Atrial fibrillation (AFib or AF) is the most common abnormal heart rhythm. In the UK, over one million people having this type of irregular heart beat, while in the US, up to 6 million people could have AFib. Atrial fibrillation is linked with high blood pressure, and if you have both hypertension and atrial fibrillation your risk of developing a stroke at least five-fold higher than normal if both conditions are poorly controlled. What’s more, stroke severity is usually greater if it is associated with AF. That’s why it’s so important to check if you have AFib so you can receive appropriate treatment to reduce your long-term chance of complications.
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Do you have atrial fibrillation?
To check whether or not you have atrial fibrillation simply check your pulse either at the wrist or the side of your neck. A normal heart rate is less than 100 beats per minute and has a regular rhythm. If you have AF, your pulse will be faster than 100 beats per minute (often as high as 160 to 180 beats per minute) and have an irregular rhythm. While it’s perfectly normal for your heart to skip a beat every now and then, when you have atrial fibrillation your heart beats irregularly the whole time with no pattern at all. If you think you could have atrial fibrillation, see your doctor as soon as possible.
Heart rate monitors that can detect atrial fibrillation are available from Amazon.co.uk and Amazon.com and some are surprisingly cheap although the more expensive versions are usually more robust and accurate.
What is atrial fibrillation?
Atrial fibrillation is an irregular heart rhythm that results from disorganised electrical activity in the atria (upper chambers) of the heart. This is thought to result from rapidly firing cells in the wall of the left atrium (upper chamber) which causes the atria to contract in a disorganised way.
The pulse rate in someone with untreated AF is usually between 160 and 180 beats per minute, although it may be slower in elderly people.
Atrial fibrillation is classified according to how long episodes of AF last.
- Paroxysmal AF is diagnosed when recurrent episodes last longer than 30 seconds but less than 7 days (often less than 48 hours) before stopping on their own.
- Persistent AF is diagnosed when episodes last longer than 7 days, after which time they are unlikely to stop on their own without treatment.
- Permanent AF is diagnosed when the abnormal rhythm is longstanding (usually more than 1 year) or when electric shock treatment (cardioversion) does not correct the rhythm.
Atrial fibrillation symptoms
If symptoms do occur with AF, these may include feeling light-headed or dizzy, fainting, chest discomfort, experiencing palpitations (a fluttering or jumping sensation in the chest) or breathlessness. You may also notice reduced exercise tolerance, feeling tired and under the weather, or passing water more often than usual due to the release of a hormone (atrial natriuretic peptide) from the heart during an episode of AF.
Atrial fibrillation causes blood to pool within the atria, which can lead to blood clotting. If a blood clot forms within the heart this can be pumped out and travel to the brain. The first sign of having atrial fibrillation may be experiencing a TIA (transient ischaemic attack, or mini stroke) or a full-blown stroke.
Causes of atrial fibrillation
There is an identifiable cause of atrial fibrillation in most people, with only 11% having what’s known as ‘lone AF’ with no obvious underlying trigger.
The most common causes of atrial fibrillation are ischaemic heart disease (angina, previous heart attack), hypertension, valvular heart disease and having an overactive thyroid gland (hyperthyroidism). Some diet and lifestyle factors are also associated with AF, such as excessive caffeine intake, excessive alcohol intake and obesity (which places greater strain on the heart).
Atrial fibrillation and hypertension
The number of people with atrial fibrillation, or AFib, has increased by 20% in just five years. While this may partly be due to improved awareness and better diagnosis, the rise is partly attributed to excess drinking, obesity and high blood pressure.
High blood pressure increases the chance of developing atrial fibrillation as having poorly controlled high blood pressure means the heart has to pump harder to push blood out into the body against a higher pressure. This can lead to thickening of the muscle in the left ventricle of the heart (hypertrophy), and stretching of the ventricle. High blood pressure also hastens hardening and furring up of the arteries and affects kidney function, all of which are recognised risk factors for AF. As a result, an estimated one in six cases of AF is directly due to having uncontrolled high blood pressure, and someone with hypertension is 70% more likely to develop atrial fibrillation than someone with normal blood pressure.
Achieving good control of your blood pressure reduces strain on your left ventricle as the pressure against which it has to pump blood around the body is lower. This can significantly lower your risk of developing atrial fibrillation. If you already have AF, then good blood pressure control to reach your recommended target, can reduce stretching of your heart and, alongside standard anticoagulation treatment, may improve long-term survival.
Atrial fibrillation treatment
AF is diagnosed on a heart tracing (ECG) which will show an irregular pattern of heart beats with no preceding small p wave. The heart rate is usually over 150 beats per minute, but may be lower in people without symptoms.
Atrial fibrillation medication includes drugs to slow your heart rate (eg a beta-blocker or calcium-channel blocker), an assessment of your stroke risk (based on your age, gender, blood pressure, and past medical history such as vascular disease, diabetes or previous stroke/TIA).
If your risk of stroke is raised, your doctor will offer anticoagulation treatment which is designed to reduce the risk of abnormal blood clots. Anticoagulation thins the blood and can reduce the risk of a stroke by around two-thirds, although the benefits must be weighted against the risk of bleeding.
At one time, the only anticoagulant available was warfarin, which requires regular blood monitoring, and can interact with other drugs and diet. Newer, novel anticoagulant (NOAC) drugs are now available, such as dabigatran, rivaroxaban and apixaban, which have made treatment less onerous.
Taking your anticoagulation treatment as prescribed is vital, especially with a NOAC, as their anticoagulant effect fades rapidly after 12 to 24 hours, depending on the drug. Warfarin acts for longer, so that some blood thinning effect is retained for 48 to 72 hours after missing a dose.
If anticoagulation is unsuitable for you, for example due to an increased risk of bleeding, then your doctor may offer a combination of aspirin and clopidogrel.