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Atrial fibrillation
Also known as AF · Afib
AF affects the heart's ability to pump blood effectively, leading to symptoms like palpitations, breathlessness, and fatigue. It can increase the risk of stroke and other heart-related complications, particularly among older adults.
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Overview
Atrial fibrillation (AF), often shortened to 'Afib', is the most common type of heart rhythm disturbance, known as an arrhythmia. It occurs when the electrical signals in the heart's upper chambers, called the atria, become disorganised and rapid. This leads to them quivering (fibrillating) instead of contracting in a coordinated way [PMID:32502157]. This irregular and often fast heartbeat can significantly impact the heart's efficiency in pumping blood to the rest of the body. In the UK, it is estimated that around 1.5 million people have been diagnosed with AF, and many more may be living with the condition undiagnosed. The lifetime risk of developing AF is approximately one in four.
Symptoms & clinical features
Many individuals with AF may not experience any notable symptoms, which can lead to delayed diagnosis. When symptoms do occur, they can vary widely in their presentation and severity. Common symptoms include a sensation of a fluttering or pounding heart, known as palpitations, and shortness of breath, especially during physical activity. People may also report feeling tired or lacking energy, experiencing dizziness, or light-headedness.
Other symptoms can include chest pain or discomfort, and generally feeling unwell. These symptoms often develop over time and may initially be intermittent, becoming more persistent as the condition progresses. Recognising these signs and seeking medical advice is important, particularly for those with known risk factors for AF.
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Affected organs
Atrial fibrillation primarily affects the heart, specifically the atria. The disorganised electrical activity within these upper chambers prevents them from contracting effectively, leading to inefficient blood flow into the lower chambers (ventricles). This reduced pumping efficiency can have broader implications for the cardiovascular system and other organs, such as the brain, due to the increased risk of blood clot formation and subsequent stroke [PMID:30623259].
Risks & severity
The severity of atrial fibrillation can range from occasional, brief episodes (paroxysmal AF) to persistent or long-standing forms of the condition. AF is considered a progressive condition for many, meaning paroxysmal AF may transition into a more continuous form over time. The primary concern with AF is the significantly increased risk of stroke, which can be up to five times higher compared to individuals without AF [PMID:30623259]. This is because blood can pool and form clots in the atria when they are not contracting effectively; if a clot travels to the brain, it can cause a stroke.
Other potential complications include heart failure, where the heart can't pump enough blood to meet the body's needs, and a reduced quality of life due to persistent symptoms. The risk of AF generally increases with age, and certain underlying health conditions, such as high blood pressure, diabetes, obesity, and other heart diseases, can also elevate an individual's risk. Alcohol consumption and obstructive sleep apnoea are also recognised risk factors.
Genetic causes
Atrial fibrillation is considered a complex or polygenic condition, meaning that it is influenced by a combination of multiple genetic factors working together, alongside environmental and lifestyle factors. While no single gene is solely responsible, research suggests that variations in several genes may contribute to an individual's susceptibility to developing AF.
Genes such as KCNN3, PITX2, and ZFHX3 have been identified in various studies as having associations with AF risk. For instance, KCNN3 plays a role in regulating potassium channels, which are crucial for maintaining the heart's electrical rhythm. PITX2 is involved in heart development and electrical patterning, while ZFHX3 is a transcription factor that influences cardiac function. Changes in these and other genes may alter the electrical properties of heart cells or the structure of the atrial tissue, increasing the likelihood of developing AF. However, the exact mechanisms by which these genetic variations contribute to the condition are still an area of active research.
Inheritance pattern
Atrial fibrillation generally follows a polygenic or complex inheritance pattern. This means that unlike conditions caused by a single gene change, AF risk is influenced by variations in multiple genes along with environmental exposures and lifestyle choices. Consequently, it is not passed down in a simple Mendelian pattern (like dominant or recessive inheritance).
If AF runs in a family, it indicates a potentially increased genetic predisposition within that family. However, having a family history does not guarantee that an individual will develop the condition, nor does its absence rule it out. Close relatives of someone with AF may have a slightly higher risk, but this often reflects a shared genetic background combined with similar environmental and lifestyle factors.
Diagnosis & testing
Diagnosing atrial fibrillation typically begins with a review of symptoms and a physical examination by a GP. The cornerstone of diagnosis is an electrocardiogram (ECG), which records the electrical activity of the heart. An ECG can confirm the presence of AF by identifying the characteristic irregular electrical patterns.
For intermittent AF episodes that may not be captured during a standard ECG, a GP may refer for extended heart monitoring using devices such as a 24-hour Holter monitor or an event recorder, worn at home. Further investigations, like echocardiograms (heart scans), may be performed to assess the heart's structure and function. For genetic testing in the context of arrhythmias, where an underlying genetic cause might be suspected, individuals are typically referred to an NHS clinical genetics service. This falls under the NHS National Genomic Test Directory, which uses specific 'R-codes' for eligibility criteria, currently R140 for inherited cardiac conditions, though AF is often more complex than a single-gene disorder.
Management & lifestyle
Managing atrial fibrillation focuses on two main goals: controlling the heart rate and rhythm, and reducing the risk of complications, particularly stroke. Treatment approaches are highly individualised and depend on the type of AF, its severity, and other existing health conditions. Medications such as beta-blockers or calcium channel blockers are often used to control heart rate, while other antiarrhythmic drugs may help restore a normal heart rhythm.
To prevent stroke, individuals with AF often require anticoagulation therapy, commonly with blood-thinning medications. Procedures like cardioversion (to reset the heart's rhythm) or catheter ablation (to destroy abnormal electrical pathways) may also be considered. Lifestyle modifications are a crucial component of management and include maintaining a healthy weight, regular exercise, limiting alcohol and caffeine intake, managing blood pressure, and quitting smoking. Ongoing care is typically managed by a GP in conjunction with a cardiologist, and patients may also benefit from consultations with heart rhythm nurses and genetic counsellors, particularly if there is a family history of heart conditions.
UK care pathway
In the UK, suspected atrial fibrillation typically leads to a GP referral to a cardiologist for specialist assessment and diagnosis. If there are indications of an inherited component, which is less common for AF than for some other cardiac conditions, a referral to an NHS clinical genetics service may be considered. Genetic counsellors play a vital role in explaining genomic test results, inheritance patterns, and risk to families. The NHS National Genomic Test Directory outlines the eligibility criteria for genomic testing for inherited cardiac conditions under specific 'R-codes', such as R140 for inherited cardiomyopathies and arrhythmias. However, for a polygenic condition like AF, extensive single-gene panel testing is less frequently pursued compared to conditions with clear monogenic inheritance.
Frequently asked questions
What is the main difference between AF and a normal heartbeat?
A normal heartbeat is regular and coordinated, with the upper and lower chambers of the heart working together efficiently. In atrial fibrillation, the upper chambers (atria) quiver quickly and irregularly, leading to an erratic and often fast heart rhythm that reduces the heart's pumping efficiency.
Can I prevent atrial fibrillation?
While you cannot prevent all forms of AF, you can significantly reduce your risk by adopting a healthy lifestyle. This includes maintaining a healthy weight, exercising regularly, avoiding excessive alcohol and caffeine, managing blood pressure and diabetes, and not smoking. Addressing conditions like sleep apnoea can also help reduce risk.
Is atrial fibrillation always serious?
The seriousness of AF varies from person to person. While some individuals may have mild symptoms and a good quality of life with appropriate management, AF increases the risk of serious complications like stroke and heart failure, especially if left untreated. Regular monitoring and adherence to treatment plans are crucial for managing these risks.
Will my children inherit atrial fibrillation from me?
Atrial fibrillation is considered a complex condition, influenced by multiple genetic factors and lifestyle choices. While having a close relative with AF might slightly increase your children's risk, it doesn't mean they will definitely inherit it. It is not passed down in a simple, predictable pattern like some single-gene disorders.
What should I do if I think I have AF symptoms?
If you experience symptoms such as persistent palpitations, shortness of breath, dizziness, or unusual tiredness, you should contact your GP. They can assess your symptoms, conduct initial tests like an ECG, and refer you to a cardiologist for further evaluation and diagnosis if needed.
References
- Mukai Y. Inflammation and atrial fibrillation. Journal of arrhythmia. 2024. PMID: 38333377
- Westermann D, Schrage B. Mitral stenosis and atrial fibrillation. Heart (British Cardiac Society). 2020. PMID: 32029526
- Mulder BA, Van Gelder IC, Rienstra M. Device-Detected Atrial Fibrillation. Circulation. 2019. PMID: 30880437
- Yim J, Krahn AD. Postoperative Atrial Fibrillation Begets Atrial Fibrillation. JACC. Clinical electrophysiology. 2024. PMID: 39084746
- Smaill BH. Fibrosis, myofibroblasts, and atrial fibrillation. Circulation. Arrhythmia and electrophysiology. 2015. PMID: 25900987
- Van Wagoner DR, Chung MK. Inflammation, Inflammasome Activation, and Atrial Fibrillation. Circulation. 2018. PMID: 30571523
- Santos IS, Bensenor IM. Cardiovascular health and atrial fibrillation. Heart (British Cardiac Society). 2021. PMID: 33858958
- Selim M, Diener HC. Atrial Fibrillation and Microbleeds. Stroke. 2017. PMID: 28916675