Overview

What is angina?

Angina is a chest pain caused by a reduced amount of oxygen-rich blood flowing to your heart muscle, which is usually caused by coronary artery disease. Angina can be a warning sign of both a heart attack and stroke, therefore early diagnosis and management is crucial to prevent these from occurring. 

Typical angina is described as experiencing a tightness, heaviness or pressure-like feeling in your chest. The symptoms typically affect a broad area of your chest, rather than one precise spot. Your symptoms may present as being more severe when you are doing physically demanding tasks, such as exercising (including walking) or lifting a heavy object. However, the symptoms will subside when you stop the task or if you take a prescribed medication from your doctor called glyceryl trinitrate.¹

How could an angina diagnosis potentially save your life?

When you receive a diagnosis of angina this can be very distressing, however, this diagnosis could potentially save your life as angina is a warning sign of much more serious conditions, such as a heart attack. 

A heart attack is when one of the coronary arteries, which provide your heart muscle with oxygen-rich blood, becomes blocked by a blood clot, meaning that your heart muscle is starved of oxygen, which is needed for its survival. 

Therefore proper management of your angina through recommended lifestyle changes, and medication prescribed by your doctor, can help to reduce the risk of developing more serious health conditions.

How can beta blockers aid in the treatment of angina?

Beta blockers lower the oxygen demand of your heart and this in turn reduces how many angina attacks you are having. This can relieve the symptoms associated with angina, such as chest pain.²

Understanding beta blockers

How do beta blockers work?

Beta blockers work by preventing the stress hormones adrenaline and noradrenaline from affecting your body. This in turn prevents your body from acting how it would in a state of stress, where you would expect your heart to beat rapidly. Instead, your heart rate will start to slow down.

In addition, beta blockers also prevent your kidneys from releasing a hormone known as angiotensin II, which lowers your blood pressure. Beta blockers also help to widen your blood vessels, increasing the amount of blood that flows through your arteries and veins, and thus the amount of oxygenated blood flowing to your heart muscle.

Beta blockers elicit these effects by binding to beta receptors in your body. Beta receptors work by having a chemical or hormone bind to them that fits perfectly into the receptor, similar to how a key fits into a lock. Therefore a hormone such as adrenaline can bind to a beta receptor and cause a state of stress by rapidly increasing your heart rate. 

Beta blockers work as ‘antagonists’, meaning that they can also bind to a beta receptor, similar to a lock and key model, but this stops adrenaline from binding to beta receptors and having an effect on your body.

What are the different types of beta blockers?

Beta blockers are categorized as being either ‘selective’ or ‘non-selective’.³

Selective beta blockers

Selective beta blockers work by just blocking beta receptors in your heart muscle, stopping adrenaline and noradrenaline from affecting your heart, and rapidly increasing your heart rate. These receptors are known as beta-1 (B1) receptors.³ 

Non-selective beta blockers

Non-selective beta blockers do not just stop adrenaline and noradrenaline from having an effect on your heart but also in other areas of the body. This is because non-selective beta blockers bind to B1 receptors (which are found in the heart muscle), and beta-2 (B2) receptors which are found in other areas of your body, such as your airway smooth muscle. 

This means that these types of beta blockers stop the stress hormones from having effects on both your heart and other areas of your body.³ 

How do beta blockers reduce angina symptoms?

Beta blockers reduce the workload of your heart by. Lowering the oxygen demand of your heart. It also dilates your arteries allowing more oxygen-rich blood to flow to your heart. 

This ensures that the symptoms associated with angina, including heaviness and chest pain, are relieved as these are caused by the heart not receiving enough oxygenated blood.¹

Indications for beta blockers in angina

The two different types of angina are as follows:

• Stable angina
• Unstable angina

What is stable angina?

Stable angina is characterized as having the following:

• A chest pain or angina attack that occurs when you are doing exercise or suffering from emotional stress
• The symptoms of angina are relieved when you rest or take a medication known as glyceryl trinitrate

Why are beta blockers suitable for stable angina?

Beta blockers prevent the beta receptors in your heart from being activated by stress hormones, which in turn reduces the oxygen demand of the heart. This helps to relieve the symptoms you experience during an angina attack, such as chest pain.⁴

What is unstable angina?

Unstable angina is when your symptoms develop unpredictably, unlike stable angina where they occur during exercise or emotional distress. In addition, unlike stable angina, you will be prescribed the following medication to prevent blood clots from developing:

• Low-dose aspirin
• Clopidogrel
• Ticagrelor

Role of beta blockers in acute situations

Beta blockers have the potential to be very beneficial if you have an acute heart attack.  Beta blockers will decrease the oxygen demand and workload of your heart by reducing your heart rate and blood pressure. This in turn relieves any chest pain you may be experiencing.⁵

Effectiveness and benefits

Symptom relief and reducing oxygen demand for your heart

One of the key benefits of taking beta blockers for your angina is the reduction in the oxygen demand for your heart, which can in turn relieve your symptoms, such as chest pain. ⁴

Long-term benefits in angina management

Long-term benefits of taking beta blockers when you have been diagnosed with angina include the following:

•  A reduction in the amount of angina attacks
• Decrease the risk of death compared to having no treatment ⁴
• Reduce the risk of developing unstable angina compared to having no treatment ⁴

Considerations and contraindications

When might beta blockers be an unsuitable treatment for angina?

Sadly beta blockers are not an ideal treatment for everyone when it comes to angina, and you may not be prescribed beta blockers for your angina if you have one of the following:

• History of an allergic reaction to a beta blocker or other type of medication
• Low blood pressure
• Too much acid in your blood
• Asthma
• Uncontrolled heart failure
• Lung diseases

Potential side effects

The following adverse side effects can occur if you start taking beta blockers:

• Bradycardia
• Hypotension
• Fatigue
• Nausea
• Constipation
• Dizziness
• Erectile dysfunction ²

Contraindications and precautions

Beta blockers should not be used if you suffer from one of the following:

• Severe peripheral arterial disease or Raynaud’s syndrome
• If you suffer from hypoglycaemia frequently
• Asthma
• Clinically significant hepatic dysfunction
• Severe heart failure
• If you are intolerant/allergic to beta blockers

Beta blockers can be prescribed by your doctor, with caution, if you suffer from one of the following conditions:

• Chronic obstructive pulmonary disease (COPD)
• Diabetes mellitus
• Psoriasis
• Myasthenia gravis
• Hypotension
• Less severe peripheral artery disease
• If you are a contact lens wearer
• History of hypersensitivity to allergens

Please note that the above lists in this section are not exhaustive.

Dosage and administration

Monitoring and adjustments

Both your heart rate and blood pressure needs to be monitored whilst you are on a course of beta blockers to ensure they are having their desired effect on your body. 

According to your doctor’s suggestion your pharmacist will dispense your beta blocker medication and ensure that the dose of the beta blocker is correct.² Your dose may be adjusted if you develop certain conditions such as renal disease.⁶

Combination therapies with beta blockers

In order to treat angina you may be prescribed a medication known as calcium channel blockers, in conjunction with beta blockers. 

Calcium channel blockers reduce the amount of calcium entering the cells in the heart and the walls of your blood vessels. Calcium causes your blood vessels to contract, reducing the amount of blood flowing through them to the heart. Calcium channel blockers prevent this from occurring, meaning that more oxygenated blood can flow to your heart.

It is important to note that beta blockers do not provide immediate relief of angina symptoms, and for immediate relief of symptoms you will have to take another medication known as glyceryl trinitrate.

Summary

Angina is a chest pain that occurs when your heart muscle is not receiving enough oxygen-rich blood. During an angina attack there can be a feeling of heaviness, tightness or pressure in the chest. The disease can be categorized as either stable angina or unstable angina.

For treating angina beta blockers are prescribed. They reduce the workload of your heart, meaning that there is less oxygen demand. Additionally, they lower your blood pressure and heart rate, and aid in relieving the symptoms of angina.

Beta blockers works by blocking the beta receptors in your body, which are responsible for binding stress hormones such as adrenaline and noradrenaline, allowing these stress hormones to have an effect on your body by increasing your heart rate and blood pressure.

Beta blockers can be selective or non-selective. They are typically prescribed if you have stable angina or are suffering from an acute condition, such as a heart attack. However, if you develop an allergic response to the medication or have other symptoms, calcium channel blocker may also be advised.

Immediate relief of angina symptoms can only be achieved by taking glyceryl trinitrate if your doctor deems it necessary.