Atrial Fibrillation
Atrial fibrillation (AF) is a common arrhythmia (heart rhythm problem) that affects around 1.7 million people in the UK, mostly older individuals.
This arrhythmia can cause symptoms including palpitations, shortness of breath, chest pain and dizziness. Sometimes people may have the condition but not feel unwell (asymptomatic atrial fibrillation). Asymptomatic AF is a challenge to diagnose, as it can be intermittent.
AF can lead to strokes by blocking blood flow to the brain, resulting in disabilities. Some individuals benefit from taking blood thinners to prevent strokes, but this depends on various factors like age, gender, and other health issues.
About half of people in the UK with AF are unaware of their condition. These people may be at high risk of stroke without realising it. Even more importantly, for some of these people, the stroke risk can be reduced but only if the diagnosis is made and treated.
What is AF? - When to see a cardiologist - Symptoms - Timing - AF at night - Causes - Treatments - Complications
What is Atrial Fibrillation?
AF is the most common heart rhythm disturbance in the UK. It is a chaotic rhythm in the upper chambers of the heart, which can come and go for short periods, or be present persistently. The normal heart beart is caused by an organised flow of electricity through the heart. When the organisation of the heart beats breaks down and becomes chaotic, this is called “fibrillation”. When fibrillation affects the upper chambers of the heart (the atria) it is called “atrial fibrillation”.
When to See a Cardiologist
A cardiologist can diagnose and treat arrhythmias and other heart conditions that cause similar symptoms. Cardiologists have access to a wide range of tests and up-to-date wearable technologies that may not be available to other doctors. A cardiologist with specific expertise in heart rhythm disorders is called an electrophysiologist and these sub-specialists may use diagnostic tests and wearable devices in a more targeted way than other cardiologists, offering - in some cases - quicker and more cost-efficient diagnosis.
Once atrial fibrillation is confirmed, a cardiologist can identify and treat underlying causes, reduce symptoms, and lower stroke risk.
Heart rhythm specialists (electrophysiologists) can also adjust drug treatment or use pacemakers or ablation treatments to alleviate symptoms, even in long-term atrial fibrillation cases.
Symptoms
AFib symptoms can vary a lot in severity, from being unnoticeable to being severe and interfering with everyday life.
Symptoms of AF include:
Irregular pulse
Palpitations
Breathlessness
Dizziness, lightheadedness and fainting
Chest discomfort
Fatigue, weakness and confusion
In general, chest symptoms (chest pain, palpitations, breathlessness) are more common in younger people with atrial fibrillation. As patients get older, or have more established atrial fibrillation, they are more likely to experience the less specific symptoms such as fatigue, lightheadedness, weakness and confusion.
Atrial fibrillation can be intermittent or persistent, and some people may not experience any symptoms. Wearable tech like Apple Watch and smartphone apps like FibriCheck can help detect atrial fibrillation even without symptoms.
Timing of AFib Symptoms
There are four different patterns of atrial fibrillation:
Paroxysmal - attacks last up to 48 hrs
Persistent - attacks last longer than a week
Long-standing persistent - the patient has been in atrial fibrillation for over a year
Permanent - both doctor and patient accept that atrial fibrillation will continue life-long
The different patterns of atrial fibrillation cause different patterns of symptoms. Clearly someone with paroxysmal AF will only feel unwell during an attack. In between attacks they will feel normal, though the thought that an attack may come on at any time can itself be unpleasant and difficult to live with.
Paroxysms (attacks) of atrial fibrillation may have different triggers. Avoiding the triggers may reduce or entirely prevent the symptoms. Common triggers for atrial fibrillation include:
Alcohol
Eating a large meal
Caffeine and other stimulants
Poor sleep
Stress, anxiety and emotional upset
AF at Night
Some patients with paroxysmal atrial fibrillation find that their attacks only ever start at night. Nocturnal AFib can be due to obstructive sleep apnoea or high vagal tone. (a low resting heart rate). Where sleep apnoea is the cause, treating the sleep apnoea can - in many cases - effectively treat the atrial fibrillation. Failing to diagnose and treat sleep apnoea can lead to worse AF and can also lead to other medical conditions including pulmonary hypertension and a higher risk of heart attack and stroke. People with nocturnal atrial fibrillation, and people with other symptoms of sleep apnoea should undergo a sleep study to diagnose this condition.
Treatment options for obstructive sleep apnoea include:
Weight loss - risk of sleep apnoea is highest in people who are overweight;
Sleep positional trainers - most sleep apnoea sufferers have worse breathing when sleeping on their back;
Mandibular advancement devices - these moulded plastic mouth guards are designed to stop the lower jaw slipping back during sleep;
Continuous positive airway pressure masks - various masks are available to deliver pressurised air overnight to keep the airways open and reduce snoring.
Nocturnal atrial fibrillation due to high vagal tone can be harder to treat, but identifying high vagal tone as the cause is important. Generally patients with vagal atrial fibrillation will do best with medications that don’t drop the heart rate too much.
Causes
Each heart beat is caused by the spread of electricity through the heart. Atrial fibrillation occurs when the usual spread of electricity in the upper chambers (atria) becomes disorganised and chaotic. This is generally triggered by extra beats in the pulmonary veins, which disrupt normal electrical function leading to chaotic electric activity. The causes of these extra beats are not always clear in each individual patient, but some common themes exist.
People are more likely to develop atrial fibrillation if:
They are overweight or obese
They drink alcohol
They have heart or blood vessel diseases, (high blood pressure, heart valve disease, diabetes)
They have obstructive sleep apnea
They have certain lung diseases
They have abnormal thyroid function
Certain types of endurance exercise can increase the chance of developing AF. In athletes different treatments may be needed to maintain the ability to compete or train.
Treatments
Treatment of atrial fibrillation has four main aims:
1. To reduce symptoms of AF;
2. To slow progression of the disease from paroxysmal (intermittent) AF to persistent (continuous) AF;
3. To identify and, if possible, to reverse the underlying cause for AF;
4. To reduce the risk of stroke
Treating the underlying cause is key to reducing atrial fibrillation symptoms and slowing disease progression. Tailored treatment packages, including weight loss, blood pressure control, and treating related conditions, can be highly effective. Additional treatments aimed at controlling heart rate or promoting a normal rhythm, may be necessary, including medications or cardioversion procedures for persistent atrial fibrillation.
For some patients, an AF ablation procedure can be used to maximise the chance of remaining in a normal rhythm in the medium term. In combination with other treatments, atrial fibrillation ablation can achieve freedom from atrial fibrillation symptoms over the medium term in up to 90% of patients with paroxysmal atrial fibrillation and 50-60% with persistent atrial fibrillation.
Atrial fibrillation is, however, a long term condition and stands a relatively high chance of returning at some point – even after successful initial treatment – if the underlying causes are not identified and treated.
The most urgent element of AF treatment is to reduce the risk of stroke. Patients with AF tend to have more strokes and worse strokes than people without AF, and therefore prompt action to reduce this risk by prescribing blood thinning drugs (if appropriate) is vital.
Complications
Atrial fibrillation contributes to 1 in 5 strokes in the UK. Strokes are caused by blood clots which interrupt blood supply to the brain, causing brain tissue death. Stroke symptoms depend on which part of the brain is affected. Disability after a stroke is common. Strokes in people with atrial fibrillation tend to be more severe, and can be life-threatening.
Stroke risk depends on age, gender, and medical history. If AF patients have a stroke risk of 1% or more per year, blood thinners are usually given to reduce the risk. However, exceptions exist to the 1% rule and the decision to start blood thinners is often nuanced.
Atrial fibrillation may also weaken the heart muscle and reduce heart pumping capacity, leading to heart failure. Atrial fibrillation and heart failure require personalised assessment and treatment, which may include medications, ablation procedures, or implantation of cardiac devices.