of the heart.

Key side effects include:

  • QT prolongation
  • Constipation
  • Headaches
  • Vomiting

Monitoring

  • Patients should be regularly followed up for changes in symptoms along with looking for complications such as heart failure or arrhythmia
  • If a patient has new or worsening angina, you must determine whether the patient can be managed safely as stable angina or needs management as an acute coronary syndrome

Patient Advice

  • Patients should stop smoking and manage their risk factors e.g. obesity, diet
  • Patients should continue to carry out their activities of daily living and be educated on using the GTN spray appropriately
  • Patients should be safety-netted on when to seek emergency help when using a GTN spray

Complications

  • Myocardial infarction
  • Stroke
  • Unstable angina
  • Sudden cardiac death
  • Peripheral arterial disease

Prognosis

  • Appropriate lifestyle changes and medical intervention can lead to more than half of people with angina being symptom-free within 1 year
  • Stable angina is a chronic medical condition with a risk of progressing to acute coronary syndrome

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