Can You Have AFib and Not Know It?

Summary Paragraph

Many people assume a heart rhythm disorder would be obvious. Surprisingly, that’s not always the case.

Some people with atrial fibrillation (AFib) experience noticeable symptoms like palpitations, fatigue or shortness of breath. Others feel completely normal and don’t realize they have AFib until it’s discovered during a routine exam, after a smartwatch alert or while being evaluated for another condition.

That can be concerning because AFib can increase the risk of stroke, even when symptoms aren’t present.

“One of the biggest misconceptions about AFib is that you would always know if you have it,” explains Mohamad Sinno, MD, an electrophysiologist at St. Elizabeth. “In reality, some people have little to no symptoms and don’t realize anything is wrong until it’s detected during a medical evaluation or on a personal device such as a smartwatch or a blood pressure machine.”

Key Takeaways

• AFib can happen without obvious symptoms. Smartwatch alerts can be helpful but are not a diagnosis.
• Symptoms such as fatigue, dizziness, shortness of breath or a racing heartbeat should be discussed with a healthcare provider.
• Early detection can help reduce the risk of stroke and other complications.

What Is AFib?

AFib is the most common heart rhythm disorder in people older than 40. It occurs when the upper chambers of the heart begin beating irregularly, causing the heart’s electrical system to become disorganized.

Some people experience episodes that come and go. Others may remain in AFib for longer periods of time.

Because the condition can affect how blood moves through the heart, untreated AFib can increase the risk of blood clots and stroke.

Why Don’t Some People Notice Symptoms?

AFib affects everyone differently.

Some people immediately notice:

• Heart palpitations.
• A racing heartbeat.
• Fluttering in the chest.
• Shortness of breath.
• Fatigue.
• Dizziness.

Others don’t experience any of those symptoms.

In some cases, symptoms develop gradually and are easy to attribute to something else.

“Patients often assume they’re simply getting older, out of shape or more tired than usual,” says Dr. Sinno. “They don’t always connect those changes to a heart rhythm problem.”

Signs That Are Easy to Dismiss

The signs of AFib aren’t always obvious. In many cases, people don’t realize a heart rhythm problem could be causing the way they feel.

People commonly attribute symptoms to:

• Aging.
• Stress.
• Poor sleep.
• Dehydration.
• Busy schedules.
• Lack of exercise.

You may notice:

• Less energy than usual.
• Reduced exercise tolerance.
• Becoming winded more easily.
• Fatigue that seems out of proportion to your activity level.

While these symptoms can have many causes, they shouldn’t automatically be ignored.

Can a Smartwatch Identify AFib?

Wearable devices might detect potential heart rhythm issues.

Many smartwatches and fitness trackers can identify irregular heart rhythms and notify users when something appears abnormal.

These alerts can be helpful, but they aren’t a diagnosis.

“Don’t panic, but don’t ignore it,” says Dr. Sinno. “A smartwatch alert doesn’t necessarily mean you have AFib, but it does mean you should follow up with a healthcare provider who can determine what’s really going on.”

If you receive an alert, it’s a good idea to share that information with your healthcare provider.

Why Early Detection Matters

Even when AFib isn’t causing noticeable symptoms, it can still increase the risk of complications.

One of the most significant concerns is stroke.

When the heart beats irregularly, blood may not move through the heart as efficiently as it should. Over time, this can increase the risk of clot formation. If a clot travels to the brain, it can cause a stroke.

The good news is that treatment options are available to help reduce risk and improve quality of life.

What Should You Do If You Think You May Have AFib?

If you’re experiencing symptoms such as palpitations, shortness of breath, fatigue or dizziness, don’t assume they’re simply part of getting older.

Start by discussing your symptoms with your primary care provider or cardiologist. They can evaluate your symptoms and determine whether additional testing is needed. If AFib is diagnosed, they may refer you to a cardiac electrophysiologist for specialized care and treatment recommendations.

If you’ve received an alert from a smartwatch or have concerns about your heart rhythm, it’s worth bringing that information to a medical professional who can determine whether additional testing is appropriate.

The Only Way to Know Is to Get Checked

AFib can feel different for different people. If you notice new or recurring symptoms, it’s important to talk to your healthcare provider as soon as possible. Paying attention to changes in how you feel and following up on potential warning signals can help identify AFib earlier and reduce the risk of serious complications, such as stroke.

Call (859) 331-3353 to speak with an Arrhythmia Center nurse navigator, who can provide information and help guide you to the most appropriate next step.

Medically reviewed by Mohamad Sinno, MD, on 8/7/2026