My watch says I have AFib
An AFib alert is worth checking. Here is what the alert means, how to record a useful ECG, and what happens at your visit.
From Dr. Kenny Civello, cardiologist and electrophysiologist
Your watch is good at noticing an irregular pulse. It cannot tell you for sure that you have AFib, and it cannot tell you what to do about it. A doctor reads the tracing, confirms the rhythm, and checks your stroke risk.
How it notices
A light sensor on the back of the watch checks your pulse now and then. If the rhythm looks irregular several times in a row, you get an alert.
It can be wrong
Extra beats, movement, and a loose band can all set off an alert. A doctor has to look at a tracing to be sure.
Why it matters
AFib makes a stroke about five times more likely. Finding it early lets us lower that risk.
Why the alert and the ECG are different
The alert comes from your pulse, measured with light. It only sees the timing of each beat. The ECG app records the electrical signal of your heart for 30 seconds. That shows the actual rhythm, and it is what a doctor can read. An alert tells you to look. An ECG lets us see.
Record a useful ECG
If your watch can record an ECG, do it when you get an alert and any time you feel your heart racing or skipping.
Sit down
Rest your arms on a table or your lap. Stay still and do not talk.
Snug the band
The watch should sit firmly on the wrist you chose in its settings.
Touch the sensor
Hold a fingertip from your other hand on the crown or button your watch tells you to touch. Do not press down.
Hold for 30 seconds
Keep still until it finishes. If the result is unclear, wait a minute and record again.
Write it down
Note the time and what you felt, if anything. Then save or share the recording.
How to share a recording
Most heart apps let you save an ECG as a PDF. On an iPhone, open the Health app, tap Browse, then Heart, then Electrocardiograms, and choose the option to export a PDF. Other brands have a share or export button in their heart app. Bring the PDFs to your visit or have them ready on your phone.
What your ECG result means
Watch apps use a few standard labels. Here is what each one means for you.
Atrial fibrillation
The app saw a pattern that looks like AFib. Save it and call us to set up a visit. If the tracing is clear, a doctor can often confirm AFib from it.
Sinus rhythm
Your rhythm was normal during those 30 seconds. AFib can come and go, so if alerts keep coming, still tell us.
Inconclusive
Extra beats, a very fast or slow heart rate, or a pacemaker can confuse the app. Record again later. Save it either way.
Poor recording
Usually movement or a loose band. Rest your arms, snug the band, and try again.
What happens at your visit
The goal is to confirm the rhythm, find the cause, and protect you from stroke.
We read your recordings
We look at the tracings themselves, not just the label the app gave them.
An ECG in the office
A standard 12 lead ECG takes a few minutes and shows your rhythm in more detail.
A heart monitor, if needed
If AFib comes and goes, a small patch worn for days to weeks can catch it. About heart monitors
Tests for causes
Blood tests, including thyroid, and often an ultrasound of the heart called an echocardiogram.
Your stroke risk
A score based on your age, sex, blood pressure, diabetes, heart failure, blood vessel disease, and any past stroke. It tells us whether you need a blood thinner.
A plan
Treatment for the rhythm if you need it, and work on the habits that drive AFib. See the AFib risk guide.
Common questions
Can my watch miss AFib?
Yes. The background checks run only now and then, mostly when you are still. No alert does not mean no AFib. If you feel a racing or irregular heartbeat, record an ECG right then.
I got an alert, but my ECG says normal rhythm. Now what?
AFib can stop on its own within minutes or hours. Save both and tell us. Record another ECG the next time you get an alert or feel something.
Should I start taking aspirin?
No. Aspirin does not prevent AFib strokes well, and it raises bleeding risk. If you need a blood thinner, we will choose one with you.
The alerts make me anxious. Can I turn them off?
That feeling is common. Talk with us before you turn them off. Once we know your rhythm, we can decide together which alerts are worth keeping.
I already have AFib. Is the watch still useful?
Yes. Recordings help us see whether treatment is working. Some watches have a separate setting for people already diagnosed that shows how much time you spend in AFib each week. Ask us whether to turn it on.
Which watch should I buy?
Choose one with an FDA cleared ECG feature. The brand matters less than wearing it snug and recording when you have symptoms.
Other guides
Lowering your AFib riskLowering your blood pressureEating for your heartSleeping wellLiving with POTSGetting ready for your ablationLiving with a pacemaker or ICDThis page is general education for my patients. It does not replace advice from your own doctor. Watch alerts and ECG apps are not a diagnosis.
Based on: Joglar JA, et al. 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation. Circulation. 2024.