Introduction 

Have you ever felt your pulse to see how fast your heart is beating or in what pattern? Have you ever been told you have an irregular heartbeat? Perhaps you have atrial fibrillation, one of the most common heart rhythm disturbances.¹

Atrial fibrillation is when the heart has irregular contractions that lead to inefficient circulation of blood. This can increase the risk of blood clots forming within blood vessels, which can result in a stroke if it reaches the brain. Therefore, medications that prevent clot formation (anticoagulants) may be recommended to reduce your risk of stroke.

How does the heart work?

The heart usually beats in a regular rhythm, typically at a speed of 60 to 100 beats per minute at rest.^1,2 This varies with changes in physical activity, fitness and sleep.² 

The heart is made up of four compartments, a left and right atrium on top and a left and right ventricle below.³ Blood passes from the atria to the ventricles. The right side of the heart is responsible for sending blood to the lungs to collect oxygen. This blood then goes to the left side of the heart which pumps the oxygenated blood to the rest of the body. Valves are located between compartments and act like doors to stop blood flowing in the wrong direction.

The heart has its own natural pacemaker (the sino-atrial node), which sends electrical signals to the atria and ventricles to ensure they contract at a regular rate and in the correct order.³ This ensures the heart effectively fills with blood before it is pumped around the body. Any changes to the functioning of the atria, ventricles or valves can lead to inefficient blood flow throughout the body.

What is atrial fibrillation?

Atrial fibrillation (AF) is one of the most common heart rhythm conditions and involves the heart beating irregularly.¹ In AF, part of the atria produces abnormal electrical signals which take over control from the natural pacemaker. This results in irregular and random contractions of the atria and therefore inefficient pumping of the blood around the body.¹ There are different descriptions of AF based on how long it lasts:¹

• Paroxysmal AF – Intermittent and the heart is in a normal rhythm between episodes
• Persistent AF – Lasts longer than a week
• Permanent AF – Present all of the time
• Long-standing AF – Present for over a year

What are the symptoms of atrial fibrillation?

AF can often be asymptomatic, and many people do not know they have AF until it is picked up incidentally with other medical investigations. Symptoms of AF may include:^1,4

• Palpitations – feeling the heart beating out of rhythm
• Fast heart rate 
• Fainting
• Shortness of breath
• Fatigue
• Chest discomfort

How is atrial fibrillation diagnosed?

AF is diagnosed by feeling an irregular pulse on the wrist or the neck. An electrocardiogram (ECG) can give a more detailed analysis of the heart rate and rhythm.¹ This investigation involves stickers on the chest (electrodes) connected to leads and a monitor to show the heart's rhythm. A scan of the heart, an echocardiogram (echo), can show more detail on structural changes to the heart and blood flow.⁵ This could show what is causing the irregular heartbeat, such as a problem with a valve.

What are the risk factors for atrial fibrillation?

Certain risk factors for atrial fibrillation have been identified:^1,6

• Increasing age
• High alcohol consumption
• High blood pressure
• Being overweight
• Smoking

What is the treatment for atrial fibrillation?

It is important that AF is treated, as it can lead to stroke and heart failure if untreated.¹ AF can be treated with a broad approach and the specific treatment will vary on an individual basis:^1,4

• Lifestyle guidance, such as reducing alcohol and drug consumption
• Anticoagulation – to thin the blood to reduce the risk of stroke
• Rate control medication – to slow down the heart if it is beating too fast e.g diltiazem or verapamil
• Rhythm control medication – to control the rhythm of the heart
• Atrial ablation – to destroy the tissue that causes the irregular heart rhythm
• Pacemaker insertion – to maintain a regular rate of contraction in the heart

What are the options for anticoagulation?

Anticoagulants are medications used to prevent clots from forming in the blood. Clots are more likely to form in AF, as the heart is not working as efficiently to move blood around the body.⁷ If a clot breaks free and then travels toward the brain it could result in a stroke. A stroke is where the blood supply to the brain is cut off, preventing oxygen and nutrients from reaching the brain, and resulting in damage to brain tissue.^1,8 A stroke can cause loss of sensation, difficulty moving and difficulty with speech. The risk of a stroke also increases with high blood pressure, diabetes, high cholesterol and increased age.^1,8 

Anticoagulation can therefore be an important part of AF treatment for most people, but the benefits need to be considered against the risks.⁴ The two main medications given for anticoagulation are called direct oral anticoagulants (DOACs) and warfarin.

DOACs

DOACs are newer medications that work on the clotting pathway to reduce the speed of clotting. DOACs include apixaban, rivaroxaban and dabigatran, which are all oral medications. The advantage of DOACs is they require less monitoring with blood tests and dose adjustments. They do not often require changes in diet, in comparison to warfarin whichdoes.^4,8

Warfarin

Warfarin also works to reduce the speed of blood clotting. Warfarin needs to be monitored by regular blood tests to make sure the right dose is given. Diet can affect how warfarin works and therefore you will be unable to drink grapefruit juice or cranberry juice and will need to avoid alcohol.¹ This is because they can affect the levels of warfarin, which can increase the risk of bleeding. 

Anticoagulants can cause a variety of side effects such as nausea, headaches and dizziness.⁸ They can also cause bleeding so it is important to seek medical attention if there is any excess bleeding, blood in the urine, or blood when passing stool. Health professionals can adjust the dose of anticoagulant as necessary to make sure it is at a safe level.

Shared decision making

Although anticoagulation is beneficial for reducing the risk of stroke, anticoagulation can increase the risk of bleeding which can have its own adverse effects.⁷ Therefore, anticoagulants are not recommended for everyone. You and your health professional must come to a shared decision on whether anticoagulation is the best option for you. 

Score systems can be used to help clinicians work out the risk of a stroke in comparison to the risk of bleeding; these include: 

CHA2DS2‑VASc score 

This predicts your risk of stroke based on risk factors such as your age, sex, blood pressure, diabetes and history of clotting.⁹

ORBIT score

This predicts your risk of bleeding and is based on risk factors such as age, sex, bleeding history and kidney function.⁹

Your risks of stroke and bleeding can change with time, so anticoagulation will need to be reviewed regularly.⁴ 

How can I reduce my risk of atrial fibrillation and stroke?

There are many ways you can reduce your risk and improve your overall health. Stay proactive and involved in your health; there are several ways you can do this:

Making lifestyle changes

This can include reducing alcohol intake, maintaining a moderate amount of exercise and eating healthily.

Staying on top of other health conditions

This is important as health conditions such as diabetes and hypertension can increase your risk factors for other health conditions. This may involve taking medication to keep blood pressure or cholesterol levels under control.

Adhering to your medication and attending follow-up appointments 

Your risk of bleeding and stroke can change over time so it is important to attend regular follow-ups. You will be given an anticoagulant alert card, containing details of your anticoagulation, which is useful for any emergencies.⁸

Make sure you understand your condition and risk factors

You should have all the information from health professionals on the benefits and risks of treatment before making an educated and informed decision. If there is anything you are anxious or unsure about, make sure you clarify it with your health professional.  

Monitoring for signs of bleeding 

If you notice any bleeding while taking anticoagulation it is important to seek urgent medical advice. Bleeding may be in the form of nosebleeds, a cut that does not stop bleeding or blood in the stool or urine.

Summary

Anticoagulation is an essential part of the treatment of atrial fibrillation for many people. Anticoagulants such as rivaroxaban and warfarin help to reduce the risk of clots and therefore strokes. Anticoagulants can however increase your risk of bleeding, especially if you have other risk factors such as chronic kidney disease. Therefore, it is important that the decision for anticoagulation is a shared decision between you and your health professional.