Atrial fibrillation: the causes, treatments and risks explained

Atrial fibrillation is the most common heart rhythm problem affecting around 1.5 million people in the UK alone. In fact, in the over 40s, there is a one in four lifetime risk of developing this condition. Although some people may not notice any symptoms, for others, atrial fibrillation can be debilitating and disrupt their everyday lives.

To understand atrial fibrillation, it helps to first get an idea of how your heart usually works.

What makes your heart beat?

Your heart is a pump largely made of muscle and has its own electrical system, which controls how and when the muscle contracts. These contractions cause your heart to beat. 

There are four chambers in your heart: the left atrium, right atrium, left ventricle and right ventricle. Blood that has already passed around your body (deoxygenated blood) flows into the right half of your heart and then to your lungs to pick up more oxygen, while blood from your lungs (oxygenated blood) flows into the left side of your heart and is pumped out to the rest of your body.

Your heart’s electrical system controls the contractions of these chambers and these electrical signals start in a special bundle of cells in your right atrium (your natural pacemaker). These electrical signals then spread across your heart muscle, allowing it to contract in a coordinated fashion. 

Any problems with the electrical activity of your heart can therefore affect how your heart beats and how often (your heart rate). During atrial fibrillation, a problem with your heart’s electrical activity causes irregular heart beats and often also leads to an increase in your heart rate. 

What are the symptoms of atrial fibrillation?

Some people with atrial fibrillation have no symptoms but many experience palpitations, breathlessness on physical activity, a reduced ability to complete physical activities, dizziness and chest discomfort. You may not experience all of these symptoms as symptoms vary between individuals. 

Are you at risk of atrial fibrillation?

Your risk of atrial fibrillation increases as you get older, with most cases diagnosed in the over 60s. It is also more common in men and in those with a family history of the condition. Other risk factors for atrial fibrillation include high blood pressure, being overweight, abnormalities of the heart valves, an overactive thyroid and obstructive sleep apnoea. Although age and genetics are not risk factors you can change, assessment and treatment of other risk factors can significantly help reduce the chances of you developing atrial fibrillation.

One of the biggest risk factors that you can control is high blood pressure. Reducing high blood pressure through lifestyle changes and medication will reduce your risk of developing atrial fibrillation. 

In the last few years, being overweight or obese has also been identified as a key risk factor. If your body mass index (BMI) is over 25, losing excess weight and maintaining a healthy weight will help protect you against developing atrial fibrillation. 

Regular exercise can help reduce your blood pressure and lose excess weight. However, too much high intensity exercise can put excess strain on your heart and increase your risk of atrial fibrillation. 

Alcohol and smoking both increase your risk of atrial fibrillation. As smoking is linked to a range of other serious health conditions, it is recommended that you try to quit — your GP can provide you with information on local stop smoking services. As for alcohol, you do not need to stop drinking altogether but instead drink in moderation. It is recommended that both men and women do not drink any more than 14 units of alcohol every week. 

Getting a diagnosis of atrial fibrillation

If you’re concerned that you have atrial fibrillation, see your GP. They will ask about your symptoms and your medical history. They may also check your pulse as episodes of atrial fibrillation cause your pulse to be irregular. 

If your episodes of atrial fibrillation are fleeting, you may need further tests to get a diagnosis and rule out other causes of your symptoms. This may include blood tests, an electrocardiogram (ECG), an echocardiogram or wearing a heart monitor for anywhere between 24 hours to two weeks.

Types of atrial fibrillation

Atrial fibrillation is a progressive condition, which means it may start off with fleeting, infrequent episodes but over time, those episodes may occur more often and last longer. 

Atrial fibrillation can therefore be split into four different types: 

• Paroxysmal — this comes and goes on its own, with episodes lasting less than seven days and may require treatment to reduce frequency
• Persistent — when episodes last for more than seven days and/or your irregular heart rhythm doesn’t return to normal on its own but needs treatment
• Long-standing persistent — when episodes last for over a year
• Permanent — long-standing atrial fibrillation where you and your doctor have agreed that the irregular heart rhythm can’t be reversed and instead the focus is on keeping your heart rate within a healthy range and reducing your risk of complications

As atrial fibrillation is a progressive condition and may cause complications, it is important to see your GP if you develop symptoms that are affecting your quality of life or if you’re concerned about the possibility of atrial fibrillation.

Complications of atrial fibrillation

The main complication of atrial fibrillation is an increased risk of stroke — if you have atrial fibrillation you are five times more likely to have a stroke than someone of an equivalent age in the general population. 

The irregular heart rhythm caused by atrial fibrillation prevents your heart from pumping blood as efficiently as it should. This allows blood to pool in your heart, which increases the likelihood of clots forming. A stroke occurs when one of these clots travels to your brain. 

If you have been diagnosed with atrial fibrillation, you will need to be assessed for your stroke risk. There are other factors that also contribute to your risk of stroke eg age, high blood pressure, history of previous heart attack or stroke and diabetes. Based on your stroke risk assessment, you may be prescribed anticoagulant medication ie blood thinners to reduce your risk. 

Atrial fibrillation can also increase your risk of developing heart failure. This is because a persistently irregular heartbeat and rapid heart rate places greater strain on your heart. Symptoms of heart failure include breathlessness and fluid collecting around your ankles.

Treatment to restore a normal heart rhythm and to slow your heart rate down will give your heart a chance to recover and reduce your risk of heart failure. 

Is atrial fibrillation life-threatening?

It is easy to feel panicked during an episode of atrial fibrillation, however, it is important to remember that atrial fibrillation in itself is not life-threatening. If you feel well during an episode of atrial fibrillation, then it may not be necessary to seek medical attention immediately, particularly if the diagnosis has already been made and if the risk of stroke has already been addressed. However, if you do feel ill during an episode, seek medical attention as soon as possible.

How is atrial fibrillation treated?

If you are diagnosed with atrial fibrillation, it is important to maintain a healthy weight, exercise regularly and reduce your blood pressure. Being overweight and inactive and having high blood pressure can all worsen your condition.

Aside from lifestyle changes, your doctor will also recommend treatments that directly target your symptoms. There are broadly two approaches: the rate control strategy and the rhythm control strategy. 

The rate control strategy accepts that your heart rhythm can’t be restored and instead focuses on slowing down your rapid heart rate by taking medications, such as beta-blockers. 

The rhythm control strategy focuses on restoring a normal heart rhythm by taking medications. There are a limited number of rhythm control medications available; the milder medications tend to have fewer side effects whereas the more potent medications tend to have greater side effects. Finding the right treatment for you is important so you may need to try more than one medication. 

Regardless of the treatment strategy planned, your doctor will assess your risk of stroke and recommend whether blood thinning medication is appropriate for you to reduce your risk of stroke.

Hospital treatment for atrial fibrillation 

There are two main treatments for atrial fibrillation, which are performed in a hospital: cardioversion and catheter ablation.

Cardioversion 

Cardioversion is performed under a general anaesthetic, so you’re asleep. While you are under general anaesthesia, a controlled shock will be applied to your heart to force it back into a normal rhythm. This treatment is only suitable if you are already taking blood thinners. 

Although the procedure is effective in most cases, there is no guarantee for when your atrial fibrillation will return — it could be a matter of minutes, days, weeks or months. After your procedure, you may be prescribed medications to reduce the risk of your atrial fibrillation returning.

Catheter ablation

Catheter ablation can be performed under local or general anaesthetic. It involves passing thin tubes (catheters) into a vein in your groin. The catheter is guided through your veins and passed into your heart, specifically the right atrium. A small hole is made into your left atrium so the catheter can pass through and then directed towards the four veins that connect to your left atrium — cells in these veins are often responsible for the irregular electrical activity that causes atrial fibrillation. Heat energy or freezing is then used to destroy these cells. 

This procedure is more successful in the earlier stages of atrial fibrillation; it has a success rate of 70–80% if you have paroxysmal atrial fibrillation and about 60% if you have persistent atrial fibrillation. You may need more than one catheter ablation procedure. After your procedure you may still need medication to reduce the risk of your atrial fibrillation returning.

Treatment to reduce your stroke risk

In most cases of atrial fibrillation, you will need to continue taking blood thinners to reduce your risk of stroke. In the past, warfarin was the only option; taking warfarin requires regular blood tests to check the ‘thinness’ of your blood which can be affected by diet and other medications. However, there are now other medications that are just as effective, have a lower risk of bleeding and don’t require regular blood tests — these are called direct oral anticoagulants (DOACs) and include dabigatran, rivaroxaban, apixaban and edoxaban.

What’s the future of atrial fibrillation treatment?

Our understanding of atrial fibrillation increases every year, with treatments continuing to improve. In the last 10 years alone, catheter ablation has become safer and more targeted. However, in the near future, it may be replaced by a new treatment showing promising results in trials called pulse field ablation. This uses electrical energy instead of heat energy or freezing to destroy the heart cells where atrial fibrillation arises. This new procedure could make it even safer to destroy the cells responsible for atrial fibrillation.