Atrial Fibrillation – Causes, Symptoms, Treatments

What is Atrial Fibrillation?

Atrial fibrillation, often abbreviated as AFib or AF, is a type of irregular heartbeat (arrhythmia) that starts in the upper chambers of your heart (atria). In a normal heart, electrical signals coordinate the beating of your heart. With AFib, these signals become disorganized, causing the atria to quiver instead of beating effectively.

This quivering motion reduces the heart’s ability to pump blood efficiently throughout the body. AFib can occur in single episodes or continuously. If left untreated, AFib can increase your risk of serious complications, such as stroke, heart failure, and even death.

Atrial fibrillation (AFib) is the most common type of heart arrhythmia, affecting millions of people worldwide. Its prevalence increases with age, with around 10% of people over 80 experiencing AFib. Estimates vary, but globally, around 46.3 million individuals were diagnosed with AFib in 2016. In the United States alone, at least 3 to 6 million people have AFib, with projections reaching 6 to 16 million by 2050.

Symptoms of Atrial Fibrillation 

Not everyone with AFib will experience symptoms. Some people may not even know they have it. However, some common symptoms of atrial fibrillation include:

• Irregular heartbeat: This is the most common symptom of AFib. Your heart may beat too fast, too slow, or irregularly. You may feel like your heart is fluttering, flopping, or racing.
• Fluttering sensations in your chest (palpitations): A fluttering or pounding sensation in the chest is a common symptom of AFib. Some people describe it as feeling like their heart is racing or skipping beats.
• Weakness or fatigue: Feeling weak or having a general sense of malaise can occur with AFib, especially during episodes of rapid or irregular heartbeat. Also feeling excessively tired or lacking energy is a frequent symptom of AFib. The irregular heartbeat can disrupt normal blood flow, leading to fatigue.
• Shortness of breath: Difficulty breathing or feeling short of breath, especially during physical activity, is another common symptom. This occurs because the heart is unable to pump blood effectively, leading to decreased oxygen delivery to the body.
• Lightheadedness or dizziness: AFib can cause feelings of dizziness or lightheadedness, particularly when standing up quickly or exerting oneself. This symptom may result from decreased blood flow to the brain.
• Chest pain (although this is less common): Some people with AFib experience chest pain. If you have chest pain, it’s important to see a doctor right away to rule out a heart attack.
• Fainting (syncope): In severe cases, AFib may cause fainting episodes due to decreased blood flow to the brain during periods of rapid heartbeat.

Risk Factors for Atrial Fibrillation

Chronically high blood pressure puts long-term strain on the heart, causing the walls of the atria to enlarge and stiffen. This stretching and stiffening disrupts the normal electrical signals in the atria, making them more prone to irregular firing and AFib.

Various heart conditions can damage the heart muscle or electrical pathways in the atria, leading to AFib. Coronary artery disease, for example, can reduce blood flow to the heart muscle, including the atria, causing scarring and abnormal electrical activity. Heart failure weakens the heart muscle, impacting its ability to pump blood efficiently. This stress can affect the atria, increasing the risk of AFib. Heart valve problems, particularly those affecting the mitral or tricuspid valves, can disrupt blood flow within the heart and contribute to AFib.

Obesity is a complex risk factor for AFib. Excess weight puts a strain on the heart, similar to high blood pressure. Fat tissue can also release inflammatory chemicals that contribute to changes in the heart structure and electrical activity, promoting AFib.

During sleep apnea episodes, breathing repeatedly stops and starts, reducing oxygen levels in the blood. This oxygen deprivation puts stress on the heart and can trigger AFib episodes. The repetitive strain from sleep apnea events may also contribute to changes in the heart structure and electrical activity over time, increasing the risk of AFib.

Chronically high blood sugar levels in diabetes can damage blood vessels and nerves throughout the body, including those supplying the heart. This damage can lead to changes in the heart muscle and electrical system, increasing the risk of AFib. Diabetes can also contribute to inflammation in the body, further promoting Afib development.

An overactive thyroid (hyperthyroidism) produces excess hormones that can increase heart rate and disrupt the electrical signals in the heart, potentially triggering AFib episodes.

Binge drinking or heavy alcohol use can have a direct effect on the heart muscle, weakening it and disrupting its electrical signals. This can trigger AFib episodes or worsen existing AFib. Alcohol can also interact with certain medications and worsen AFib symptoms.

Smoking damages the heart and blood vessels, similar to other cardiovascular risk factors. The chemicals in cigarettes can also disrupt the electrical signals in the heart, increasing the risk of AFib.

Possible Complications of AFib

Atrial fibrillation (AFib) can lead to several serious complications if left untreated. The irregular heartbeat associated with AFib is the root cause of these complications. 

Stroke is the most concerning complication of AFib. During AFib, the irregular beating of the atria disrupts the normal blood flow within them. This can cause blood to pool and clot in the atria. If a clot breaks loose and travels to the brain through the bloodstream, it can block an artery and cause a stroke. The risk of stroke is significantly higher in people with AFib compared to those with a normal heart rhythm.

The irregular contractions of the atria don’t allow for complete emptying of blood, creating a stagnant environment where clots can form. The presence of damaged or inflamed atrial tissue, sometimes seen in AFib, can further increase clot formation.

Chronically irregular heartbeats from AFib can weaken the heart muscle over time. This weakening reduces the heart’s ability to pump blood efficiently throughout the body, eventually leading to heart failure.

The disorganized contractions of the atria decrease the heart’s overall pumping efficiency. Over time, this inefficiency strains the heart muscle, leading to weakening and potential enlargement.

Afib can also contribute to fatigue, shortness of breath, and cognitive decline due to reduced blood flow and oxygen delivery to various organs. In some cases, it may worsen pre-existing angina (chest pain) or trigger new episodes.

How is Atrial Fibrillation Diagnosed?

Diagnosing atrial fibrillation (AFib) often involves a combination of procedures to assess your heart’s electrical activity, structure, and overall function.

An Electrocardiogram (ECG) is a non-invasive test that measures your heart’s electrical activity using electrodes placed on your chest, limbs, and sometimes your back. An ECG trace can reveal characteristic patterns of irregular heartbeats that indicate AFib. While a standard ECG might not capture a fleeting AFib episode, it’s a crucial first step and can be helpful in identifying established AFib.

The Holter Monitor is a portable device that continuously records your heart’s electrical activity for a specific period, typically 24-48 hours.The monitor is worn while going about your daily activities, allowing doctors to capture any AFib episodes that might not show up on a standard ECG. This extended monitoring period provides valuable information for confirming AFib, especially for those with occasional episodes.

Similar to a Holter monitor, the portable event monitor device records the heart rhythm, but for a longer duration (weeks to months). It’s typically used for people who experience infrequent AFib symptoms. The event monitor has a button you can press to capture your heart rhythm when you experience symptoms, helping doctors correlate symptoms with specific heart rhythm patterns.

The Echocardiogram (Echo) is a painless ultrasound imaging technique that uses sound waves to create detailed images of your heart structure, including the valves and chambers. An echo can help identify underlying heart conditions that might be contributing to AFib, such as enlarged atria or weak heart valves. It can also assess your heart’s pumping function, which can be helpful in determining the overall health of your heart and guiding treatment decisions.

Routine blood tests might be ordered to check for underlying conditions that can increase AFib risk, such as thyroid problems, electrolyte imbalances, or anemia. These tests, while not directly diagnostic of AFib, can provide valuable information for guiding your overall treatment plan.

The Exercise Stress Test monitors your heart rhythm and electrical activity while you exercise on a treadmill or stationary bike. The goal is to see how your heart responds to physical exertion, which can sometimes trigger AFib episodes in susceptible individuals. An abnormal stress test result might suggest a higher risk of AFib, especially if combined with other findings.

An Electrophysiological Study (EPS) is a specialized test that is typically used in complex cases or when planning specific ablation procedures to treat AFib. During an EPS, thin catheters are inserted into your heart through blood vessels to directly record electrical signals within the atria. This detailed mapping helps identify the specific areas in the atria causing the irregular heartbeats.

How is Atrial Fibrillation treated?

Atrial fibrillation (AFib) treatment focuses on two main goals. The first is stroke prevention, which is paramount as AFib significantly increases stroke risk. The second is minimizing symptoms like heart palpitations, fatigue, and shortness of breath. Several methods are used for this purpose. 

1. Medications:
   • Anti-coagulants (blood thinners): These medications like warfarin, dabigatran, or rivaroxaban are crucial for preventing blood clots that can cause stroke. The specific type and duration of anticoagulation depend on your individual stroke risk factors.
   • Anti-arrhythmic medications: These medications aim to regulate your heart rhythm and restore a normal heartbeat. While not always successful in maintaining normal rhythm, they can help control the heart rate and reduce symptoms. Beta-blockers and certain antiarrhythmic drugs fall into this category.
2. Catheter Ablation:
   • This minimally invasive procedure uses radiofrequency energy or extreme cold to target and destroy small areas of tissue in the heart that are causing the irregular electrical signals.
   • Catheter ablation aims to create electrical blockages that prevent abnormal signals from triggering AFib episodes.
   • It’s most effective for certain types of AFib and may require repeat procedures in some cases.
3. Electrical Cardioversion:
   • This procedure uses an electric shock delivered through patches on your chest or paddles placed on your chest wall to reset your heart rhythm back to normal sinus rhythm.
   • Cardioversion is typically used for recent-onset AFib episodes and is often combined with medications to maintain normal rhythm long-term.
4. Lifestyle Modifications:
   • Losing weight, maintaining a healthy diet, exercising regularly, managing stress, and limiting alcohol intake are crucial for overall heart health and can potentially reduce AFib episodes and improve symptoms.
   • Quitting smoking is also essential as smoking worsens AFib and increases stroke risk.

What Medication is Most Often Prescribed for Atrial Fibrillation?

The most common preventive measure prescribed for individuals with atrial fibrillation (AFib) to reduce their stroke risk is anticoagulant medication, often referred to as blood thinners.

These medications work by interfering with the blood clotting process, making it less likely for clots to form in the atria and potentially travel to the brain, causing a stroke.

Here’s a deeper look at how the choice of anticoagulant is determined:

Types of Anticoagulants for AFib:

There are two main categories of anticoagulants used for AFib:

• Vitamin K Antagonists (VKAs): Warfarin is the most well-known VKA. It works by blocking the action of vitamin K, a vitamin essential for blood clotting.
• Non-Vitamin K Antagonist Oral Anticoagulants (NOACs): This category includes medications like dabigatran, rivaroxaban, apixaban, and edoxaban. They work by targeting specific clotting factors directly.

Choosing the Right Anticoagulant:

The decision on which anticoagulant is prescribed considers several factors, including:

• Stroke Risk: Doctors will assess your individual risk of stroke using scoring systems like CHA₂DS₂-VASc. This score takes into account factors like age, history of stroke or transient ischemic attack (TIA), high blood pressure, diabetes, congestive heart failure, and vascular disease. A higher score indicates a greater stroke risk.
• Bleeding Risk: Certain factors like a history of bleeding events, recent surgery or trauma, and specific medical conditions can increase your risk of bleeding complications with anticoagulants.
• Individual Preferences: Convenience of dosing and the need for regular monitoring (required with VKAs) are also factors considered during discussions with your doctor.

General Considerations:

• NOACs are often the preferred choice for Afib patients due to several advantages:
  • They typically have a more predictable anticoagulant effect compared to VKAs.
  • They don’t require frequent monitoring of blood clotting time (INR) like VKAs.
  • They may have a lower risk of bleeding complications in some cases.
• However, VKAs may still be preferred in certain situations:
  • If you have a mechanical heart valve, VKAs are generally the recommended choice.
  • If you have a high risk of bleeding or difficulty adhering to medication schedules, VKAs might be a better option.