Atrial Fibrillation (AFib): Symptoms, Causes & Treatment Guide
Updated: 5 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What Is Atrial Fibrillation (AFib)?
Atrial fibrillation (AFib) is an irregular and often very rapid heart rhythm caused by chaotic electrical signals in the heart's upper chambers. It may cause a fast pounding heartbeat, shortness of breath, or dizziness — and some people notice no symptoms at all. AFib is usually not life-threatening on its own, but it raises the risk of blood clots and stroke, so it needs proper treatment.
What the research says
Cutting back on alcohol reduced AFib recurrences in regular drinkers. In a randomized trial of 140 adults with AFib who drank 10 or more standard drinks a week, AFib returned in 53% of those who abstained versus 73% of those who kept drinking (hazard ratio 0.55, 95% CI 0.36–0.84), and the share of time spent in AFib over 6 months was lower in the abstinence group. (Voskoboinik et al., N Engl J Med, 2020) [3]
For AFib with weakened heart pumping, catheter ablation outperformed medicines. A meta-analysis of 7 randomized trials (1,163 patients with AFib and a left ventricular ejection fraction of 45% or less) found ablation linked to lower all-cause mortality (risk ratio 0.52, 95% CI 0.37–0.72), a 4.8-point greater improvement in ejection fraction, and fewer heart-failure hospitalizations than medical therapy. (Cui et al., Arq Bras Cardiol, 2024) [4]
TL;DR
What it is: An irregular, often rapid heartbeat caused by chaotic electrical signals in the heart's upper chambers.
Symptoms: Fast pounding heartbeat, chest pain, shortness of breath, dizziness, fatigue, weakness; some people have no symptoms.
Main risk: Blood clots that can lead to stroke; also increases the risk of heart failure.
Cause: Most often changes in the heart's structure, plus lifestyle triggers like alcohol, caffeine, and smoking.
Diagnosis: ECG (electrocardiogram) is the main test, supported by monitors, blood tests, and imaging.
Treatment: Medicines, cardioversion (resetting the rhythm), and ablation procedures; lifestyle changes help prevent it.
Atrial Fibrillation at a Glance
Topic | Quick Summary |
What it is | An irregular and often rapid heart rhythm (arrhythmia) from chaotic signals in the upper heart chambers |
Most common symptoms | Fast pounding heartbeat, shortness of breath, dizziness, fatigue, chest pain, weakness |
Serious complication | Blood clots in the heart that increase the risk of stroke and heart failure |
Most common cause | Changes in the heart's structure; also lung disease, thyroid disease, high blood pressure, and sleep apnea |
Main diagnosis test | ECG (electrocardiogram), supported by Holter and event monitors |
Treatment | Medicines, cardioversion, and ablation procedures to block faulty signals |
Outlook | Usually not life-threatening, but needs proper treatment to prevent stroke |
What Is Atrial Fibrillation?
Atrial fibrillation, often called AFib, is a heart rhythm disorder. An irregular heart rhythm is called an arrhythmia. In AFib, the heart's upper chambers — the atria — beat chaotically and out of sync with the lower chambers, called the ventricles.
AFib can lead to blood clots in the heart. The condition also increases the risk of stroke, heart failure, and other heart-related complications. Episodes may come and go, or they may be constant.
AFib itself usually isn't life-threatening. But it is a serious condition that needs proper treatment to prevent stroke.
How a Normal Heartbeat Works
Understanding AFib starts with knowing how a healthy heart beats.
The heart has four chambers: two upper atria and two lower ventricles. Inside the upper right chamber sits a group of cells called the sinus node, which makes the signals that start each heartbeat. These signals travel across the upper chambers to the AV node, where they normally slow down, and then move to the lower chambers, causing them to squeeze and pump blood.
In a healthy heart, this process runs smoothly, and the resting heart rate is typically 60 to 100 beats a minute.
What Goes Wrong in AFib
In atrial fibrillation, the signals in the upper chambers become chaotic. The upper chambers tremble or shake instead of beating cleanly. The AV node gets flooded with signals trying to reach the lower chambers, and it cannot block them all.
The result is a fast and irregular heartbeat. In people with AFib, the heart rate may range from 100 to 175 beats a minute.
A Related Condition: Atrial Flutter
A person with atrial fibrillation may also have a related rhythm disorder called atrial flutter. The treatments for the two conditions are similar.
What are the symptoms of atrial fibrillation (AFib)?
Atrial fibrillation (AFib) can cause palpitations, chest pain, dizziness, fatigue and shortness of breath, although some people with AFib don't notice any symptoms at all.
A fast, fluttering or pounding heartbeat, called palpitations
Chest pain
Dizziness
Fatigue
Lightheadedness
Reduced ability to exercise
Shortness of breath
Weakness
Importantly, some people with AFib don't notice any symptoms at all. That is one reason regular checkups matter — AFib can be found during a health checkup done for another reason.
When to See a Doctor
If you notice symptoms of atrial fibrillation, make an appointment for a health checkup. You may be referred to a cardiologist — a doctor trained in heart diseases.
Emergency: If you have chest pain, get emergency medical help right away. Chest pain could mean that you're having a heart attack.
If AFib is found early, treatment may be easier, and it may work better.
What are the types of atrial fibrillation?
AFib is grouped into four types based on how long episodes last and whether the rhythm can be corrected.
Type | How It Behaves | What It Means for You |
Occasional (paroxysmal) | Symptoms come and go, usually lasting minutes to hours, sometimes up to a week | Symptoms may go away on their own, but some people still need treatment |
Persistent | The irregular heartbeat is constant and does not correct itself | Medical treatment is needed to reset the rhythm |
Long-standing persistent | Constant and lasts longer than 12 months | Medicines or a procedure are needed to correct the rhythm |
Permanent | The rhythm can't be reset | Medicines are needed to control the heart rate and prevent blood clots |
What causes atrial fibrillation?
The most common cause of AFib is changes in the heart's structure. Some people who have atrial fibrillation have no known heart disease or heart damage at all.
Heart Diseases and Health Conditions
Heart diseases and health conditions that can cause AFib include:
A heart condition present from birth, called a congenital heart defect
A rhythm disorder affecting the heart's natural pacemaker, called sick sinus syndrome
A sleep disorder called obstructive sleep apnea
Heart attack
Heart valve disease
High blood pressure
Lung diseases, including pneumonia
Narrowed or blocked arteries, called coronary artery disease
Thyroid disease, such as an overactive thyroid
Infections from viruses
Heart surgery, or stress due to surgery or sickness, may also cause AFib.
Lifestyle Triggers
Habits that can send the heart into AFib may include:
Drinking too much alcohol or caffeine
Illegal drug use
Smoking or using tobacco
Taking medicines that contain stimulants, including cold and allergy medicines bought without a prescription
Risk Factors
Things that can increase the risk of atrial fibrillation include:
Age — the risk of AFib increases as you grow older
Caffeine, nicotine, or illegal drug use — substances like amphetamines and cocaine make the heart beat faster and can lead to more serious irregular rhythms
Drinking too much alcohol — excess alcohol affects the heart's electrical signals
Changes in body minerals (electrolytes) — potassium, sodium, calcium, and magnesium that are too low or too high can cause irregular beats
Family history — some families carry an increased risk
Heart conditions or heart surgery — including coronary artery disease, valve disease, congenital conditions, heart attack, and prior surgery
High blood pressure — over time it can make part of the heart stiff and thick, changing how signals travel
Obesity
Other long-term health conditions — including diabetes, chronic kidney disease, lung disease, and sleep apnea
Some medicines and supplements — certain prescription drugs and cough and cold remedies
Thyroid disease — an overactive thyroid gland raises the risk
What are the complications of atrial fibrillation, including stroke risk?
A possible complication of atrial fibrillation is blood clots. Blood clots can lead to stroke.
The risk of stroke from AFib increases as you grow older. Certain health conditions also raise that risk:
High blood pressure
Diabetes
Heart failure
Some types of heart valve disease
Blood thinners are commonly used to prevent blood clots and strokes in people with atrial fibrillation. This is why following a treatment plan matters — if AFib is not well controlled, it may lead to stroke and heart failure.
How is atrial fibrillation diagnosed?
A healthcare professional diagnoses AFib by examining you, listening to your heart, and asking about your medical history and symptoms. Tests may look for conditions that change the heartbeat, such as heart disease or thyroid disease.
Tests Used to Diagnose AFib
Test | What It Does |
Electrocardiogram (ECG or EKG) | The main test for AFib; sticky sensors on the chest, arms, and legs record how the heart is beating |
Holter monitor | A small portable ECG worn for one or two days during your regular activities |
Event recorder | Records the heart only at certain times; worn up to 30 days; you press a button when symptoms occur |
Implantable loop recorder | Records the heartbeat continuously for up to three years; finds frequent or rare episodes, including after an unexplained stroke |
Echocardiogram | Sound waves create images of the beating heart and show blood flow through the heart and valves |
Exercise stress test | Walk on a treadmill or pedal a bike while the heart is checked; medicine may substitute if you cannot exercise |
Blood tests | Look for conditions or substances that may affect the heart |
Chest X-ray | Shows the condition of the lungs and heart |
What are the treatment options for atrial fibrillation?
The goals of AFib treatment are to reset and control the heartbeat and to prevent blood clots. Your treatment plan depends on how long you've had AFib, your symptoms, and the cause of the irregular heartbeat. Together, you and your healthcare team choose the best option — and it's important to follow the plan.
Medicines
Medicines may control the speed of the heartbeat, reset the rhythm, or prevent blood clots:
Beta blockers — help slow the heart rate
Calcium channel blockers — control the heart rate (may need to be avoided if you have heart failure or low blood pressure)
Digoxin (Lanoxin) — controls the heart rate at rest, but not as well during activity; most people need additional medicines
Anti-arrhythmics — control the rate and rhythm but have more side effects, so they are used sparingly
Blood thinners (anticoagulants) — prevent blood clots and reduce stroke risk; examples include warfarin (Jantoven), apixaban (Eliquis), dabigatran (Pradaxa), edoxaban (Savaysa), and rivaroxaban (Xarelto). Warfarin requires regular blood tests to check its effects.
Cardioversion
If symptoms are bothersome, or if this is your first AFib episode, a treatment called cardioversion may be done to reset the heart rhythm:
Electrical cardioversion — electric shocks are sent to the heart through paddles or patches placed on the chest.
Drug cardioversion — medicines given through a vein or by mouth reset the rhythm.
Cardioversion is usually a scheduled hospital treatment but may be done in emergencies. Before a scheduled treatment, you may be told to take a blood thinner such as warfarin for a few weeks to reduce the risk of clots and strokes.
After electrical cardioversion, rhythm-control medicines may be needed for life to prevent AFib from returning — and even with medicine, AFib could come back.
Cardiac Ablation
If AFib doesn't improve with medicine, a procedure called cardiac ablation may be necessary. Sometimes it is the first treatment instead.
During cardiac ablation, a doctor guides a flexible tube called a catheter through a blood vessel, usually in the groin, to the heart. Sensors at the catheter tip use heat or cold energy to create tiny scars. Heart signals can't pass through the scars, so the procedure blocks the faulty signals that cause AFib. More than one catheter may be used. Less commonly, ablation is done with a scalpel during open-heart surgery.
Types of ablation include:
Atrioventricular (AV) node ablation — heat energy destroys the connection between the upper and lower chambers; a pacemaker is needed for life afterward
Maze procedure — a pattern of scar tissue in the upper chambers blocks stray signals; the surgical maze version uses open-heart surgery and is preferred when you're already having another heart operation, such as bypass surgery or valve repair
Hybrid atrial fibrillation ablation — combines ablation with surgery, used for long-standing persistent AFib
Pulsed field ablation — uses high-energy electric pulses instead of heat or cold to create the scar areas
AFib may return after cardiac ablation. If this happens, another ablation or treatment may be recommended. Blood thinners may be needed for life afterward to prevent strokes.
Left Atrial Appendage Closure
If you have AFib but can't take blood thinners, a doctor may close the left atrial appendage — a small sac in the left upper chamber where most AFib-related clots form. A closure device is guided in through a catheter and stays in permanently. This procedure is also an option for some people who are already having another heart surgery.
How can you lower your risk of atrial fibrillation with heart-healthy habits?
A healthy lifestyle can lower the risk of heart disease and may help prevent atrial fibrillation (AFib) through habits such as healthy eating, regular exercise and not smoking. Heart-healthy steps include:
Eat healthy foods — plenty of fruits, vegetables, and whole grains; limit sugar, salt, and saturated fats.
Exercise and stay active — 30 to 60 minutes of physical activity most days of the week, unless your healthcare team says otherwise.
Don't smoke or use tobacco.
Keep a healthy weight.
Control blood pressure — get it checked at least every two years if you're 18 or older, and more often if you're over 40 or have risk factors.
Get your cholesterol checked — ask how often you need the test; lifestyle changes and medicines may help.
Limit alcohol — binge drinking (five drinks in two hours for men, four for women) raises AFib risk, and even smaller amounts can trigger AFib in some people.
Practice good sleep habits — adults should aim for 7 to 9 hours a night.
Manage stress.
Regular health checkups matter too. Tell your healthcare team if your AFib symptoms get worse.
Frequently Asked Questions
What is atrial fibrillation (AFib)?
Atrial fibrillation is an irregular and often rapid heart rhythm caused by chaotic electrical signals in the heart's upper chambers. It is a type of arrhythmia that can lead to blood clots and increases the risk of stroke and heart failure.
What does atrial fibrillation feel like?
Many people feel a fast, fluttering, or pounding heartbeat called palpitations. Other common symptoms include shortness of breath, dizziness, lightheadedness, fatigue, weakness, chest pain, and reduced ability to exercise. Some people notice no symptoms at all.
Is atrial fibrillation dangerous?
AFib itself usually isn't life-threatening, but it is a serious condition because it can cause blood clots that lead to stroke, and it raises the risk of heart failure. Proper treatment is needed to prevent these complications.
What causes atrial fibrillation?
The most common cause is changes in the heart's structure. Other causes include high blood pressure, heart valve disease, heart attack, thyroid disease, lung disease, and sleep apnea. Lifestyle factors such as excess alcohol, too much caffeine, smoking, and stimulant medicines can also trigger episodes.
How is atrial fibrillation diagnosed?
The main test is an ECG (electrocardiogram), which records the heart's electrical activity. Doctors may also use a Holter monitor, an event recorder, an implantable loop recorder, an echocardiogram, exercise stress tests, blood tests, or a chest X-ray.
What is the best treatment for atrial fibrillation?
Treatment depends on how long you've had AFib, your symptoms, and its cause. Options include medicines (to slow the heart rate, reset the rhythm, or prevent clots), cardioversion to shock the heart back to a normal rhythm, and ablation procedures that block faulty electrical signals.
Conclusion: What to Remember About Atrial Fibrillation
Atrial fibrillation is an irregular, often rapid heartbeat driven by chaotic electrical signals — and while it usually isn't life-threatening on its own, it carries a real risk of blood clots and stroke that makes proper treatment essential. The most important lessons from this guide are:
Know the warning signs. A fast, pounding heartbeat, shortness of breath, and dizziness deserve a checkup — and remember that some people feel nothing at all, which makes regular screenings valuable.
Follow your treatment plan. Medicines, cardioversion, and ablation can reset and control the rhythm and block faulty signals; poorly controlled AFib raises the risk of stroke and heart failure.
Your habits matter. Blood pressure control, exercise, healthy eating, limited alcohol, no smoking, and good sleep all lower your risk of AFib and heart disease.
This guide gives you one clear, plain-language place to understand AFib from start to finish. If you've noticed an irregular or pounding heartbeat, the best next step is to make an appointment for a health checkup — early detection makes treatment easier and more effective.
Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
References
Mayo Clinic. Atrial fibrillation — Symptoms & causes. Accessed October 12, 2026. https://www.mayoclinic.org/diseases-conditions/atrial-fibrillation/symptoms-causes/syc-20350624
Mayo Clinic. Atrial fibrillation — Diagnosis & treatment. Accessed October 12, 2026. https://www.mayoclinic.org/diseases-conditions/atrial-fibrillation/diagnosis-treatment/drc-20350630
Voskoboinik A, Kalman JM, De Silva A, et al. Alcohol abstinence in drinkers with atrial fibrillation. N Engl J Med. 2020;382(1):20-28. PMID 31893513. https://doi.org/10.1056/NEJMoa1817591
Cui Y, Yao J, Zhang J, et al. Catheter ablation for atrial fibrillation in patients with left ventricular ejection fraction ≤ 45%: a meta-analysis of randomized controlled trials. Arq Bras Cardiol. 2024;121(1):e20230214. PMID 38422349. https://doi.org/10.36660/abc.20230214
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