What is Atrial Fibrillation (AFib)?
Last Updated
Aug 2, 2025
Atrial fibrillation (AFib) is the most common type of irregular heartbeat. It affects about 52 million people worldwide. As people live longer, tests improve, and risk factors such as age and high blood pressure become more common, that number is expected to rise.
With the right treatment plan and support, people with AFib can continue to lead active, healthy lives.
Understanding AFib in Simple Terms
The heart has four chambers—two atria (upper) and two ventricles (lower). The atria collect blood coming into the heart, and the ventricles pump blood back out to the body and lungs. Normally, these chambers work in sync, guided by the heart’s electrical system.
The heartbeat starts in the sinoatrial (SA) node, the heart’s natural pacemaker. Signals travel through the atria, causing them to contract and push blood into the ventricles. The signal then moves through the atrioventricular (AV) node and into the ventricles, which contract to pump blood to the rest of the body. This cycle repeats about 60–100 times per minute at rest, keeping blood moving smoothly.
In atrial fibrillation (AFib), these electrical signals become irregular and chaotic. The atria beat out of sync with the ventricles and may not pump blood forward effectively. As a result, blood can sometimes pool in the atria and form clots. The heart may also beat much faster—often 100 to 175 times per minute—putting extra strain on the heart muscle. Over time, this irregular rhythm can raise the risk of complications such as stroke or heart failure.
What Does Afib Feel Like?
AFib can feel different for everyone. Symptoms can include:
Racing, fluttering, pounding, or flip-flopping heartbeat
Feeling unusually tired or weak
Shortness of breath, especially during activity
Dizziness, lightheadedness, confusion, or chest discomfort
Some people don’t notice any symptoms at all and only learn they have AFib during a routine exam, which is why follow-up and regular monitoring are so important.
Types of Afib
Understanding your type of afib helps you and your healthcare team create the best treatment plan. AFib is classified into types based on how long the irregular rhythm lasts and whether it stops on its own.
Type | How long it lasts | Key details |
|---|---|---|
Paroxysmal AFib | Less than 7 days (often <24 hours) | Starts and stops on its own. Episodes may come and go, and can become more frequent over time. |
Persistent AFib | More than 7 days | Does not stop on its own. Usually requires treatment to restore normal rhythm. |
Long-standing Persistent AFib | Continuous for more than 12 months | Still considered potentially reversible. Your care team may try to restore normal rhythm. |
Permanent AFib | Continuous, long-term | A decision has been made not to try restoring normal rhythm. Focus shifts to rate control and preventing complications. |
Why Afib Matters: Understanding Your Risks
AFib itself usually isn’t life-threatening, but it raises the risk of blood clots, stroke, and other heart problems if it isn’t managed.
Stroke Risk
When the atria beat steadily, they push blood smoothly through the heart. In AFib, that steady rhythm is disrupted, so blood can pool in the atria instead of moving forward properly. If a clot forms there and travels to the brain, it can cause a stroke. People with AFib are about 5 times more likely to have a stroke than those without it. With proper treatment, the risk of stroke can be greatly reduced.
Other Heart-Related Complications
Heart failure: The heart may weaken from working too hard when blood isn’t pumped out effectively.
Other rhythm problems: AFib can make the heart more prone to other irregular rhythms, such as atrial flutter.
Cardiomyopathy: A long-term rapid heart rate can weaken the heart muscle.
What Causes AFib?
Sometimes AFib develops without a clear cause. In many cases, though, certain health conditions, lifestyle factors, or family traits raise the chances of developing it. Managing these risk factors can help control symptoms and reduce complications.
Heart-Related Causes
High blood pressure (most common)
Heart valve problems
Coronary artery disease
Previous heart attack or heart surgery
Congenital heart defects
Other Health Conditions
Overactive thyroid (hyperthyroidism)
Sleep apnea
Diabetes
Chronic kidney disease
Lung diseases
Lifestyle Factors
Excessive alcohol ("holiday heart syndrome")
Extreme stress or fatigue
Caffeine (in sensitive individuals)
Certain medications or stimulants
Risk Factors You Can't Change
Age: Risk increases as you get older
Family history: Genetics play a role
Gender: More common in men, though women have higher stroke risk
How is AFib Diagnosed?
AFib is usually diagnosed by reviewing your medical history, doing a physical exam, and using tests that check your heart rhythm and function.
Tests and Tools
Electrocardiogram (ECG or EKG): Quick, painless test that records your heart’s electrical activity. It’s the most common way to detect an irregular rhythm.
Holter monitor: Worn for 24–48 hours to track your heart’s rhythm over time and catch episodes of AFib.
Event monitor: Worn for up to 30 days to record irregular rhythms that may not appear during a standard ECG.
Echocardiogram: Uses ultrasound to create images of the heart’s structure and function. Helps identify blood clots, valve problems, or other heart changes.
Blood tests: Check for conditions such as thyroid disease, kidney problems, or other health issues that may contribute to AFib.
What to Expect During Diagnosis
Medical history: Your clinician will ask about your symptoms, family history, and risk factors such as high blood pressure or heart disease.
Physical exam: Your clinician will listen to your heart for signs of an irregular rhythm.
Symptom discussion: Be prepared to talk about symptoms such as shortness of breath, chest discomfort, or fatigue.
Testing plan: Your clinician will review which tests are needed, explain how they guide care, and work with you on next steps.
By working closely with your healthcare team and following your personalized treatment plan, you can take important steps to prevent blood clots and manage your AFib effectively.
Treatment Options for Afib
Treatment for Afib focuses on lowering the risk of stroke, managing symptoms, and protecting heart health. The best plan depends on your type of AFib, your overall health, and your preferences.
Addressing Causes and Risk Factors
Managing other health conditions—such as high blood pressure, sleep apnea, or thyroid problems—can help reduce AFib episodes. Lifestyle changes also play a role. Reaching a healthy weight, controlling diabetes, and limiting alcohol use can all support better heart health.
Preventing Stroke
Blood thinners (anticoagulants) are often recommended because they lower stroke risk in people with AFib. In most cases, anticoagulants are preferred over aspirin for preventing stroke in AFib. Aspirin alone offers limited protection and carries a bleeding risk.
Rate Control
Rate control involves using medicines to slow the heartbeat, giving the heart more time to fill with blood before each contraction. The goal isn’t to get rid of AFib but to keep the rate at a safer level, which helps reduce symptoms and strain on the heart.
Rhythm Control
Rhythm control involves medicines that try to restore a normal heartbeat. The goal is to reduce symptoms and improve quality of life, especially for people who still feel unwell even when their heart rate is controlled.
Procedures and Devices
Some people may need procedures or devices as part of their AFib treatment. These can include electrical cardioversion, catheter ablation, or surgical options to restore normal rhythm. For people who cannot take long-term blood thinners, devices that close off the left atrial appendage may help reduce stroke risk.
Taking Control: Your Next Steps
Work With Your Care Team
Managing AFib usually involves a team approach. Your care team may include:
Your primary care clinician
A cardiologist (heart specialist)
An electrophysiologist (heart rhythm specialist)
These clinicians play a key role in monitoring your condition, managing risks, and guiding treatment decisions.
Key Questions for Your Care Team
Bringing questions to your appointments can help you feel more confident and involved in your care. Consider asking:
What type of AFib do I have?
What's causing my AFib?
What's my stroke risk?
What are my treatment options?
How will AFib affect my daily life?
What symptoms should prompt me to seek emergency medical attention?
When to Call 911?
Call 911 right away if you experience:
Chest pain or pressure
Severe shortness of breath
Signs of stroke (F.A.S.T.):
Face: Drooping on one side
Arm: Weakness or numbness
Speech: Slurred or hard to understand
Time: Call 911 immediately
Living Well with AFib
An AFib diagnosis doesn’t mean you can’t keep doing the things you enjoy. Many people with AFib continue to travel, exercise, work, and spend time with loved ones. With the right treatment plan and support, living well with AFib is possible.
Taking the First Step
Learning about your condition is an important part of managing it. By understanding AFib and working closely with your care team, you can take an active role in protecting your health and quality of life.
References
American Heart Association. How is AFib diagnosed? Updated June 30, 2023. Accessed September 27, 2025. https://www.heart.org/en/health-topics/atrial-fibrillation/treatment-and-prevention-of-atrial-fibrillation/afib-diagnosis
American Stroke Association. Stroke symptoms. Updated May 1, 2024. Accessed September 27, 2025. https://www.stroke.org/en/about-stroke/stroke-symptoms
Heart & Stroke Foundation of Canada. Atrial fibrillation. Updated February 2024. Accessed September 27, 2025. https://www.heartandstroke.ca/heart-disease/conditions/atrial-fibrillation
Joglar JA, Chung MK, Armbruster AL, et al. 2023 ACC/AHA/ACCP/HRS guideline for the diagnosis and management of atrial fibrillation: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2023;149(1):e1-e150. doi:10.1161/CIR.0000000000001193
MedlinePlus. Atrial fibrillation. National Library of Medicine. Updated July 10, 2024. Accessed September 27, 2025. https://medlineplus.gov/atrialfibrillation.html
National Heart, Lung, and Blood Institute. Causes and risk factors of atrial fibrillation. National Institutes of Health. Updated March 24, 2022. Accessed September 27, 2025. https://www.nhlbi.nih.gov/health/atrial-fibrillation/cau
National Heart, Lung, and Blood Institute. Types of atrial fibrillation. National Institutes of Health. Updated March 24, 2022. Accessed September 27, 2025. https://www.nhlbi.nih.gov/health/atrial-fibrillation/types
