Atrial fibrillation

Atrial fibrillation (AF) is a condition that affects the heart, causing an irregular heart beat. This is known as a heart rhythm disorder (arrhythmia).

Key points:

  1. If you notice your pulse seems irregular, see your doctor.
  2. Atrial fibrillation is common as we get older, so see your doctor for blood pressure and pulse checks.
  3. Learn about the signs and symptoms of atrial fibrillation so you can seek help early.
  4. Keep your heart healthy by eating healthy foods, keeping physically active and being smoke free.
  5. If you do have atrial fibrillation, take your medication carefully as this can reduce symptoms and prevent complications such as stroke.

What causes AF?

Normally, your heart beats at a rate of 60 to 100 beats per minute when you are at rest, and all of the heart chambers beat in unison. If you have AF, the electrical signals that control your heartbeat are abnormal. These signals cause the upper chambers of your heart (the atria) to beat unevenly and very quickly. In fact, the atria beat so quickly that the lower heart chambers (the ventricles) can’t quite keep up, and your heart doesn’t beat in the usual, coordinated manner.

This results in an irregular and rapid heart rate, often ranging from 100 to 180 beats per minute. When this happens, the heart cannot pump blood around the body as well as it needs to.

(Khan Academy, 2014)

Atrial fibrillation can be:

  • Acute – a one-off episode of AF that may be the result of a particular short-term problem such as alcohol intoxication.
  • Paroxysmal – repeated bouts that usually last less than 48 hours
  • Chronic – ongoing uneven and fast heartbeat.

Who is at risk of AF?

Atrial fibrillation is a common problem affecting approximately 35,000 people in NZ (1% of the population). The risk of developing AF increases with age, occurring in about 5% of people older than 65 years and about 10% of people older than 80 years. Many people do not know they have it, with approximately one-third of those with AF thought to be undiagnosed.

Other things that increase your risk of AF include:

  • heart disease or heart valve problems
  • long-standing high blood pressure
  • chronic lung disease
  • an overactive thyroid gland.

It is possible for otherwise healthy people to have AF – in fact up to one-third of people with AF have no obvious underlying cause; a condition known as lone atrial fibrillation.

Atrial fibrillation is often picked up when having a medical examination for something else.

What are the risks associated with AF?

Atrial fibrillation (AF) affects at least 5 in every 100 (5%) of people in New Zealand aged over 65 years. Having AF puts you at higher risk of some conditions compared to people without AF. For example,

  • you are 4 to 5 times more likely to have a stroke
  • you are 3 times more likely to have heart failure
  • you are twice as likely to have myocardial infarction and dementia.
Therefore to reduce these risks it is important to treat your AF.

How does AF cause stroke?

Because the atria are contracting quickly and abnormally, they don’t pump blood through the heart properly. Blood can then pool in the heart and a blood clot may form. If the clot breaks loose and leaves the heart, it can travel via your blood vessels to other organs in your body. If a clot lodges in a blood vessel that supplies your brain and cuts off the blood supply, it causes a stroke.

What are the symptoms of AF?

If you have AF, you may experience palpitations (an awareness of your heart beating or pounding in your chest). Other symptoms include:

  • chest pain
  • dizziness
  • light-headedness
  • shortness of breath
  • fatigue and tiredness.

Some people have no symptoms at all, and AF is only detected after a doctor (or another healthcare worker) notices that your pulse is irregular.

Is an irregular pulse always due to AF?

Occasional missed beats or extra beats between regular beats are very common and usually nothing to worry about, but best discussed with your doctor. AF on the other hand has no pattern to it at all and is continuously irregular.

Take a test

Quick guide from the British Heart Foundation:

  1. Put one of your hands out so you’re looking at your palm.
  2. Use the index/first finger and middle finger of your other hand and place the pads of these fingers on the inside of your wrist. You should place them at the base of your thumb near where the strap of a watch would sit.
  3. Press lightly and feel the pulse. If you can’t feel anything press slightly harder or move your fingers around until you feel your pulse.
  4. Once you’ve found your pulse, continue to feel it for about 20-30 seconds. Feel the rhythm of the pulse and check if it’s regular or irregular.

Listen to these examples from the British Heart Foundation

How is AF diagnosed?

AF is diagnosed using a simple, painless test called an electrocardiogram (ECG).

  • When you have an ECG, small patches connected to wires (electrodes) are placed on your chest to measure the electrical impulses given off by your heart.
  • These electrical impulses are recorded on a piece of paper called an ECG strip.
  • The abnormal pattern of electrical impulses seen in people with AF is easily detected by the ECG.

However, if you have paroxysmal (irregular bouts of) AF, your heartbeat may be normal at the time the ECG is recorded. To detect paroxysmal AF, you may need to have a Holter monitor test arranged.

  • A Holter monitor is a portable device that you wear under your clothes.
  • It continuously records your heart's electrical impulses for at least 24 hours.

What are the treatment options for AF?

The treatment for atrial fibrillation varies from person to person depending on a number of factors, including the severity of your symptoms, the cause and duration of your atrial fibrillation, and whether you have any underlying health problems. However, in general, the main aims of treatment are to:

  • prevent blood clots, therefore lowering risk of stroke
  • control your heart rate to restore a normal heart rhythm.

Medication

Blood clot prevention

Having AF puts you at high risk of having a stroke, and preventing blood clots is one of the most important parts of treating AF, as blood clots can cause strokes. To prevent blood clots, you may be prescribed blood-thinning medicines (anticoagulants) such as warfarin or dabigatran. Because anticoagulants stop blood clots, they may cause bleeding. Your doctor will consider your risk of bleeding and whether anticoagulants are suitable for you. Read more about anticoagulants and which anticoagulant is best for you. Aspirin is no longer recommended for preventing blood clots in people with atrial fibrillation.

Rate control

You may be prescribed medicines to slow down the rate at which your ventricles are beating and help bring the heart rate to a normal level. Medicines used to control the heart rate include groups of medicines called beta blockers (for example, metoprolol, bisoprolol and carvedilol), or calcium channel blockers (diltiazem and verapamil). If your heart rate is still not settled with beta blockers and calcium channel blockers, your doctor may also add digoxin

Rhythm control

If you are not doing so well on rate control medications your doctor may prescribe medicines or recommend procedures to control your heart's rhythm. Medicines used to control the heart rhythm include amiodarone, sotalol, flecainide, propafenone and disopyramide. These are usually prescribed by a cardiologist.  

Other treatment options

  • Electrical cardioversion is sometimes recommended to treat fast or irregular heartbeat. It involves the use of low-energy electrical shocks to trigger your heart into a normal rhythm. It is performed under a general anaesthetic.
  • Catheter ablation is a more invasive method that may be used to restore a normal heart rhythm. In this procedure, a catheter (a long, thin tube) is inserted a vein in the leg or arm and threaded all the way to the heart. Radio wave energy is used to damage the small portion of tissue responsible for the abnormal electrical signals.
  • Pacemakers help maintain a normal heart rhythm. They are used for people with AF that has not been effectively treated with less invasive treatments. Before inserting a pacemaker, catheter ablation is used to destroy the atrioventricular (AV) node in the heart. The AV node is a part of the electrical control system of the heart that coordinates the atrial and ventricular chambers. The pacemaker takes over the AV nodes role of maintaining a normal heart rhythm.
  • Heart surgery is very rarely required. The most common operation performed is known as the maze procedure, where a number of small incisions are made in the atria (upper chambers) of the heart to create a pattern of scar tissue. The scar tissue (which does not carry electrical currents) prevents the abnormal electrical signals that cause atrial fibrillation from travelling through the heart and causing an abnormal heartbeat.

Learn more

Tests & Investigations for Heart Disease Heart Foundation (NZ)
Learn about heart disease: atrial fibrillation Cardio smart (USA)
Arrhythmias – Normal heart beat animation Watch, Learn, Live: Interactive Cardiovascular Library – American Heart Association
Atrial fibrillation – Conduction system of the heart Watch, Learn, Live: Interactive Cardiovascular Library – American Heart Association

References

  1. An update on managing patients with atrial fibrillation BPAC 2017
  2. Atrial fibrillation  National Heart, Blood and Lung Institute, NHI, US.
Credits: Editorial team. Last reviewed: 07 Sep 2017