Atrial Fibrillation

What is atrial fibrillation?

In a normal heartbeat, electrical signals travel through the heart in an organized pattern, and the upper chambers (the atria) squeeze in coordination with the lower chambers. In atrial fibrillation, the electrical activity in the atria becomes chaotic. Instead of contracting properly, they quiver — and the heartbeat becomes irregular and often fast.

AFib is the most common sustained heart rhythm disorder. It becomes more common with age, and it may come and go in episodes or become a persistent rhythm.

What does AFib feel like?

Common symptoms include a fluttering or pounding sensation in the chest, a racing or irregular pulse, fatigue, shortness of breath, reduced exercise tolerance, and lightheadedness.

Importantly, some people feel nothing at all. Silent AFib is discovered on a routine exam, an EKG, or increasingly on a smartwatch or fitness tracker. A device alert is not a diagnosis, but it is a good reason to be evaluated.

Why does atrial fibrillation matter?

Two reasons. First, the irregular rhythm itself can make you feel unwell and, if the heart rate stays high for a long time, can weaken the heart muscle over time.

Second, and more importantly: because the atria are not emptying completely, blood can pool and form a clot. If that clot travels to the brain, it causes a stroke. AFib substantially increases stroke risk, and strokes caused by AFib tend to be more severe. Assessing and managing that risk is the single most important part of AFib care.

How is AFib diagnosed?

An EKG can confirm AFib if it is present at that moment. Because AFib often comes and goes, diagnosis frequently requires longer monitoring — a Holter monitor worn for a day or two, or an extended ambulatory monitor or event recorder worn for weeks. An echocardiogram is typically performed to look at heart structure, valve function, and the size of the atria, and blood work checks for contributing factors such as thyroid disease.

How is atrial fibrillation treated?

Treatment addresses three separate questions:

• Stroke prevention — your risk is estimated using a validated scoring system, and anticoagulant (blood-thinning) medication is recommended when that risk is high enough to warrant it. This decision is made individually, weighing stroke risk against bleeding risk.
• Rate control — medications that keep the heart rate from running too fast, even if the rhythm remains irregular.
• Rhythm control — attempting to restore and maintain a normal rhythm, using medication, a scheduled electrical cardioversion, or referral for a catheter ablation procedure.

Treating the underlying contributors matters as well — particularly high blood pressure, sleep apnea, thyroid problems, alcohol intake, and excess weight, all of which can drive AFib.

This page is general health information, not medical advice. It cannot replace an evaluation by a physician who knows your history. Talk with your cardiologist or primary care physician about what applies to you.