Yes, atrial fibrillation (AFib) can lead to several complications, including an enlarged heart. A bigger heart is weaker, not stronger and, as a result, it can become harder for the heart to pump blood out to meet the body’s needs.

Atrial fibrillation (AFib) is a common heart rhythm disturbance in which the heart’s upper chambers beat chaotically instead of with a steady rhythm. AFib can lead to several serious complications, including an enlarged heart. This can cause heart failure and other life threatening conditions.

With proper treatment, AFib is manageable, and the risk of complications is reduced. If an enlarged heart (cardiomegaly) does develop, your doctor may prescribe one or more medications to support healthy heart function.

An AFib diagnosis means that instead of beating in a coordinated rhythm with the heart’s lower chambers (ventricles), the upper chambers (atria) beat rapidly and irregularly.

As a result, the heart has to work harder to pump blood out to meet the body’s needs. AFib also means that blood does not move through the heart properly and can pool in the atria, potentially forming a dangerous blood clot that could travel toward the brain and cause a stroke.

AFib is associated with an enlarged heart. It can both cause enlargement of the atria or result from atrial enlargement.

Additionally, AFib can result in enlargement of the ventricles (cardiomegaly). Specifically, it can cause a condition known as atrial fibrillation-mediated cardiomyopathy. This is because AFib makes it harder for the heart to supply the body with oxygenated blood. The burden may eventually weaken the heart muscle, resulting in enlargement of the ventricles.

For many people, AFib causes no noticeable symptoms. It might be detected only in a routine physical examination. When AFib symptoms are present, symptoms can include:

  • chest pain
  • dizziness
  • fatigue
  • heart palpitations
  • shortness of breath
  • “thumping” sensation in the chest
  • exercise intolerance

The main test used to diagnose AFib is an electrocardiogram (ECG), which uses electrodes placed on the skin to record the heart’s electrical activity. If a heart is in AFib, an ECG should detect it and record the abnormal heart rhythm (arrhythmia).

But some people with AFib may go through periods when the heart beats normally and have occasional episodes of a chaotic heart rhythm. In these cases, doctors often recommend a wearable ECG device, such as a Holter monitor, to capture evidence of AFib at times when an individual is not in the doctor’s office.

Normally, a well-paced electrical system keeps your heart beating consistently 24 hours a day, speeding up in moments of stress or physical exertion only to return to a normal rhythm when the stress or activity subsides.

But when a rhythm disturbance (arrhythmia) like AFib develops with the electrical system, it can affect your heart function in several ways.

For example, in AFib, the heart does not move blood in and out of the heart efficiently. Blood that pools in the atria can form a blood clot. If the clot eventually leaves the heart, it can head to the brain and block blood flow in an artery supplying blood to the brain or in an artery within the brain.

In either event, there’s the possibility an ischemic stroke can occur.

The other major risk associated with AFib is that the heart pumps harder with every heartbeat to overcome the weaker, less efficient beating of the atria.

Just as you can pump up your biceps or other muscles with vigorous workouts, parts of the heart can get bigger from having to pump harder, too. Only in this case, a bigger heart is weaker, not stronger.

An enlarged heart is a sign that the heart is straining to pump enough blood to satisfy the needs of the body’s organs, muscles, and other tissue. Over time, the additional hard work the heart performs can cause it to weaken and pump blood less efficiently with every contraction.

A weakened heart eventually becomes heart failure, a life threatening condition that affects about 6.2 million adults in the United States, according to the Centers for Disease Control and Prevention (CDC).

While AFib can lead to an enlarged heart, this 2022 review update confirms research from 2018 highlighting that heart failure and an enlarged heart face also elevate risks of developing AFib.

Enlarged heart treatments, particularly when heart failure is present, may include a combination of medications and procedures or devices aimed at maintaining a normal heart rhythm to support decreasing the burden on the heart muscle.

A 2020 study suggests that the use of medications and implanted devices (if needed) can significantly improve the outcome for people with heart failure.

The American Heart Association also recommends the same treatment — using medications and implanted devices.

Medications prescribed to someone with AFib and cardiomegaly may include one or more of the following:

  • antiarrhythmics, which are medications that help manage your heartbeat.
  • anticoagulants, which are medications known as “blood thinners” that help reduce stroke risk by interfering with the body’s natural blood-clotting process
  • beta-blockers, which are drugs that help slow the heart rate
  • diuretics, which are medications that reduce fluid levels in the body and help maintain fluid volume balance

In more serious cases of heart failure, you may need a left ventricular assist device (LVAD), which acts as an artificial pump that supports your heart’s natural pumping ability. An LVAD may be enough to maintain heart function, or it may be used as a bridge device while you await a heart transplant.

The association between AFib and an enlarged heart works both ways.

Having AFib means your heart may pump harder and grow larger in trying to compensate for the irregular heart rhythm. Likewise, if some other cause has led to cardiomegaly, having an enlarged heart may cause AFib or other arrhythmias.

Because an enlarged heart is just one complication of AFib, it’s important to work with your healthcare team in managing this common arrhythmia. Getting the right treatment can help keep your heart strong and pumping efficiently.