Signs and Symptoms of Atrial Fibrillation

<p>Tetra Images - Erik Isakson / Getty Images</p>

Tetra Images - Erik Isakson / Getty Images

Medically reviewed by Rafle Fernandez, MD

Atrial fibrillation (AFib) is a type of abnormal heart rhythm—also known as arrhythmia. This condition can occur when your heart's upper chambers (called the atria) begin to fibrillate, or beat rapidly in a disorganized way. Many people have AFib without even knowing, mostly because the condition doesn't always cause symptoms. If you do have symptoms, you'll likely experience palpitations, shortness of breath, or fatigue.


The most common symptom of AFib is palpitations—or, a skipped, rapid, or irregular heartbeat. This can cause a fluttering sensation in your chest and make your pulse feel irregular. To understand why this happens, it's helpful to know what's happening in the heart's electrical system and how your heart rate functions.

Normally, the sinus node, which is a bundle of cells in the upper left atrium, determines the heart rate. The sinus node creates an electrical impulse by sending out signals for the heart to beat in a regular pattern. Generally, a normal heart rate is when your heart beats 60 to 100 times per minute. In AFib, however, areas throughout your entire atria are sending out signals to your heart, which can cause an irregular rhythm.

Lightheadedness or Dizziness

Lightheadedness is another common symptom of AFib. The brain requires a lot of blood flow to function, so any reduction in blood flow can cause dizziness. AFib can reduce how well your heart pumps out blood, especially when the heart is beating rapidly and your blood pressure is low. Less commonly, severe low blood pressure and a significant lack of blood flow to the brain can cause fainting, particularly in people with AFib who are over 70 years of age.

Exercise Intolerance

Sometimes the first symptom of AFib you might notice is exercise intolerance. You may find difficulty finishing your typical exercise routine or feel more winded after a typical workout than normal.

Researchers have identified a couple of possible reasons why your workouts might feel more difficult. During exercise, your heart needs to keep up with how much blood flow your body needs. But during AFib, your heart isn't able to respond properly to the increase in heart rate you have when you're exercising. Additionally, AFib also affects your heart's ability to pump blood efficiently, which can increase the pressure in your heart when your heart rate is too high.

Chest Pain

Because AFib can rapidly increase your heart rate, it's common to experience chest pain. Your heart is a constantly working muscle that requires a lot of blood flow. When you have AFib and your heart rate is too fast, you may have a reduction in blood flow that leads back to the heart. This is a condition called cardiac ischemia.

Having cardiac ischemia can increase your risk of experiencing chest discomfort, pressure, tightness, and aching—especially in the center of your chest or upper abdomen. The pain can eventually radiate up to the left side of the chest, left arm, or jaw.

Keep in mind: chest pain can be a sign of more serious heart conditions, like a heart attack. If you develop chest discomfort, you should seek medical attention immediately.

Shortness of Breath

AFib can cause a general feeling of shortness of breath, even when you're not working out. When your heart isn't performing efficiently, there can be a backup of blood flow into your lungs. This leads to fluid in the lungs, which can lead to shortness of breath.

It's worth noting that AFib and heart failure commonly occur together, and people with heart failure are especially prone to backup of fluid in the lungs. As a result, those with heart failure and AFib are at an increased risk of being short of breath, especially while resting.


Fatigue is a common symptom of AFib, that can also be a sign of many other conditions. Fast heart rates and inefficient heart function during AFib might lead to a general feeling of exhaustion. Sometimes you might not have any specific heart-related symptoms but "not feeling right" or experiencing extreme tiredness even if you've gotten rest could point to AFib.

When to Contact a Healthcare Provider

If you suspect you might have AFib or experience any symptoms of AFib it's time to schedule a visit with your healthcare provider for proper diagnosis. They will ask about your medical history and perform a physical exam. If you happen to be experiencing AFib at the time of the visit, an electrocardiogram (a test that records the electrical signals in your heart) will diagnose it. Your provider can also order other lab and imaging tests to look for other causes of your symptoms.

Any concerning symptoms like chest pain or sudden shortness of breath should prompt a visit to the emergency room to rule out a life-threatening heart attack. If AFib symptoms are severe, you may be admitted to the hospital to help control your heart rate or undergo a procedure called a cardioversion to get your heart back into a normal rhythm.

Questions to Ask Your Provider

If you decide to seek further care, consider asking your healthcare provider the following questions:

  • Can my smartwatch identify AFib?

  • If my symptoms come and go, do you recommend a heart monitor?

  • Do I need to worry about stroke risk with AFib?

  • If I have AFib, how can I better control my heart rate?

  • Could my symptoms be a sign of another condition besides AFib?

A Quick Review

AFib is a type of heart arrhythmia that causes rapid beating of the heart's upper chambers. Fast and irregular heart rates and inefficient blood flow can cause symptoms like palpitations, lightheadedness, shortness of breath, fatigue, chest discomfort, and exercise intolerance. It's important to see your healthcare provider if you have signs of AFib, since this condition increases the risk of stroke and can cause other complications, like heart failure.

Frequently Asked Questions

What does an AFib episode feel like?

AFib feels different for different people. Some people may not notice any symptoms during an AFib episode, while others may have disabling symptoms. An AFib episode can occur alongside palpitations, shortness of breath, or fatigue, among other symptoms.

What is the average life expectancy after developing Afib?

AFib can shorten life expectancy, given its association with complications like stroke, heart failure, and heart attack. One study published in 2020 showed that 10 years after a diagnosis of AFib, those with AFib lost 2 years of life compared to those without AFib. However, an individual's life expectancy after being diagnosed with an arrhythmia like AFib depends a lot on underlying factors, such as age, lifestyle habits, and other medical conditions.

Can atrial fibrillation go back to normal?

AFib episodes can sometimes go back to a normal rhythm. Early on in the course of AFib, episodes may be short-lived. Over time, AFib can become more persistent or permanent. However, treatments like antiarrhythmic medications or medical procedures such as an ablation can help your heart stay in a normal rhythm.

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