Silent atrial fibrillation occurs when the heart’s chambers beat irregularly. It does not cause symptoms, and people may only become aware of it through medical testing and physical examinations.

Atrial fibrillation (AFib) is a type of arrhythmia, which refers to an irregular heartbeat. Silent AFib is an asymptomatic type of AFib, meaning it involves no symptoms.

With silent AFib, people do not experience the symptoms characteristic of AFib, such as heart palpitations or breathing difficulties. Individuals may also refer to silent AFib as subclinical asymptomatic AFib.

This article explains the possible warning signs, causes, risk factors, diagnosis, treatment, and outlook for silent AFib.

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Silent AFib does not cause symptoms, so people may not have any warning signs of the condition. Around one-third of those with AFib may not experience symptoms.

Doctors may detect AFib only through a physical examination or routine testing.

People with symptomatic Afib may experience the following:

Symptoms of AFib may only be occasional or more frequent and obvious. People with heart disease are more likely to be aware of AFib symptoms.

Learn more about AFib.

AFib, with or without symptoms, occurs due to changes in the electrical activity or tissues of the heart.

With a regular heartbeat, the electrical signal causing the heartbeat begins in the atria, which are the upper chambers of the heart.

The electrical signal causes the upper chambers to contract, which pumps blood to the ventricles, which are the lower chambers of the heart. As the electrical signal travels through the heart, it causes the ventricles to contract and pump blood away from the heart.

With AFib, the heart has irregular electrical signals, which interrupt the body’s typical heartbeat. This causes the heart’s atria to contract atypically, and the upper and lower chambers become uncoordinated from each other.

The heartbeat becomes too fast and irregular, and the heart cannot work as effectively to pump blood.

Changes to the heart’s structure or a lack of blood flow to the heart can cause AFib. Genetic issues, heart disease, and inflammation can all affect the tissue of the heart and alter the regular rhythm.

According to a 2021 study, risk factors for silent AFib include:

Other factors that increase the risk of AFib include:

People with heart disease are more likely to experience symptoms of AFib than those without it. If heart disease worsens, symptoms may also become more noticeable.

Since silent AFib does not cause noticeable symptoms, a doctor may identify silent AFib through testing for another reason.

Certain wearable devices can detect silent AFib. Smartphones and watches, such as the Apple Watch and Fitbit, use photoplethysmography, a technology that can measure heart rhythm and identify AFib. Cardiac implant devices, such as pacemakers and defibrillators, can also detect silent AFib.

Doctors may also use a Holter monitor, which is a portable device that records the heart’s electrical activity over a certain period.

Doctors also use an electrocardiogram to make an AFib diagnosis. An ECG test records the heart’s electrical activity and shows whether the heartbeat is regular or irregular.

If a doctor identifies silent AFib, they may prescribe treatment to help treat the heart’s irregular rhythm or slow the heart rate. This may include medications such as:

People with silent AFib may have cardioversion, which uses an electric shock to restore the typical electrical signaling of the heart.

Lifestyle choices to manage risk factors are also important to prevent AFib from worsening. They include:

Without diagnosis and treatment, AFib can cause serious complications. People who are Black or African American may be at an increased risk of AFib complications compared to white individuals. Complications of AFib can include:

  • Blood clots: When the heart cannot pump blood effectively, blood may pool in the heart, forming blood clots.
  • Dementia: AFib may reduce blood flow reaching the brain or block blood vessels in the brain, causing dementia.
  • Stroke: A stroke may occur if a blood clot breaks free and blocks a blood vessel to the brain.
  • Heart failure: Heart failure may occur due to changes in how the heart beats and pumps blood.

In rare cases, having a serious heart condition alongside AFib may increase the risk of cardiac arrest, where the heart suddenly stops.

Learn more about the effects of AFib.

People must contact a doctor if they notice symptoms of AFib, even if they occur occasionally or are mild.

Tracking any symptoms, including when they occur and if they change, may help a doctor diagnose AFib or other heart conditions.

Undetected AFib can lead to serious complications, which can sometimes be the first indication a person has AFib. People will need to seek immediate medical attention or call 911 if they experience any of the following symptoms:

  • chest pain, such as a feeling of increased pressure or squeezing, which may go and come back
  • pain or discomfort in the upper body, including the jaw, neck, shoulders, back, arms, or stomach
  • shortness of breath
  • nausea
  • feeling lightheaded
  • breaking out in a cold sweat
  • drooping in the face
  • weakness in an arm
  • slurred speech or difficulty speaking

Learn about the FAST symptoms of a stroke.

According to a 2022 study, AFib may reduce a person’s life expectancy by an average of 2 years. The research examined trends in AFib and mortality across 45 years.

According to the Centers for Disease Control and Prevention (CDC), AFib contributes to around 158,000 deaths in the United States annually.

Treatment, regular monitoring, and lifestyle changes can help people manage AFib and prevent repeat episodes or complications.

Silent AFib does not cause symptoms. Certain wearable devices and medical testing can help detect it, but doctors often diagnose it when treating someone for a complication of AFib.

Getting a prompt diagnosis and treatment for AFib is essential to help prevent complications. Lifestyle changes, medications, and sometimes surgery can treat and manage the condition.