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Usually the heart beats in a regular manner – the upper chambers (called atria) squeeze blood into the lower chambers (called ventricles) before being pumped around the body. Atrial fibrillation (also known as AFib or AF) is a kind of arrythmia. In atrial fibrillation, the heart quivers (or “fibrillates” in medical terms). This prevents the heart from effectively pumping blood around your body and can cause it to pool and form blood clots. If a blood clot breaks off and becomes an embolism (blood clots moving through your blood stream), it can become lodged in an artery and cause a stroke.

Atrial fibrillation affects up to 2% of the population and is the most common kind of arrythmia(1)
The risk of atrial fibrillation increases with age, affecting up to 5% of people over 65(1)

Some people experience atrial fibrillation as a one-off episode, others experience it occasionally (known as paroxysmal atrial fibrillation), and others experience it persistently (known as chronic atrial fibrillation).



Normally the heart beats regularly thanks to an electrical system or “pacemaker” that signals the chambers of the heart to contract (squeeze) and relax in a steady rhythm. With atrial fibrillation, there is a problem with the “pacemaker” which causes the top chambers (atria) of the heart to “quiver” rather than contract effectively. This affects the rest of the heart causing the bottom chambers (ventricles) to beat irregularly. An irregular heartbeat can seriously affect how well blood is pumped throughout the body and increases the chance of blood pooling and forming clots within the heart.



The most common causes of atrial fibrillation are listed below:

  • Long-term high blood pressure
  • Coronary heart disease
  • Valvular heart disease
  • Hyperthyroidism (an overactive thyroid gland)
  • Excessive alcohol or caffeine intake
  • Certain types of medicine and diseases (such as pneumonia) may trigger atrial fibrillation



Some of the risk factors for atrial fibrillation are listed below:

  • Congestive heart failure
  • High blood pressure and heart disease
  • Obstructive sleep apnoea
  • Age 65 or older
  • Diabetes
  • Prior stroke or thromboembolism
  • Vascular disease (abnormalities in the veins)
  • Females higher risk
  • Hyperthyroidism (treatable) (an over-productive thyroid)
  • Excessive caffeine or alcohol intake
  • Obesity
  • Physical inactivity

If you are concerned about atrial fibrillation, speak to your doctor about your risks and options.



If you suffer from one or more of these symptoms you should seek medical advice.

Some people with atrial fibrillation experience no symptoms – however, it is still important to treat the condition as it can lead to other complications such as stroke.



The diagnosis of atrial fibrillation can take multiple tests. Most commonly, your doctor will look at:

  • Physical examination
  • Medical history – does your family have a history of atrial fibrillation or blood clotting
  • Holter monitor – portable device to monitor your heartbeat
  • Electrocardiogram - a device used to monitor your heartbeat
  • Echocardiogram - an ultrasound device used to see how your heart muscles and valves are working
  • Blood tests
Atrial fibrillation doubles the risk of heart-related deaths and comes with a 5-fold increased risk of stroke(2)



A stroke occurs when there is a sudden blockage in the blood supply to the brain. Arteries are blood vessels which carry blood to the brain and supply it with oxygen, whereas veins are blood vessels which lead away from the brain.

There are two main kinds of stroke:

  1. Ischaemic stroke – This occurs when there is a sudden blockage of arteries, limiting the blood supply to the brain.
  2. Haemorrhagic stroke – This occurs when a blood vessel leading to the brain bursts.
Ichaemic stroke is the most common kind of stroke – accounting for up to 80% of all strokes(2)

Strokes can be extremely dangerous. When the blood flow to the brain is reduced, brain cells do not receive enough oxygen to survive and begin to die. Brain cells do not grow back, and therefore strokes can lead to permanent disability or death.



The symptoms of a stroke can vary depending on what area of the brain is affected. The Stroke Foundation recommends using the FAST test as an easy way to remember the common signs of a stroke:

Face: Check their face – is their mouth drooping?

Arms: Can they lift their arms?

Speech: Is their speech slurred? Can they understand you?

Time: Time is critical – if you see any of the above signs call 000 immediately.

Other symptoms of a stroke can include:

  • Weakness, numbness, or paralysis of the face, arm, or legs (on both sides)
  • Difficulty speaking or understanding speech
  • Dizziness, loss of balance, unexplained falls
  • Vision loss, blurring, or decreased vision in one or both eyes
  • Headache – usually severe and abrupt
  • Difficulty swallowing



Patients with atrial fibrillation are often treated with “blood thinners” or anticoagulants to reduce their risk of forming a blood clot in their heart or arteries. These treatments, because they are to prevent blood clots from forming, come with an increased risk of bleeding. Because of this, the prescription of certain treatments to patients comes with the need to weigh up the risk of stroke against the risk of bleeding and determine the most suitable path for that case. With patients that have an increased chance of stroke, the use of anticoagulant medication to prevent the stroke is likely to outweigh the risks of bleeding.



Anticoagulation medication (blood thinners) are drugs that reduce the ability of blood clots to form. These are often called “direct oral anticoagulants” or DOACs. These drugs do not break down clots that have already formed, but instead they prevent these clots from getting bigger or new clots from forming. Common anticoagulants include:

Anticoagulant medication quickly leaves the body, so skipping any medication poses an unnecessary risk to your health. It is extremely important to take this medication consistently and according to your healthcare provider's instructions.

No-one is exactly the same and you may require a different medication compared to others so it is important to speak to your healthcare professional about your specific anticoagulation medication. It is also important to note that aspirin (an antiplatelet agent) is not recommended, and studies have shown that it is ineffective for stroke prevention in atrial fibrillation compared to anticoagulants. Taking aspirin in addition to an anticoagulant over a long period also increases your bleeding risk. For some people this is necessary for their underlying medical problem but for many people there is no benefit.

Because aspirin is a non-prescription drug, your doctor may not realise you are taking it in addition to an anticoagulant. If you are taking aspirin in addition to an anticoagulant long-term check with your doctor how long it is recommended that the treatment be continued.



The most common side effect of using an anticoagulant is bleeding and bruising. Following is a list of side effects that you may experience when taking this medication. If you experience any of the following, you should contact your GP or healthcare professional immediately.

  • Long nose bleeds (longer than 10 minutes)
  • Cuts that won’t stop bleeding
  • Blood in vomit or spit
  • Bleeding gums
  • Blood in urine
  • Headaches
  • Nausea, diarrhea, heartburn

Women will commonly experience heavier bleeding during their period – if you are concerned about increased bleeding during your period you should speak to your doctor or healthcare professional.

If you suffer major head trauma or are unable to stop bleeding, you should seek immediate medical help.


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  1. Brieger, D., et al. National Heart Foundation of Australia and the Cardiac Society of Australia and New Zealand: Australian Clinical Guidelines for the Diagnosis and Management of Atrial Fibrillation 2018. Heart, Lung and Circulation 27(10): 1209 - 1266

  2. Senoo, K., Lane, D., & Lip, G. Y. (2014). Stroke and bleeding risk in atrial fibrillation. Korean circulation journal, 44(5), 281–290.
  3. Xu, J., Luc, J. G., & Phan, K. . Atrial fibrillation: review of current treatment strategies. Journal of thoracic disease 2016, 8(9): E886–E900.