Atrial fibrillation (sometimes referred to as AF or A-fib) is the most common heart rhythm disturbance – or cardiac arrhythmia - in the UK, affecting around one million adults.
In AF, the normal regular electrical impulses of the heart become disorganised, leading to an irregular heartbeat. When the heart beats normally, its muscular walls tighten and squeeze (contract) to force blood out and around the body – they then relax so the heart can fill with blood again. This process is repeated every time the heart beats - an average of 108,000 times a day!
AF happens when abnormal electrical impulses suddenly start firing in the atria so that the heart’s upper chambers contract randomly, and sometimes so quickly that the heart muscle cannot relax properly between contractions. These abnormal impulses override the heart’s natural pacemaker, which can no longer control the rhythm of the heart. This causes an irregular pulse. There are many causes of AF, notably coronary artery disease (which starves the heart muscle of oxygen and predisposes to abnormal electrical activity), abnormal enlargement of the heart (as caused by valvular diseases for example), and excessive alcohol consumption. In some cases, the underlying reason for the AF may remain obscure.
There are four types of AF, categorised according to how long the episodes last:
- Paroxysmal atrial fibrillation: episodes come and go, usually stopping within 48 hours without any treatment.
- Persistent atrial fibrillation: episodes last for longer than seven days although treatment can lessen the duration.
- Long-standing persistent atrial fibrillation: continuous atrial fibrillation for one year or longer.
- Permanent atrial fibrillation: atrial fibrillation is present all the time.
Who is at risk of AF?
While anyone of any age can develop AF, some people are at higher risk if they fall into any of the following categories:
- Those aged over 65 as it is more common in older people, affecting about 7% of over 65s and about 17% of over 85s.
- Rates are higher among men although women also develop AF. People who have high blood pressure, a heart valve problem (such as a narrowing of the valve), or coronary artery disease (where arteries to the heart become clogged with fatty substances which can cause blood clots and other problems).
- Individuals with underlying conditions such as thyroid disease, chronic lung disease, obstructive sleep apnoea syndrome, or those who have a serious acute infection or illness.
- People who use tobacco or stimulants, or those who drink to excess.
What are the symptoms of AF?
People with AF may experience some or all of the following:
- Heart palpitations or a feeling that the heart is fluttering
- Dizziness, light headedness and sometimes fainting
- Feeling weak and/or fatigued
- Feeling short of breath
- Reduced ability to exercise, even lightly
- Chest pain or a feeling of heaviness in the chest area.
How is AF diagnosed?
For most people AF is unpleasant but not life threatening. However, it can cause serious complications, such as stroke, so it’s important to see your GP as quickly as possible if you are experiencing any of the above symptoms. Your GP will measure your pulse and if she or he is concerned, they may order a painless test called an electrocardiogram (ECG) that will determine if the electrical activity of the heart is abnormal.
How can I measure my heart rate?
An unusually high or low heart rate may indicate an underlying problem, so see your GP if your resting heart rate (when you’re lying down and relaxed) is consistently above 100 beats a minute, or if you’re not a trained athlete and your resting heart rate is below 60 beats a minute.
To measure your heart rate, you need to check your pulse. You can do this by placing two fingers on your wrist between the bone and the tendon over your radial artery, located on the thumb side of your wrist.
As soon as you feel your pulse, count the number of beats in 15 seconds. Multiply this number by four to calculate your beats per minute.
There can be other causes for experiencing the above symptoms so it’s important to get AF ruled out –because it can cause serious problems if it’s left untreated.
How is AF treated?
Some people with AF are prescribed medication to either slow the heart rate to a normal range or restore a normal heart rhythm. Other people might require surgery or other type of intervention to prevent recurrence. Furthermore, and depending on the risk of stroke and/or blood clots, others may also need blood thinners such as warfarin or apixaban. Your GP will advise on the best course of action, and may refer you to a specialist clinic at your local hospital for further tests.
In some cases, AF can be entirely cured. This tends to be amongst patients whose hearts are structurally normal and whose AF has been relatively recent, or who are appropriate for ‘ablation therapy’ (which can identify the cluster of cells in the atria that are generating the abnormal electrical impulses and can destroy them).