Can You Have AFib and Not Know It?

From the WebMD Archives

The signs of atrial fibrillation (AFib) might seem pretty hard to ignore: a racing heart, trouble breathing, chest pain, and dizziness. You’d feel these symptoms and know something was wrong, right?

Maybe not. Nearly a quarter of the estimated 2.7 million people who have AFib have no symptoms at all. The problem is called silent AFib.

With this condition, the chambers on the top of your heart, called the atria, flutter instead of beating normally, which can put stress on the heart muscle. Since blood doesn’t get pushed through by full, strong beats, it can pool and form clots. In some cases, people only find out they have AFib when one of those blood clots causes a stroke.

The good news is that people with AFib can get treatment to manage their heart’s rhythm and keep the condition from getting worse. But first, you have to know you have it.

Diagnosis Without Symptoms

Most of the time, people with silent AFib learn they have it by chance.

“It is usually diagnosed by accident during a routine checkup,” says Jagmeet Singh, MD, PhD, who specializes in heart failure treatment at Massachusetts General Hospital. A doctor might find it during a physical exam or through a test that measures the electrical pulses of your heart, called an electrocardiogram (EKG).

Some people might have subtle signs of AFib but ignore them. These can include:

  • Fluttering in the chest
  • Fast and irregular heartbeat
  • Shortness of breath
  • Feeling weak or tired
  • Dizziness

Younger adults are more likely to have the basic symptoms, but are less likely to think they’re serious enough to get checked out, says Patrick Thomas Ellinor, MD, PhD, a cardiologist at Massachusetts General Hospital.

Know Your Risk

The first step is to know if you might have a greater risk for AFib. Usually, your odds are higher if:

  • You’re older. Although anyone can have the condition, your chances go up as you age.
  • You have high blood pressure, especially if you’ve had it for a long time and don’t control it.
  • Someone else in your family has AFib.
  • You have another heart condition, like valve problems or a history of heart attacks.
  • You have another medical problem, such as sleep apnea, thyroid problems, diabetes, or asthma.
  • You drink a lot of alcohol. Binge drinking (five or more drinks in 2 hours for men and four or more for women) may make AFib more likely.

Not everyone who has AFib will have these risk factors, but they can help you know if you should be on the lookout for symptoms.


What You Can Do

There’s no reason to go looking for AFib, Singh says. But if you’re concerned about your risk, talk to your doctor. She can tell you what signs to look for, including spikes in your blood pressure or heart rate, and which symptoms you shouldn’t ignore. Regular checkups can help her spot any changes to your heart’s rhythm.

If your doctor thinks there’s a problem with your heart, she’ll give you an EKG. The test measures how fast your heart is beating, its rhythm, and how strong its electrical signals are.

You can check for symptoms at home, too. Learn how to take your own pulse and check it daily for shifts over time, Ellinor says.

Smartphone apps that track your heart rate can help, too. These tools don’t check for problems, Ellinor says, but they can be a simple way to keep tabs on your symptoms before you see your doctor.

Remember that good habits such as a healthy diet, managing your weight, and not smoking make a difference, too, Singh says.

WebMD Feature Reviewed by Suzanne R. Steinbaum, MD on May 27, 2015



American Heart Association. “What is Atrial Fibrillation?” “Who is at Risk for Atrial Fibrillation?” “What are the Symptoms of Atrial Fibrillation?”

National Heart, Lung, and Blood Institute: “What Is an Electrocardiogram?”

Jagmeet Singh, MD, PhD, director, Cardiac Resynchronization Therapy Program, Massachusetts General Hospital.

Patrick Thomas Ellinor, MD, PhD, director, arrhythmia unit, Massachusetts General Hospital.

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