What is atrial fibrillation (AFib)?

Atrial fibrillation (AFib) is the most common type of abnormal heart rhythm (arrhythmia). Normally, a group of cells in the right upper heart chamber (atrium) gives the signal to start your heartbeat. These cells are called the sinoatrial (SA) node. The signal quickly travels down the heart’s conducting system. From the right atria, the signal travels to the upper-left filling chamber of the heart (left atrium). From there, it passes through another node of tissues called the AV node. Then it reaches the left and right ventricle. These are the two lower pumping chambers of the heart. As the signal travels, it triggers the chambers of the heart to contract. The atria contract with each heartbeat. This moves blood into the ventricles. Then the ventricles contract to move blood out to the rest of the body.

During AFib, the heart gets electrical signals that come from outside the SA node. This makes the atria contract in a disorganized way. It causes the atria to quiver (fibrillate). The jumbled signals are then sent to the ventricles. It makes them contract irregularly and often quickly. The atria and the ventricles no longer contract with each other in the right rhythm. The amount of blood pumped out to the body will vary with each heartbeat. The ventricles may not be able to pump blood well enough to the body.

The quivering atria can lead to blood pooling in the heart. That's because the blood doesn't move as well as it should from chamber to chamber. Pooling can cause blood clots to form inside the heart. Most clots form inside the left atrium. That's because the left atrium has a pouch in the muscle wall called the left atrial appendage. It's often large with several lobes. Experts don't fully know the purpose of this pouch. Some think it might be like a pressure relief chamber for the left atrium. But during AFib, blood can pool inside the lobes. This raises the risk of blood clots. The clots can then be pumped out of the heart and travel to the brain. This can cause a stroke. That's why AFib makes the risk for stroke much higher. So people with AFib may take medicines to thin their blood. This lowers the risk.

Normal heart.

Atrial fibrillation.

There are 3 types of AFib:

• Paroxysmal. This AFib occurs once in a while. Then it goes away on its own. It may last for seconds, minutes, hours, or up to 7 days. Then it goes back to a normal rhythm.

• Persistent. This AFib doesn't go away on its own. Treatment is needed to return the heart to its normal rhythm. It lasts for 7 days or longer. AFib that lasts longer than a year is called long-standing persistent AFib. If it's not treated, this AFib will become permanent.

• Permanent. AFib may be permanent when a decision is made to stop trying to control the heart’s rhythm. Or sometimes a normal rhythm can't be restored, even with treatment.

The risk of having AFib goes up with age. It's more common in men than in women.

What causes AFib?

AFib can be caused by any problem that changes the way the heart handles its electrical signals. Sometimes the cause isn't known. There are several things that can raise this risk. Some of them include:

• Older age.

• High blood pressure.

• Coronary artery disease.

• Heart failure.

• Rheumatic heart disease from a past Streptococcus infection.

• Heart valve defects, such as mitral valve prolapse with regurgitation.

• Pericarditis.

• Heart defects that you have at birth (congenital).

• Hyperthyroidism.

• Obesity.

• Diabetes.

• Lung disease.

• Obstructive sleep apnea.

• Metabolic syndrome.

• High-dose steroid therapy.

• Cardiac surgery.

AFib is also more likely to happen during an infection or soon after surgery. Stress or alcohol may also set off attacks. People who do a lot of long endurance exercises can get Fib. An example is running marathons.

Certain people may be at greater risk of getting AFib. This is because of mutated, or changed, genes they inherited from their parents. Experts don't yet fully understand this.

Who is at risk for AFib?

AFib is more common in people who are older than 65. It’s also more common in men than women. Heart disease, high blood pressure, and thyroid problems put people at risk for AFib. So do too much alcohol use, sleep apnea, and some lung diseases.

What are the symptoms of AFib?

AFib can cause different symptoms. This is especially true when it's not treated. For instance, you may:

• Feel that your heart skips beats or beats too hard. (These are called heart palpitations.)

• Feel short of breath.

• Have chest pain.

• Feel dizzy or faint.

• Feel weak and tired (fatigue).

Sometimes AFib has no symptoms. The first sign may be symptoms of a stroke.

How is AFib diagnosed?

You will be asked about your past health and will get a physical exam. An internist or primary care doctor will often make the diagnosis. You might see a cardiologist for more assessment and treatment.

An electrocardiogram (ECG) is used to help diagnose AFib. Doctors use this test to study the heart signal and rhythm. In some cases, the diagnosis can be made based on this test alone. If your symptoms come and go, you might need to wear an ECG Holter monitor or event recorder for 24 to 48 hours or more. Some monitors can be worn for up to a month. They measure and record your ECG as you do your daily activities. This lets your health care provider check your heart's activity over time. If your symptoms don't happen often, you may get a small implantable heart recording device called a loop recorder. It's put under the skin just over the heart. It can check for arrhythmias over several years. A wearable device, like a smartwatch, might be used to watch for AFib and record an ECG signal.

Other tests can help plan treatment. These include:

• Echocardiogram. This checks the heart's structure and function.

• Cardiac stress testing. This checks the blood flow in the heart.

• Blood tests. These check for thyroid levels, diabetes, and other health problems.

• Sleep study. This is done when obstructive sleep apnea is suspected.

How is AFib treated?

Your health care team will work with you to make a treatment plan. Treatment options vary based on your health history, symptoms, and preferences. Some people who don’t have any symptoms may not need much treatment.

Here are some ways AFib may be treated.

What are possible complications of AFib?

Stroke and heart failure are the major problems caused by AFib. Blood can pool in the atria during AFib. This can cause a clot. The clot can travel to the brain and block a vessel there. This can cause a stroke. Medicines that thin the blood help reduce this risk. Whether you take them will depend on your risk for stroke. If you're at low risk, you may not need to take anything at all. If you are at high risk, you'll need a blood thinner.

AFib also sometimes causes heart failure. Because the chambers of the heart are beating so irregularly, they can’t fill or squeeze normally. This is especially true if the heart is beating very fast. Over time, this can weaken the heart. And it can prevent the heart from pumping enough blood to the body. Heart failure is treated with lifestyle changes, medicine, procedures, or surgery. Medicines that lower the heart rate will also help prevent heart failure.

AFib is also linked to a raised risk for dementia and a shorter lifespan.

What can I do to prevent AFib?

Controlling risk factors may prevent AFib. This includes managing;

• Heart disease.

• High blood pressure.

• Thyroid problems.

• Sleep apnea.

• Obesity.

• Lung diseases.

Making healthy lifestyle choices can also help you manage things that might put you at risk. For example:

• Eat healthy food.

• Get regular exercise.

• Stay at a weight that's healthy for you.

• Avoid smoking.

• Drink alcohol in moderation, if at all. If you have a problem with alcohol use, consider getting help.

How can I manage AFib?

You'll need to have regular follow-up visits for AFib. Your doctor may prescribe blood thinners called direct-acting oral anticoagulants. They help prevent a stroke. You don't need frequent blood tests for these medicines. But you may need to have your kidney function checked routinely.

If you take warfarin, you'll need more frequent blood tests, such as a prothrombin time (PT). This test measures the time it takes for your blood to clot. It records your reading as an international normalized ratio (INR). Your INR can change over time. It's based on things like the food you eat or medicines you take. Your INR needs to be kept at a certain level to protect you from clotting. Your doctor can change your medicine dose if needed to keep you at a safe level.

Your doctor may advise using a device called a left atrial appendage closure. It's used to prevent stroke if you can't take blood thinners or have a high risk of bleeding. It closes off the left atrial appendage in the left atrium. This is where most blood clots form that cause a stroke.

There are other steps you can take to help you manage your AFib and maintain a healthy lifestyle. 

• Eat about the same amount of certain foods, such as leafy green vegetables, if you're taking warfarin.

• Eat a heart-healthy diet.

• Don't smoke.

• Be physically active, and stay at a weight that's healthy for you.

• Keep your cholesterol at healthy levels with lifestyle and medicine.

• Don't use alcohol. It can trigger heart rhythm problems.

• Make sure your health care providers know about all the over-the-counter medicines you use.

• Make sure all your doctors, dentists, and pharmacists know if you are taking a medicine to prevent blood clots.

• If you miss a dose of a blood-thinning medicine, don't double up your dose. Ask your provider what you should do.

When should I call for help?

Get emergency medical care if you have severe symptoms like chest pain or sudden shortness of breath. Also get help if you have signs of severe bleeding.

See your health care provider soon if your symptoms are gradually getting worse, or if you have any new mild symptoms or side effects.

Key points about AFib

• AFib is the most common abnormal heart rhythm. The atria quiver instead of contracting the way they should. The heart rate usually increases. It's a serious condition. But most people with AFib can lead normal, active lives. You will need to be checked on a regular basis.

• Follow all of your health care team’s instructions about medicines, lifestyle, and monitoring.

• You may get medicine to control your heart rate or rhythm.

• Procedures like catheter ablation or even surgery can help prevent AFib.

• You may need blood thinners to help prevent a stroke.

• Depending on what blood thinner you take, you may need frequent blood tests and monitoring.

• Go to all of your health care appointments.

Next steps

Here are some tips to help you get the most from a visit to your health care provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis. Note any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you don't take the medicine or have the test or procedure.

• If you have a follow-up visit, write down its date, time, and purpose.

• Know how you can contact your provider if you have questions.