Angina pectoris, commonly known as angina, is the occurrence of chest pain as a result of restricted blood supply to the muscles of the heart. The most common form of angina occurs as a result of Coronary Artery Disease (CAD), a disease caused by the build up of plaque on arterial walls that reduces blood flow to the heart itself. The hardening and narrowing of the arteries is known as artherosclerosis.

There are two types of angina 

• Stable angina is characterised by angina attacks that occur due to obvious triggers (like exercise). They improve with medication and rest.
   
• Unstable angina results in more unpredictable angina attacks, with no obvious trigger and no alleviation from symptoms despite resting. Stable angina is indicative of an increased risk of life threatening illnesses such as heart attack or stroke. Unstable angina is often regarded as a medical emergency, as it is often a sign that the heart has rapidly deteriorated.

Other cardiac abnormalities are risk factors for angina 

• Diseases characterised by outflow obstruction, such as aortic stenosis (a narrowing of the aortic valve) or hypertrophic obstructive cardiomyopathy (a thickening of the heart muscle without any obvious cause), are particularly high risk factors.

Most common treatments for Angina

People with angina often take medicines to reduce the risk of heart attack and stroke:

Statins block the effects of an enzyme in the liver that has a role in the development of cholesterol. This reduction in cholesterol can subsequently prevent further damage to the coronary arteries, reducing the risk of heart attack and stroke in the process.

Angiotensin-converting enzyme (ACE) inhibitors improve blood flow by blocking the activity of hormone called angiotensin II. As they have also been known to reduce the supply of blood to the kidneys, blood and urine tests must also be carried out prior to use to ensure
there is no underlying kidney condition.

Low-dose aspirin is an antiplatelet medication that prevents blood clots and reduce cardiovascular and stroke risks

The purpose of angina treatment

The purpose of angina treatment is to:

• relieve symptoms during attacks
• reduce the number of attacks
• reduce the risk of any future complications

For many patients, this is often prescribed in conjunction with wider lifestyle changes related to diet and exercise.

The most common combination treatments include a statin that lowers cholesterol levels, a beta-blocker to protect the heart and prevent pain associated with angina, and an aspirin to help prevent a heart attack. Occasionally, an ACE inhibitor medicine is prescribed.

Stable angina

For stable angina, there are some medicines available that help to alleviate associated pain.

Angina symptoms will usually stop within 1-2 minutes if a patient takes glyceryl trinitrate, which is designed to provide immediate relief. It helps to reduce the frequency and severity of attacks by relaxing blood vessels and reducing the amount of work that the heart must undertake to pump blood around the body (1). It is also commonly used in surgical procedures to safely lower blood pressure, and can be dissolved under the tongue in tablet form or as an oral spray.

Longer term treatments often involve the use of a beta blocker such as atenolol or propranolol. There is a substantial body of evidence to support the use of such medication in angina treatment, with many studies highlighting their role in reducing the number and severity of symptoms, increasing life expectancy, and improving quality of life.

Beta blockers are often used in conjunction with inhibitors such as Ivabradine, with evidence suggesting that combination treatment is more efficacious than beta blockers administered on their own (2).

Ivabradine has been evidenced to significantly reduce angina symptoms, particularly in older populations: a retrospective study of clinical trials involving 2500 participants in Germany, all aged over 75, found a marked improvement in the reduction of angina symptoms and significant increase in self-reported quality of life (3).

Many vasodilators (drugs that widen the blood vessels) are used in angina treatment including nifedipine, nicorandil, isosorbide mononitrate and amlodipine. They are all calcium channel blockers and relax the muscles on the walls of the arteries, allowing increased blood flow to the heart.  

ACE inhibitors are also vasodilators with a firm evidence base regarding their safety and efficacy (4).

The wide variety of medications available for the treatment of angina ensures that there is often a treatment option, or combination of treatments, for patients who cannot take certain drugs due to existing medical problems.

• Ivabradine has a similar effect to beta blockers for those who are unable to take them, such as people with lung infections.
• Potassium channel activators such as nicorandil can be used for patients who cannot take calcium channel blockers.
• Long acting nitrates are frequently used in treatment, but they should never be taken in conjunction with the erectile dysfunction treatment sildenafil as they interact and cause a dangerous drop in blood pressure (5).
• For angina sufferers who also have irregular heartbeats, ranolazine relaxes the muscles of the heart to improve blood flow whilst not affecting the speed at which the heart beats (6).

If combination therapy doesn’t work, at this point patients will often be considered for a surgical procedure.

Modifiable risk factors for angina

Many of the contributory factors to angina are modifiable and lifestyle related, so having a healthy lifestyle is the most effective way of reducing risk.

This consists of:

• eating a healthy balanced diet
• keeping blood pressure at a stable level
• avoiding smoking
• reducing alcohol consumption
• plenty of regular exercise

These measures also reduce the risk of other non communicable diseases such as diabetes mellitus, hypertension and obesity, all of which also increase the risk of angina and other heart related complications.

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References

1. Jones M, Rait G, Falconer J, et al. (2006). Systematic review: prognosis of angina in primary care. Fam Pract 23(5):520-8

2. Ageeva FT, Makarova GV, Patrusheva IF, Orlova IA. (2010). The efficacy and safety of the combination of β-blocker bisoprolol and if inhibitor I (f) ivabradine in patients with stable angina and chronic obstructive pulmonary disease. Kardiologiia 50(10):22-6

3. Muller-Werdan U, Stockl G, Ebelt H, Nuding S, Hopfner F, Werdan K. (2014). Ivabradine in combination with beta-blocker reduces symptoms and improves quality of life in elderly patients with stable angina pectoris: Age-related results from the ADDITIONS study. Exp Gerontol 59C:34-41

4. Siama K, Tousoulis D, Papageorgiou N, Siasos G, Tsiamis E, Bakogiannis C, Briasoulis A, Androulakis E, Tentolouris K, Stefanadis C. (2013). Stable angina pectoris: current medical treatment. Curr Pharm Des 19(9):1569-80

5. Ghofrani HA, Osterloh IH, Grimminger F. (2006). Sildenafil: from angina to erectile dysfunction to pulmonary hypertension and beyond. Nat Rev Drug Discov 5(8):689-702

6. Belsey J, Savelieva I, Mugelli A, Camm AJ. (2014). Relative efficacy of antianginal drugs used as add-on therapy in patients with stable angina: A systematic review and meta-analysis. Eur J Prev Cardiol  pii: 2047487314533217 [Epub ahead of print]