My Smartwatch Says I Have AFib. What Should I Do?

Dr. Matt SegarBy Matthew W. Segar, MD, Cardiac Electrophysiologist, Ascension St. Vincent · Last reviewed

Need an appointment? Call Carmel (317) 338-6666 or New Castle (765) 521-1461. Emergency: call 911.

The short answer

A smartwatch alert means your watch noticed an irregular pulse that could be atrial fibrillation (AFib). It is a warning, not a diagnosis. You need an ECG or heart monitor to know for sure. Call 911 for chest pain, fainting, severe shortness of breath, or stroke signs. Otherwise, make a regular appointment.

When to call 911 instead

Do not wait for an appointment if you have:

  • Chest pain or pressure
  • Severe shortness of breath
  • Fainting or nearly fainting
  • Stroke signs: face drooping, arm weakness, trouble speaking, sudden vision loss, or sudden confusion

What the alert means

Most smartwatches shine a light on your wrist and track the pulse in the blood flow. If the beats look irregular over several checks, the watch sends an alert. Some watches can also record a single-lead ECG when you touch the crown or a sensor.

AFib is a common heart rhythm problem where the top chambers of the heart quiver instead of squeezing normally. It can make the pulse fast and irregular. It can also cause no symptoms at all.

How accurate are these alerts? In the Apple Heart Study (more than 400,000 people), about half of one percent got an irregular-pulse notification. Of those who then wore an ECG patch for a week or so, 34% (about one in three) had AFib detected on the patch. When the patch happened to be recording at the moment of an alert, AFib was confirmed 84% of the time. Other brands work differently, so these numbers do not apply to every watch. The takeaway is simple: many alerts are real, many are not, and only a proper recording can tell the difference.

Why it matters

AFib can let blood pool in the heart and form clots. A clot that travels to the brain causes a stroke. Strokes from AFib can often be prevented with the right treatment, but only if we know you have it. That is why an alert is worth a visit even if you feel fine.

What to do now

  1. Stay calm. An alert is not an emergency if you feel okay.
  2. Save the evidence. Take a screenshot of the alert. If your watch has an ECG feature, record an ECG while you have symptoms, and try again later when you feel normal. Here is how to export them for your visit.
  3. Write down what you notice. Note the date, time, what you were doing, and any symptoms like a racing heart, dizziness, or tiredness.
  4. Keep taking your usual medicines. Do not stop or start anything without talking to your doctor.
  5. Schedule a visit. Tell the office you had a smartwatch AFib alert.

What happens at the visit

  • A 12-lead ECG in the office.
  • A look at your history, medicines, blood pressure, and risk factors such as sleep apnea, alcohol, thyroid disease, and heart disease.
  • Often a wearable heart monitor for one to several weeks if the ECG is normal but the alert was real or repeated.
  • Sometimes an ultrasound of the heart (echocardiogram) and blood tests.

If AFib is confirmed, we decide together about stroke prevention, controlling symptoms, and whether a procedure like ablation makes sense. You can read more in my AFib overview.

Common questions

Can a smartwatch really diagnose AFib?

No. A watch can flag a pattern that looks like AFib. A doctor confirms it with an ECG or a heart monitor that records the actual rhythm. The watch is a good screening tool, but it can be wrong.

Can I get a false alert?

Yes. Motion, a loose band, and extra heartbeats (PVCs and PACs) can look like AFib to a watch. That is why I still want to see a confirmed recording before making a diagnosis.

Should I start or stop a blood thinner on my own?

No. If you already take a blood thinner, keep taking it until we talk. If you do not take one, do not start one because of a watch alert. The decision depends on your stroke risk and bleeding risk, which we work out together.

I feel fine. Do I still need to be seen?

Yes. AFib often causes no symptoms, and the main danger of untreated AFib is stroke. A symptom-free alert is still worth checking out.

How quickly do I need to be seen?

If you feel well, a regular appointment in the coming days to weeks is usually appropriate. Call sooner if the alerts keep happening or you are getting symptoms. Go to the emergency room for the warning signs listed above.

Make an appointment

I see patients with heart rhythm problems at Ascension Medical Group St. Vincent in Carmel and New Castle, Indiana. To schedule, use my Ascension page or call the office.

View my Ascension profile

References

  1. Perez MV, et al. Large-scale assessment of a smartwatch to identify atrial fibrillation. N Engl J Med. 2019;381:1909-1917.
  2. Joglar JA, et al. 2023 ACC/AHA/ACCP/HRS guideline for the diagnosis and management of atrial fibrillation. Circulation. 2024;149:e1-e156.

This page is general education, not medical advice, and does not create a doctor-patient relationship. It cannot replace an exam or an ECG. If you think you are having an emergency, call 911. This is my personal website. It is not an official Ascension website. I also build health technology products, which are not promoted on this page.