Atrial fibrillation (AFib) is a condition that causes your heart to beat in an irregular rhythm. One way to classify AFib is by what’s causing it. Valvular AFib and nonvalvular AFib are terms used to describe AFib caused by two different factors.

AFib is considered valvular when it’s seen in people who have a heart valve disorder or a prosthetic heart valve. Nonvalvular AFib generally refers to AFib caused by other things, such as high blood pressure or stress.

There’s still some debate over how exactly to define valvular AFib. Anywhere from 4 to 30 percent of people with AFib are thought to have valvular AFib. The wide range may be due to the lack of consensus about which causes should be counted as valvular.

Your doctor will consider which type of AFib you have before prescribing treatments. Nonvalvular and valvular AFib are often treated differently.

It’s possible to have AFib and experience no symptoms. You can have the condition for years and not realize it until you go for a physical exam and have an electrocardiogram (EKG). If you do experience AFib symptoms, they may include:

  • chest pain
  • confusion
  • dizziness
  • fatigue
  • heart palpitations, which can make you as if your heart is flip-flopping or racing
  • lightheadedness
  • shortness of breath
  • unexplained weakness

It’s possible for you to go in and out of AFib. This is known as paroxysmal AFib. If you have AFib for longer than 12 months, it’s known as long-standing persistent AFib.

A standard definition of valvular AFib doesn’t yet exist. However, there are some generally accepted causes of valvular AFib:

Mitral valve stenosis

In mitral valve stenosis, the mitral valve is narrower in size than normal. The mitral valve connects the left atrium of your heart to the left ventricle. As a result of this condition, blood doesn’t flow normally into the left ventricle. This results in an irregular heartbeat.

Rheumatic fever is the most common cause of mitral valve stenosis. While this condition isn’t very common in the United States anymore, rheumatic fever still occurs in developing countries.

Artificial heart valve

Another cause of valvular AFib is having an artificial heart valve. Artificial heart valves are used to replace a diseased or scarred heart valve. The valves can be made from different materials, including:

  • a mechanical heart valve
  • a tissue valve from an animal donor
  • a tissue valve from a human donor

If you don’t have any symptoms of AFib, your doctor may find the irregular heart rhythm when you’re being tested for an unrelated condition. If your doctor thinks you may have AFib, they’ll do a physical examination and ask about your family and medical history. They’ll also ask you to do further testing.

In addition to an EKG, other tests for AFib include:

Your doctor may use several different treatments to prevent blood clots and control your heart rate and rhythm.

Preventing blood clots

Anticoagulation medication helps reduce the likelihood of blood clots. This medication is important if you have an artificial heart valve. This is because blood clots can form on the leaflets or flaps of the artificial valve.

The most common anticoagulants are vitamin K antagonists, such as warfarin (Coumadin). These anticoagulants block your body’s ability to use vitamin K, which is needed to create a clot.

Newer anticoagulants, known as non-vitamin K oral anticoagulants (NOACs), have also emerged on the market. These include rivaroxaban (Xarelto), dabigatran (Pradaxa), apixaban (Eliquis), and edoxaban (Savaysa). However, these newer anticoagulants aren’t recommended for people with valvular AFib, especially those with mechanical heart valves.

According to a 2013 study on people with mechanical heart valves, participants who took dabigatran were more likely to experience episodes of bleeding and blood clotting than those who took warfarin. The researchers stopped the study early because of the increased incidence of blood clotting in people who took the newer anticoagulants.

Controlling heart rate and rhythm

Your doctor may use a procedure known as cardioversion to reset your heart’s rhythm. This involves delivering an electric shock to your heart to restart its electrical activity.

Certain medications can also help maintain your heart’s rhythm. Examples include:

More invasive procedures, such as a catheter ablation, are also available to restore the heart’s rhythm. Before recommending ablation, your doctor will consider your overall health and whether anticoagulants have worked for you.

Having mitral valve stenosis or a mechanical heart valve increases your risk for blood clotting. Having AFib increases this risk even further. People with valvular AFib are more likely to have a blood clot than people who have nonvalvular heart disease.

If you do have valvular AFib, treatment with anticoagulants and other interventions to control heart rate can help to reduce your risk for heart attack and stroke.