Atrial fibrillation – causes and treatment

What is atrial fibrillation?

Atrial fibrillation is a common heart rhythm disorder in which the heart beats irregularly. To understand what a heart rhythm disorder is, it is important to know that the heart has a pacemaker – the sinus node. This produces regular electrical impulses at a frequency that depends on the level of physical exertion. This causes the heart muscle to contract. However, the heart’s atria and ventricles do not beat at exactly the same time, but rather in a staggered manner: first, blood is forced from the atria into the ventricles, and then pumped from the ventricles into the systemic circulation. In atrial fibrillation, the generation of electrical impulses at the sinus node is disrupted and other areas of the heart take over the electrical activity. This causes the atria to twitch in many small, rapid movements – known as atrial fibrillation. It also means that the atria no longer contract sufficiently: So, although the heart beats quickly, it does not beat strongly enough. Consequently, blood flow through the body is reduced. In the long term, this increases the risk of blood clots forming in the atria or in the brain, and can also lead to heart failure (cardiac insufficiency).

Typical symptoms of atrial fibrillation include palpitations, shortness of breath, dizziness and chest tightness. However, not all those affected realise they have a heart rhythm disorder, as atrial fibrillation often presents without symptoms or discomfort in its early stages. The condition can be diagnosed using an electrocardiogram (ECG), including a resting ECG, a long-term ECG and a stress ECG.

Why do people develop atrial fibrillation?

The causes of atrial fibrillation cannot always be clearly identified, but it is known that advanced age, high blood pressure and various heart conditions (particularly coronary heart disease – CHD) are the most common risk factors. Other risk factors include:

• sleep apnoea
• Diabetes mellitus
• Hyperthyroidism
• Heavy alcohol consumption
• Obesity
• Heart valve defects
• Heart failure
• Coronary heart disease (CHD)
• Other heart conditions

How can you recognise atrial fibrillation?

Atrial fibrillation is a condition that very often presents with no symptoms in its early stages. In fact, atrial fibrillation occurs without any symptoms in half of those affected, particularly among older people. The danger lies in the fact that this heart rhythm disorder is not harmless, as it promotes the formation of blood clots and can therefore also trigger a stroke. 

Typical symptoms include a racing or fluttering heart. This refers to a rapid, irregular or erratic heartbeat, which can be very unpleasant and also cause you to feel restless, weak or unwell. In the case of paroxysmal atrial fibrillation, these symptoms subside after a few hours or days. However, you should have the symptoms investigated, as untreated paroxysmal atrial fibrillation can develop into permanent atrial fibrillation (persistent or permanent atrial fibrillation). It is advisable to check your pulse regularly, especially if you suffer from high blood pressure (hypertension). In atrial fibrillation, the pulse is rapid and irregular, and the heart often beats at over 100 beats per minute at rest.

Other possible accompanying symptoms of atrial fibrillation include:

• Restlessness and anxiety
• Shortness of breath
• Feeling of weakness
• Episodes of dizziness
• Chest pain
• Brief loss of consciousness

Which doctor should you see for atrial fibrillation?

It is not uncommon for atrial fibrillation to be discovered by chance. Whilst a racing or irregular heartbeat may be the first signs of this heart rhythm disorder, a cardiologist is best placed to make a definitive diagnosis using an electrocardiogram (ECG). Beforehand, the doctor will ask about any pre-existing conditions and symptoms, and will measure your blood pressure and pulse. On a resting ECG, atrial fibrillation is indicated by typical deviations from the normal sinus rhythm. A stress ECG and a 24-hour ECG may be useful. The latter is particularly recommended if paroxysmal atrial fibrillation is suspected, as the ECG may show a normal rhythm at the time of recording.

Other investigations that may be carried out include a blood test and echocardiography (heart ultrasound).

How is atrial fibrillation treated?

The primary aim of treatment is to relieve symptoms. Another aim is to improve exercise tolerance, which is limited in this condition. To achieve this, many patients – particularly those suffering from high blood pressure or heart disease – must first have their underlying condition treated. Furthermore, various specific medicines are available for treating atrial fibrillation, although these cannot always stop the condition. These are primarily beta-blockers and calcium channel blockers, which slow down the rapid heart rate, relieve the strain on the heart and alleviate symptoms. It is also important to note that medicines designed to stop atrial fibrillation can, unfortunately, trigger other dangerous cardiac arrhythmias. It is therefore recommended that a doctor reviews the use of these medicines every three months. It is also advised to monitor the levels of the electrolytes potassium and magnesium in the blood and to keep an eye on kidney and thyroid function.

It is not always possible to restore a normal heart rhythm using medication. In such cases, electrical cardioversion is an option. This involves restoring the normal sinus rhythm. The patient is given an electric shock using a defibrillator, which is intended to stop the atrial fibrillation. Cardioversion is almost always successful; however, atrial fibrillation often recurs. This is one reason why, following cardioversion, it is usually recommended that patients take medication to prevent relapses. Another option for treating atrial fibrillation is a procedure known as catheter ablation, which is successful in the long term in many cases. In catheter ablation, heart cells are destroyed using high-frequency current or cold to stop atrial fibrillation. To do this, a catheter is inserted into the heart – usually via the femoral vein – and the heart cells that trigger atrial fibrillation are specifically destroyed. 

Preventing stroke

Preventing stroke is also very important, as atrial fibrillation carries a risk of blood clots forming because the heart’s atria no longer contract in a coordinated manner, causing the blood to flow more slowly there. For this reason, patients are advised to take anticoagulant medication, particularly if other risk factors are present. 

The so-called CHA2DS2-VASc score is used to determine stroke risk more accurately. This score uses points – for risk factors such as heart failure, high blood pressure, age or gender – to create a more precise risk profile. For patients suffering from atrial fibrillation who score at least two points on the CHA2DS2-VASc score, oral anticoagulation with direct oral anticoagulants (DOACs) is recommended. To assess the risk of bleeding associated with oral anticoagulation, another score has also been developed – the so-called HAS-BLED score. Like the CHA2DS2-VASc score, it is based on a points system and takes into account factors such as age, high blood pressure or a history of stroke.

What is the progression of atrial fibrillation?

If left untreated, atrial fibrillation continues to progress. Initially, it occurs only in episodes, then lasts for longer periods and eventually becomes permanent. With appropriate treatment, however, the condition can usually be managed effectively. Nevertheless, patients with atrial fibrillation often notice that their heart is no longer beating as it should, and this causes anxiety for many – for example, about whether they can still exercise and continue with their normal activities. Recent research findings suggest, however, that moderate exercise improves fitness and leads to a better quality of life.

What complications are associated with atrial fibrillation?

Although the condition is not immediately life-threatening, it can have a number of undesirable consequences in the long term. One possible complication is heart failure, as the heart has to work harder overall when suffering from atrial fibrillation in order to supply the body with sufficient blood, oxygen and nutrients. Furthermore, atrial fibrillation can worsen pre-existing heart failure. However, as already mentioned, one of the greatest risks is the potential formation of blood clots, which can arise not only as a result of anticoagulation but also due to the irregular heart rhythm.