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What is Atrial Fibrillation (AF or AFib)? | Video
Atrial Fibrillation — AF or AFib for short — is one of the most common types of arrhythmia. The word arrhythmia might sound complicated, but it’s a fancy term used when the heart isn’t beating regularly. It could beat too fast, too slow, or just irregularly.
A heart in AF is like a clock that isn’t ticking right. Instead of ticking precisely every second, it’s erratic and unpredictable. Sometimes it ticks too fast, sometimes too slow, and sometimes just out of sync.
Typically, our hearts beat 60-100 times a minute when we’re at rest. But in cases of AF, the heart might beat over 100 times a minute — sometimes up to 175 times a minute — even when we’re not doing any strenuous activity. But not all AF cases are this extreme. Sometimes, the heart beats irregularly but at a normal speed. ‘rate-controlled Atrial Fibrillation’ is when we manage to keep the heart rate around or below 100 bpm despite the irregular rhythm.
What causes Atrial Fibrillation?
Various medical conditions and factors can trigger AFib, including:
Age and Sex
Age is a critical risk factor for AFib due to a combination of factors, including structural changes in the heart, a higher prevalence of heart disease, and the increased occurrence of other age-related health conditions. The prevalence of AFib is <2% in individuals younger than 60 but rises significantly with advancing age. Studies have shown that the risk of developing AFib doubles each decade after age 50. By age 80, over 15% of the population may be affected by AFib. At any age, AFib is more common in men. At any age, AFib is more common in men.
Hypertension, or high blood pressure, is a significant risk factor for AFib. Long-standing, uncontrolled high blood pressure can cause structural changes in the heart, such as left atrial enlargement (enlargement of the heart’s top chambers) or left ventricular hypertrophy (increased thickness of the heart’s muscle), which disrupt the normal electrical activity and promote the development of AFib. Additionally, hypertension can promote “inflammation”, which can damage the heart tissue, making it more susceptible to arrhythmias. Studies suggest that hypertension may increase the risk of AFib by up to 50%. Therefore, managing high blood pressure through lifestyle modifications and medications is a key strategy in preventing the onset of AFib.
Various heart diseases can precipitate AFib by inducing structural changes, most notably causing an enlargement of the atria (upper heart chambers). The most common culprits include heart valve disorders such as mitral valve regurgitation or stenosis, congenital heart defects, and cardiomyopathy. While coronary artery disease is not typically a direct cause of AFib, severe instances that lead to heart failure can contribute to the development of this irregular heartbeat.
Obstructive Sleep Apnea (OSA) is a significant risk factor for atrial fibrillation. This common yet often undiagnosed sleep disorder is characterized by repeated interruptions in breathing during sleep, leading to a drop in oxygen levels and fragmented sleep. These episodes can induce blood pressure and heart rate changes, increase sympathetic activity (the “fight or flight” response), and cause cardiac strain. This recurring nocturnal strain leads to structural and electrical changes in the heart, setting the stage for arrhythmias such as atrial fibrillation. The bidirectional relationship between OSA and AF is crucial to understand, as effective management of sleep apnea can contribute significantly to the control and prevention of AF.
Hyperthyroidism, a condition where the thyroid gland produces excessive thyroid hormone, is another significant player in the onset of atrial fibrillation. The overproduction of thyroid hormone accelerates the body’s metabolic processes, resulting in an increased heart rate and stronger contractions, which place significant stress on the heart. This added stress provokes structural and electrical changes in the heart, particularly in the atria, making the heart more susceptible to arrhythmias like AF. Furthermore, thyroid hormone also affects the electrical properties of atrial cells, thereby increasing the propensity for AF. The relationship between hyperthyroidism and AF underscores the importance of comprehensive endocrine evaluation in individuals with unexplained AF, ensuring that thyroid disorders are appropriately diagnosed and managed.
Diabetes and atrial fibrillation share a complex relationship. As a metabolic disorder, diabetes can cause a host of systemic complications, including microvascular and macrovascular diseases, impacting the cardiovascular system. Persistently high blood glucose levels can lead to the formation of substances that can result in cardiac fibrosis and increased susceptibility to AF.
Furthermore, insulin resistance, a central feature of type 2 diabetes, can contribute to cardiovascular complications, including hypertension and coronary artery disease, risk factors for AF. Diabetic autonomic neuropathy, another complication of diabetes, can also interfere with the autonomic control of heart rhythm, predisposing to arrhythmias.
The systemic changes brought about by diabetes can disrupt the normal function of the heart and promote conditions helping to the development of AF. This connection highlights the importance of good glycemic control not just for diabetes management but also as a strategy to reduce the risk of cardiovascular disease and arrhythmia.
Chronic kidney disease
Chronic kidney disease (CKD) and atrial fibrillation often go hand-in-hand, creating a challenging health scenario. CKD, characterized by long-term loss of kidney function, can lead to an accumulation of toxins and fluid in the body, which puts extra strain on the heart, precipitating AF. Moreover, the inflammatory and hormonal changes associated with CKD can further disrupt the heart’s normal rhythm. Therefore, effective management of CKD can help mitigate the risk of AF.
Chronic obstructive pulmonary disease (COPD) and atrial fibrillation (AF) frequently coexist, significantly impacting a patient’s quality of life. COPD, a progressive lung disease characterized by increasing breathlessness, can induce low oxygen (hypoxia) and high carbon dioxide levels (hypercapnia) in the body. These changes can stress the heart, leading to an increased risk of AF. The systemic inflammation associated with COPD can also contribute to the structural and electrical changes in the heart that predispose to AF.
Alcohol consumption can have a significant influence on the development of atrial fibrillation. Excessive casual drinking can cause a condition called “holiday heart syndrome“, leading to episodes of AF even in people without heart disease. Alcohol can induce changes in the structure and electrical properties of the heart, promote dehydration, and stimulate the release of stress hormones – all factors that can trigger AF. Furthermore, chronic heavy drinking can lead to high blood pressure and heart failure, two conditions commonly associated with AF. Moderation in alcohol consumption, therefore, plays a crucial role in maintaining heart health and minimizing the risk of AF.
Infections and inflammation
Infections and the resulting inflammatory response play a significant role in the development of atrial fibrillation. Systemic inflammation, an immune response to infection or injury, can change the heart’s structure and electrical properties, leading to AF. For instance, pericarditis or myocarditis, an inflammation of the heart sac or muscle usually caused by viral infections, can precipitate AF. Moreover, sepsis, a severe systemic infection, can cause a dramatic increase in heart rate and other stresses on the heart, which can also lead to AF.
Genetic factors play a significant role in the development of atrial fibrillation. Emerging research reveals that AF often runs in families, suggesting a hereditary component. Individuals with a family history of AF have approximately a 40% higher risk of developing the condition. Besides, certain genetic syndromes like Down syndrome and Marfan syndrome carry a higher risk of AF. However, our understanding of the genetic basis of AF still needs further research, given the disease’s complex nature with multifactorial and polygenic influences. With the remarkable advancements in genetic research, gene-targeted therapeutic strategies will transform into a tangible reality in the future.
What are the different types of atrial fibrillation?
The categorization of atrial fibrillation into paroxysmal, persistent, and permanent types is primarily helpful in guiding treatment decisions and helping predict patient outcomes. Each type has distinct characteristics and implications; understanding these can help determine the most effective treatment approach.
Paroxysmal AF is a type of AF where the episodes of irregular heartbeat start suddenly and then stop spontaneously. These episodes usually stop within 24 hours but can occasionally last up to a week. It’s called “paroxysmal” because it comes in bursts or paroxysms. These episodes can recur with varying frequency, from several times a day to once a year or even less frequently.
In this type of AF, the irregular heartbeats persist for over a week. They don’t resolve spontaneously and require medical intervention. This intervention can involve medications or a procedure called cardioversion, which aims to restore the heart’s normal rhythm.
This type occurs when attempts to restore a normal heart rhythm have failed or when the decision has been made to stop trying to restore a normal rhythm. The heart is permanently in AFib, and medical management is focused on controlling the heart rate and reducing the risk of complications such as stroke.
How Does AFib Affects a Person's Life?
Atrial fibrillation can impact your life in various manners. However, the severity and specific effects can differ depending on the individual, their overall health, and the management of the condition. Here are some ways AFib may affect you and your life:
Atrial Fibrillation Symptoms
Atrial Fibrillation presents a diverse array of manifestations, with the severity and type of symptoms varying widely among individuals. Some people might experience debilitating symptoms, while others may be completely asymptomatic, discovering their diagnosis only through proactive health screenings or via alerts from their smart wearables (see Fig.1).
Regrettably, there are instances where the initial diagnosis of AF comes only after the occurrence of a stroke. It’s important to note that while AF may not always produce noticeable symptoms, its presence can still significantly impact an individual’s health.
Typical symptoms of AF include:
- Fast heart rate (Tachycardia) and Palpitations
- Fatigue and Weakness
- Dizziness or Lightheadedness
- Reduced exercise capacity
- Increased urination
- Mild shortness of breath (dyspnea)
In some cases, patients may experience more severe symptoms, including shortness of earth at rest, chest pain, and presyncope (feeling faint).
Fig.1 – These photos illustrate the notifications from a patient’s smartwatch, advising her to consult her doctor because her device had detected AFib. This 63-year-old female, who stays active with Zumba three nights a week and takes no medication, had no symptoms whatsoever. It was after her smartwatch detected the AFib for the third time that she visited her doctor, who confirmed the diagnosis with an ECG (shown on the right). Had it not been for the early detection enabled by her smartwatch, her first medical encounter might have been in a hospital following an unexpected stroke. (Click on the image to enlarge)
Risk of Stroke
AFib significantly increases the risk of stroke. Studies have shown that people with AF are about 5 times more likely to experience a stroke than those without the condition. This elevated risk is due to the fact that AF can cause blood to pool and clot in the heart’s top chambers — atria — leading to the formation of blood clots. These clots can then travel to the brain, causing a stroke. However, the actual risk can vary among individuals based on various factors such as age, presence of other diseases (like diabetes, hypertension, or heart failure), and prior history of stroke or mini-strokes.
In AFib, the heart beats irregularly and often rapidly. When the heart beats too fast over an extended period, it can become weakened and less efficient in pumping blood, leading to “tachycardia-induced cardiomyopathy”.
Tachycardia-induced cardiomyopathy is a specific type of heart muscle weakness — cardiomyopathy — that results from sustained fast heart rates. This condition is generally reversible if the heart rate is controlled, but it can lead to severe and potentially life-threatening heart failure if left unmanaged.
Treatment and lifestyle changes
AFib management requires diligence, adaptation, and patience, as it involves a multi-faceted approach. This includes frequent doctor appointments, taking multiple medications, and procedures such as cardioversion, catheter ablation, or pacemaker implantation. Beyond clinical interventions, lifestyle modifications play a crucial role in AF management. Adherence to a healthy diet, establishing a regular exercise routine, effectively managing stress, shunning tobacco and limiting alcohol consumption, and treating conditions like obstructive sleep apnea (OSA), can all contribute to managing this complex condition. Effective management of AFib necessitates a robust commitment to these significant changes, understanding that the journey may require multiple medication adjustments and potential hospitalizations.
Living with Atrial Fibrillation and the Emotional Impact
AFib diagnosis can have a significant emotional impact, invoking various feelings and challenges. The condition often brings about anxiety and fear due to its unpredictability and potential complications, such as stroke or heart failure. The daily management of the disease, coupled with necessary lifestyle changes and possible symptoms, can lead to depression and chronic stress. These feelings can be compounded by regular medical appointments, potential treatment side effects, and the financial implications of managing a chronic condition. Further, individuals might be frustrated and angry if AF interferes with their usual activities or causes bothersome treatment side effects. All these aspects underscore the crucial need for comprehensive care in managing AF, which includes addressing mental health and offering strategies for effective stress management.
Keep in mind that with proper management and care, many people with AFib can lead active and fulfilling lives. It is essential to work closely with your healthcare team to create a personalized plan to manage your condition effectively.
Which initial evaluations and tests should you expect following an Atrial Fibrillation diagnosis?
The necessity of tests largely depends on the symptoms and concerns. Typically, after a physical exam, initial tests include an ECG (Electrocardiogram), an Echocardiogram, and a complete blood test. The ECG determines your heart rate, confirms the diagnosis of Atrial Fibrillation, and can show other conduction or ischemic abnormalities. The Echocardiogram evaluates heart function and can detect potential underlying valvular diseases which can lead to AFib, like Mitral Valve Regurgitation. Blood work can show other possible abnormalities leading to AFib, like thyroid diseases – hyperthyroidism.
Additional assessments, such as stress echocardiogram, may be needed to examine coronary arteries based on risk factors. Managing heart disease risk factors like hypertension, high cholesterol, obesity, and diabetes is crucial.
Is Atrial Fibrillation Potentially Life-Threatening?
Atrial fibrillation is generally not life-threatening in itself, but it can lead to serious complications that may be life-threatening if left untreated or poorly managed. Some of these complications include:
- Stroke: AFib increases the risk of stroke, as it can cause blood to pool in the heart’s upper chambers, forming blood clots. A clot travelling to the brain can cause a stroke, which can be life-threatening or lead to long-term disability.
- Heart failure: Over time, the rapid and irregular heartbeat in AFib can weaken the heart muscle, increasing the risk of developing heart failure, a condition in which the heart cannot pump blood efficiently. Heart failure can be life-threatening if not managed properly.
How important is heart "rhythm" control in atrial fibrillation?
Rhythm control in atrial fibrillation is an important aspect of managing the condition. It can help alleviate symptoms, improve quality of life, and potentially reduce the risk of complications. The significance of rhythm control in AFib management varies depending on individual factors, such as the severity of symptoms, other health conditions, and overall treatment goals.
Two main strategies for managing AFib are rate control and rhythm control. While rate control aims to slow down the heart rate to a safe level, rhythm control focuses on restoring and maintaining a normal sinus rhythm. Rhythm control can be crucial for some patients, particularly those with the following:
- Severe symptoms: Restoring a normal heart rhythm can alleviate symptoms such as palpitations, shortness of breath, dizziness, and fatigue, improving the patient’s quality of life.
- Heart failure: Patients with heart failure may benefit from rhythm control, which can help improve the heart’s ability to pump more efficiently.
- Inadequate rate control: When rate control medications do not adequately manage the condition, rhythm control may be necessary.
However, rate control may be sufficient in managing the condition for some patients, especially those with no or mild symptoms and well-tolerated AFib.
Two electrocardiograms showing showing the difference between sinus rhythm and atrial fibrillation.
Frequently asked questions:
Can coronary artery disease cause Atrial Fibrillation?
Coronary artery disease (CAD), while primarily associated with conditions like angina and heart attacks, can indirectly contribute to the development of AF. CAD can lead to situations that increase the strain on the heart, such as heart failure resulting from a heart attack. This state of cardiac dysfunction can increase the risk of atrial fibrillation.
Moreover, CAD and AF often share common risk factors, such as hypertension, diabetes, obesity, and smoking, so they may frequently co-exist. This can lead to a complex interplay of conditions that exacerbate the other. Having said that, while CAD can be a contributing factor, it is not one of the most direct or common causes of AF, which are typically conditions that directly affect the structure and function of the atria (heart’s top chambers), such as hypertension, valve diseases, or heart failure.