Silent atrial fibrillation (AFib) is the same as other types of AFib except that you don’t know it’s there. You might not have any symptoms.

AFib is the most common cardiac arrhythmia, affecting up to 3.2% of people worldwide. This abnormal heart rhythm is an error in the heart’s electrical system. It causes quivering of the atrium, which is a chamber in the heart.

Many people with AFib get a diagnosis after having symptoms like heart palpitations, chest pain, or dizziness. But not everyone with AFib has symptoms. Silent AFib can develop without noticeable symptoms, which may make it even more dangerous.

This article will review the differences between silent and traditional AFib, as well as what this diagnosis can mean for your overall health.

Silent AFib is essentially the same condition as AFib but without noticeable symptoms that can alert you to a problem. Silent AFib is also known as subclinical asymptomatic AFib.

Like AFib, silent AFib is due to a lack of coordination between the four chambers of the heart — or, more specifically, the top two chambers (atria) on each side of the heart. Blood collects in each atria before moving to the lower chambers of the heart (ventricles), where blood is pumped out to the body or to the lungs.

A problem with the conduction of electrical impulses through the heart is a common cause of AFib.

The result is a quivering of the atria that leads to the inefficient movement of blood to the ventricles. This stagnation of blood in the atria can reduce the flow of blood through the circulatory system and make blood clots more likely to form.

Some common symptoms reported with AFib include:

  • heart palpitations or a racing heart
  • chest pain
  • fatigue
  • dizziness
  • weakness
  • sweating
  • changes in the regularity of your heartbeat

Learn more about the symptoms of AFib here.

These symptoms can be uncomfortable and unsettling, but they’re your body’s way of alerting you to a problem. With silent AFib, these symptoms usually don’t appear or aren’t noticed, so AFib goes untreated.

In one study of a group of people over 65 years old, about 23% were found to have AFib. For 40% of those people, the AFib didn’t cause any symptoms.

Doctors diagnose AFib with an electrocardiogram (ECG). An ECG is a visual interpretation of your heart’s rhythm. This noninvasive test uses electrodes to detect signals from your heart and translate their patterns onto paper.

Your symptoms or the presence of an irregular pulse may raise suspicions, but your healthcare team cannot confirm a diagnosis without an ECG.

In AFib, silent or otherwise, an ECG will reveal an irregular heart rhythm that lacks a P-wave. This is what signals the movement of blood from the atria to the ventricles with each heartbeat.

While you may have an ECG to help diagnose the cause of particular symptoms, doctors usually diagnose silent AFib incidentally — or by accident — when they do an ECG for another purpose, such as pre-operative testing.

All types of AFib can have consequences. Over time, the condition can weaken the heart and increase your chance of developing dangerous blood clots. Untreated or uncontrolled AFib can cause complications including:

  • heart failure
  • heart attack
  • stroke
  • systemic embolism
  • death

With an early diagnosis, doctors can treat AFib in hopes of preventing these complications. With silent AFib, however, outcomes are usually worse because the condition itself never causes symptoms and the irregular heartbeat is never treated.

Paroxysmal AFib is a sudden bout of AFib that usually begins and ends suddenly, with or without significant symptoms.

This type of AFib can occur more than once, but doctors don’t really consider it a permanent condition.

Silent AFib, on the other hand, is usually permanent but unnoticed.

Many cases of silent AFib progress to severe events, so treatments are emergent and will depend on what specific complication you experience. For example, if you develop a stroke or heart attack, your healthcare team will work to clear the blockage in blood flow to prevent long-term damage.

If a doctor finds that you have silent AFib before a serious complication occurs, you’ll receive treatment that focuses on regulating your heart rhythm and rate and preventing blood clots. This may include taking medications like:

  • blood thinners, such as warfarin (Coumadin), apixaban (Eliquis), or aspirin
  • beta-blockers to control your heart rate, like metoprolol or carvedilol
  • calcium channel blockers to slow your heart rate and regulate pumping strength, like diltiazem and verapamil
  • digoxin to slow your heart rate and the conduction of electrical signals through the heart
  • sodium channel blockers to slow electrical conduction through the heart, such as flecainide
  • potassium channel blockers to slow the electrical signals that cause AFib, like amiodarone

If medications don’t control your AFib, treatments include electrical cardioversion or ablation.

For electrical cardioversion, a doctor sedates you and delivers an electrical shock from outside your body to reset the electric signals in your heart.

With ablation, a specialist inserts a catheter — usually through the groin — and uses lasers, freezing, or another method to destroy small areas of cardiac tissue. After the ablation, these areas of the heart won’t function and won’t conduct abnormal heart signals.

Silent AFib is the same as other types of AFib, but it can develop without symptoms that could prompt early treatment. Since doctors don’t diagnose many cases of silent AFib until serious consequences occur, it generally has worse outcomes than other forms of AFib.

Talk with your healthcare team about your risk factors for AFib and getting regular screenings for your heart health.