Atrial fibrillation (AF) is an extremely common problem, and can affect people in many different ways. It affects around 1 in 200 people in the general population, and is increasingly common with advancing age with around 1 in 10 people suffering with AF at the age of 80 years old, and 1 in 4 at the age of 85 years. While some patients have no awareness that they are in AF and feel completely well, others suffer with often severe symptoms that can be very intrusive on daily life. Common symptoms include palpitations (an awareness of the heart beating irregularly or fast, fluttering or pounding sensation in the chest), breathlessness, lack of energy and fatigue. These symptoms can come and go intermittently in some people, while others have symptoms all of the time. This often relates to the ‘type’ of AF that is occurring. AF is categorised in to 3 different ‘types’:
- Paroxysmal AF – Patients suffer with intermittent episodes of AF. These episodes can vary in duration, lasting from a few seconds or minutes to several hours. To be classed as ‘paroxysmal AF’ episodes must last less than 7 days. Between attacks of paroxysmal AF, patients often feel well although following an episode many patients feel very tired and fatigued. Patients with paroxysmal AF often describe a sudden onset of rapid palpitations or fluttering in the chest. It can cause the blood pressure to drop suddenly, and provoke symptoms of dizziness.
- Persistent AF – Episodes are much longer lasting, and are ongoing for more than 7 days continuously. Although the AF is constant patients don’t always have palpitations all of the time, but often will feel breathless when they try to exert themselves, or find that they have a lack of energy and fatigue easily. Some people begin with paroxysmal episodes of AF, which gradually get longer and longer before becoming persistent. Once patients haver persistent AF, successful treatment to restore the normal heart rhythm can be more difficult and hold lower success rates. Getting treated promptly can increase the success rate of restoring the normal heart rhythm.
- Permanent AF – Permanent AF is defined as AF that is present all of the time, similar to that of persistent AF. However, in permanent AF there is an acceptance that AF is going to constantly occur. In many instances this is because AF has been going on for many years, and the patient does not have any symptoms. It might also be because previous episodes have failed to treat the AF and restore the normal heart rhythm. Quite often, the reason that it is not possible to treat the AF is the result of many years of being in AF. The longer a patient is in AF, the more difficult it is to restore them to a normal heart rhythm.
What is Atrial Flutter?
Atrial flutter is another common type of abnormal heart rhythm. It is similar to AF in that it can cause the same symptoms, and the same treatments can be applied to manage it. It is not uncommon that patients have both atrial flutter and atrial fibrillation. Atrial flutter is more ‘organised’ than AF, and has a classical appearance on an electrocardiogram (ECG). There are different types of atrial flutter, which can occur in either the right or left atrium. It is more common that it occurs in the right atrium, and this is known as ‘typical atrial flutter’. There is an organised circuit of electrical activation that occurs in the atrium. This can be treated with medications, electrical cardioversion, and catheter ablation (further information on these treatments below). Catheter ablation for atrial flutter is highly successful, and is a more simple procedure for atrial flutter than it is for AF.
Similar to atrial flutter, atrial tachycardia is a more organised abnormal rhythm than AF. It can be the result of an abnormal electrical circuit or a small area in the heart ‘firing off’ abnormal impulses. Again, the same treatments can be applied to manage this condition.
What causes AF?
The normal heart rhythm depends on regular electrical activity of the heart’s natural pacemaker cells – the sinus node. The sinus node is in the right upper chamber of the heart and usually ‘fires’ at about 60-100 beats per minute but it can be faster (during exercise, for example). The electrical impulse spreads through the heart to create a coordinated contraction between the upper and lower chambers. In AF, the normal rhythm is lost due to abnormal electrical activity from an area around the pulmonary veins. Most people have 4 pulmonary veins, which ‘plumb’ in to the back of the left atrium. The pulmonary veins bring blood from the lungs to the heart. In AF, there are regions in the pulmonary veins that ‘fire off’ abnormal impulses, which are able to make people go out of their normal heart rhythm and in to AF. This results in a chaotic rhythm (AF) in the upper chambers of the heart which stops them contracting effectively. As the electrical impulse is transmitted to the lower chambers it causes the heart to beat in an irregular, often fast manner that responds poorly to the needs of the body.
What is the risk of stroke?
It is important to recognise and diagnose AF because it can result in an increased risk of stroke. When the atrium is in AF, it does not pump blood as effectively, which can result in small blood clots forming in the chamber. These can move to different organs in the body, and if they move to the brain this can result in a stroke or mini-stroke (TIA – Transient Ischaemic Attack). A risk scoring calculation, called the CHA2DS2-VASc score, is used to determine how high the patients risk of stroke is. CHA2DS2-VASc allows points to be scored for different risk factors and is an acronym which stands for:
C = Congestive cardiac failure (heart failure or ‘impaired left ventricular function’)
H = Hypertension (High blood pressure)
A2 = Age (>65 years -1 point, >75 years – 2 points)
D = Diabetes
S2 = Stroke or TIA (Transient Ischaemic Attach, or ‘mini-stroke’ – 2 points)
V = Vascular disease (heart attack or other vascular disease)
A = Age (>65 years – 1 point)
Sc = Sex category (female = 1 point)
A point is scored for each of these categories, except age >75 and previous stroke or TIA which score 2 points. If 1 or more point has been scored, it is recommended that patients are started on an anticoagulant (‘blood thinner’) to reduce the risk of stroke. The only exception to this is a single point for being female. In this situation it would not be necessary to start an anticoagulation. The most common anticoagulant to be initiated in the past was warfarin. Although this is still sometimes used, we now have more modern drugs which are easier to control and do not need constant blood tests to check levels. These drugs are called NOACs or DOACs (Novel Oral Anticoagulants or Direct Oral Anticoagulants). Aspirin does not have any beneficial effect at reducing the risk of stroke for patients with AF, and is no longer used as an alternative to anticoagulation.
How is atrial fibrillation treated?
There are 2 key aspects of treatment for AF. The first is protection from stroke, which is done with anticoagulant medications. The second aspect is treatment of the abnormal heart rhythm (AF) where the aim is to manage the frequency of the heart contraction rate (referred to as “Rate Control”) and/or the abnormal heart rhythm itself (referred to as “Rhythm Control”).
- Rate Control – This strategy is often tried first. It does not restore normal rhythm but aims to reduce the rate at which the ventricles contract. Heart rates in AF can be very variable and generally tend to be fast which can put stress on the heart and reduce the ability to pump effectively.
- Rhythm Control – This is the preferred strategy in patients who continue to have symptoms despite attempts to control the heart rate. The aim is to restore regular rhythm and contraction in all chambers of the heart. This can be done with electric treatment (cardioversion), together with long-term tablet medication or by a more definitive ablation procedure.
How is the heart rhythm controlled?
There are three main methods to control the heart rhythm. These include:
- Medication – There are a variety of different drugs that can be used to control the heart rhythm. These are referred to as antiarrhythmic drugs, and have the ability to either restore the heart rhythm to normal, or maintain it in a normal rhythm. These drugs are sometimes taken every day in people that have very frequent symptoms, or in those that require medications daily to maintain the normal heart rhythm. Other patients might only have a few episodes of AF per year, and prefer to only take medication at the time of an attack of AF in order to restore the normal heart rhythm. This medication technique is called ‘pill-in-pocket’, where a patient has a supply of a medication that they can use as and when it is required.
- Electrical cardioversion – This treatment is only of benefit for people that are in AF for a long period of time, and is not used for patients with paroxysmal AF. Patients are sedated or given a short general anaesthetic, and a specially timed electric shock is passed between two patches that are attached to the chest. This is aimed at resetting the rhythm to normal. This can work for some patients, although long term success rates from this are often poor. Approximately 50% of patients that have an electrical cardioversion for AF will go back in to AF within 1 year. For more information CLICK HERE.
- Catheter Ablation – There are two main types of catheter ablation that can be done to treat AF. They relate to the type of energy that is used to cauterise regions of the heart that are responsible for AF. These are ‘cryoablation’ or ‘radiofrequency ablation’. Procedures can be done under local anaesthetic or under general anaesthetic. For more information about catheter ablation CLICK HERE.