My smartwatch says my heart rhythm is irregular: can I trust it and what should I do?

No. According to the practical guide published by the European Heart Rhythm Association (EHRA) in the journal Europace in 2022, an unusual reading from an ordinary consumer device is not a diagnosis: it must be confirmed with an ECG, and the doctor must review the recording personally. An unusual result should be assessed by a team that includes an arrhythmologist or cardiologist. The guide covers smartwatches, wristbands, chest straps, rings, earbuds, adhesive patches and handheld ECG devices.

AFib Matters, the patient website run by the ESC and EHRA, says that devices made for consumers are not always accurate and have a low threshold for reporting abnormalities, meaning they give alerts easily. Such alerts often cause anxiety. According to a review of the 2024 ESC/EACTS atrial fibrillation guidelines, the evidence on consumer devices (smartwatches and the like) is still too limited to give a clear recommendation. That is why no accuracy percentage or rating is given here for any model. Counting your pulse by hand is not the answer either: according to AFib Matters, it may raise a suspicion of irregularity, but it cannot reliably confirm it, especially when the heart is beating fast.

The sources above mainly talk about unusual readings, not about a nice-looking recording. According to AFib Matters, when you feel palpitations, what matters most is an ECG taken at the time of the symptoms. So if the watch shows a calm rhythm but you keep feeling palpitations, dizziness or shortness of breath, tell your doctor. Only an examination decides which test is needed. The recording on the watch may be useful information for the doctor, but the final conclusion is made after an ECG and an examination by a doctor.

1. Check first: if you have severe chest pain, severe shortness of breath or fainting, call 103 right away.
2. Do not panic: sit comfortably and calm down for a few minutes. Among the causes of feeling palpitations, AFib Matters also lists anxiety, caffeine and conditions not directly related to the heart; the cause is determined by the doctor.
3. Save the recording: do not delete the recording in the app; take a screenshot or save it as a file. If the alert has happened several times, save all of them with their dates.
4. Write down the time, how long it lasted, what you were doing at that moment and how you felt. AFib Matters recommends keeping a symptom diary (duration, triggers, accompanying symptoms) before seeing a doctor.
5. Show the recording to a doctor: according to the EHRA guide, it must be reviewed by a doctor.
6. Have an ECG, if possible at the time of the symptoms. If the symptoms are rare, the doctor chooses longer monitoring (for example, an event recorder that you switch on when a symptom occurs).
7. Bring the watch and the phone on which the recording can be opened to your appointment, so that the doctor can review the recording personally.

According to the EHRA authors, the devices may be especially useful for arrhythmias that come and go: such episodes are hard to record at the very moment they happen. At the same time, the authors advise not buying an over-the-counter device that has no official approval, and not monitoring your heart rhythm constantly without a medical reason. If the watch is increasing your anxiety, tell your doctor: they decide whether to continue or stop the monitoring.

According to AFib Matters, fast and debilitating episodes, as well as episodes with shortness of breath, dizziness, fainting or chest pain, require urgent medical attention. At such a moment, the number on the watch is secondary.

If there are no such symptoms but the alert keeps coming back, see a doctor at a planned appointment.