Atrial fibrillation

Read personal stories from myheart members with atrial fibrillation.

Watch CRY Patron Tom James MBE talk with Professor Sharma about his experience of finding out and living with atrial fibrillation.

What is atrial fibrillation?

Atrial fibrillation (AF) is the most common heart rhythm disorder. It affects around 1-2% of the overall population. It is more common in men and is increasingly common as people age [1]. While it is associated with other medical conditions such as high blood pressure, obesity and other types of heart disease [2], people who are otherwise fit and healthy may still develop AF.

AF occurs when the electrical signals in the heart’s upper chambers, the atria, become chaotic and disordered, overriding the heart’s natural pacemaker. This causes the heart to beat irregularly. The heart rate is highly variable and can beat very fast and in turn very slowly. This irregularity affects the efficiency of the heart and can reduce the amount of blood it is able to pump around the body [3].

Early in the condition, AF will occur for a short period before the heart corrects itself and returns to a normal rhythm (this is known as paroxysmal AF [4]). Left untreated, these episodes last longer and it becomes more difficult to restore the heart’s normal rhythm before eventually the heart rhythm remains irregular (i.e. in AF) permanently [5].

What symptoms does AF cause?

The symptoms of AF vary between people, and many people are not aware of any symptoms at all. The most common symptom is palpitations. They may be associated with chest pain, light-headedness, breathlessness and fatigue [2]. They may start suddenly and last for a few minutes to several hours. Often there is no pattern to when the palpitations occur but there may be particular triggers for some people. These too are variable and include exercise, emotional stress and alcohol [4].

As AF becomes chronic and long-standing sudden palpitations become less common. When the symptoms are less obvious, people may complain from breathlessness, a lack of energy or fluid retention [2].

How is AF diagnosed?

AF causes an irregular pulse that can often easily be felt at the wrist. In asymptomatic individuals, this may be the only sign of the condition and finding an irregular pulse should always raise the suspicion of AF [4]. Formal diagnosis requires an ECG that shows the chaotic electrical activity and irregular heart rhythm. Several ECGs or a prolonged recording may be needed for people with paroxysmal AF since the ECG is frequently normal between episodes [4].

In addition, other tests may be required to look for associated conditions. These may include an echocardiogram to look at the structure and function of the heart or a prolonged ECG to monitor the variation in heart rates during the day and night.

What are the risks of AF?

Although the symptoms of an episode of AF can be very unpleasant, an acute episode is not life threatening and can often be managed at home with an appropriate support and treatment plan.

The most important potential risk of AF is having a stroke [6]. A person’s risk of suffering a stroke is 5 times higher if they have AF [4] because blood flowing through the heart’s upper chambers (the atria) can slow, allowing small blood clots to form, particularly in the left atrium. These blood clots have the potential to break off and travel through the bloodstream blocking blood vessels in other organs such as the brain, where they can lead to a stroke. The risk of an individual with AF having a stroke is not related to the number of episodes of AF they have, but to the presence of other conditions that can independently increase the risk of having a stroke. These include heart failure, high blood pressure, diabetes, arterial disease (such as coronary artery disease or peripheral vascular disease) having had a previous stroke, and increasing age [4]. Females are also at a slightly higher risk of stroke than males as they get older [7].

AF can also lead to memory problems and cognitive decline [8] and is a common cause of hospital admissions [7].

How is AF treated?

Like many things related to AF, the treatment options are varied and complex and should be tailored specifically to the individual. There are three broad focuses of treatment: prevention of stroke; maintaining the heart’s normal rhythm; and preventing the heart beating too fast when in AF.

Stroke prevention is the mainstay of treatment in AF. For the vast majority of patients this is done by means of thinning the blood with medications known as anticoagulants so that clots cannot form. Traditionally warfarin has been the only effective drug and is still used widely today. However, there are now several other anti-coagulant drugs that are useful in AF [8]. The decision over which one is right should be discussed between the patient and their doctor. Aspirin is not recommended for stroke prevention in people who have AF [4].

For those people who cannot take anticoagulant medications, a device can be implanted in the left atrium of the heart to prevent blood clots breaking off and entering the bloodstream [9].

Keeping the heart in its normal rhythm and preventing the recurrence of AF is another important goal of the treatment of AF. Medications called antiarrhythmics can be used to help achieve this. There are many available and each has particular benefits and considerations to take into account. Commonly prescribed antiarrhythmics in the UK include flecainide, sotalol, dronedarone and amiodarone [10].

Another option for the prevention of AF recurrence is an ablation procedure. Ablation of AF aims to prevent the disordered electrical signals seen in the atria during AF. Wires called catheters are introduced into the left atrium of the heart via the femoral vein at the top of the leg. Once in the left atrium, these catheters are used to cauterise specific areas of heart tissue to prevent the abnormal conduction of electrical signals. Ablation is an effective treatment for preventing AF in the short and medium term and although it does not offer a permanent cure it can reduce the need to take antiarrhythmic medication [11].

When an episode of AF occurs, normal rhythm can be restored with a procedure called a cardioversion [4]. This involves giving a controlled electrical shock to the heart while the patient is under conscious sedation or anaesthesia. The shock stuns the electrical tissue of the heart and allows the natural pacemaker to restore the normal heart rhythm. Intravenous medication can also be used instead of or in conjunction with the electric shock.

Since it is very difficult to get rid of AF permanently, an alternative treatment option is to prevent the heart beating very fast when AF occurs. This is because it is when the heart beats very fast that most symptoms occur. The most commonly used family of drugs for this are beta-blockers although others such as calcium channel blockers and digoxin may also be used [4][10]. For those individuals who have AF with slow heart rates, an electronic permanent pacemaker can be used to prevent the heart beating too slowly.

The treatment of any individual with AF will be spefically tailored to their particular situation, depending on their symptoms, type of AF, and other medical history but will involve a combination of the strategies discussed above .

AF in young people

While AF is more common in older people, it can affect young people in the absence of any other heart problems. In this situation there may be an underlying genetic cause such as a problem with a sodium channel in the heart. These sodium channels are important for determining the electrical properties of the heart and problems can lead to a number of heart rhythm problems including AF.

The treatment of AF in young people is similar to that described above. In general the risk of stroke in young people is lower so there is less need for anticoagulant medications [8]. In addition, ablation may be recommended more commonly as the initial treatment in young people with otherwise normal hearts as it has been shown to be as effective as antiarrhythmic medication in such patients [12].

AF in pregnancy

A first episode of AF during pregnancy is rare in women without previously known heart problems. Around 50% of pregnant women who have pre-existing AF have an episode during their pregnancy [3].

Many of the drugs commonly used for the treatment of AF have potential problems in pregnancy: beta-blocker drugs may cause reduced growth of the foetus. Alternatives such as verapamil and diltiazem are generally safe. Amiodarone can cause harm to the foetus and should only be used in emergencies. Electrical cardioversion has been used safely in pregnant women. Regarding anticoagulants, warfarin is known to harm the foetus and should be avoided. The newer anticoagulant medications are also not recommended. Daily injections of low-molecular weight heparin (LMWH) can be used in their place at much lower risk [4].

AF in athletes

AF has been shown to occur more frequently in men who participate in prolonged strenuous exercise such as endurance sports [13][14]. This is most likely due to the structural and functional changes seen in the heart in response to prolonged exercise.
Treatment options are often slightly different since beta-blocker drugs are not well-tolerated in athletes and other drugs may not be potent enough to treat the fast heart rates that can occur with exercise-induced AF. Therefore ablation therapy may be considered earlier. Individuals taking anticoagulant medications cannot participate in contact sports due to the risk of bleeding [4].

Watch CRY myheart cardiologist Dr Michael Papadakis talk about why people with ICD are not allowed to play contact sports.

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