Yes, several modern smartwatches can help detect signs of atrial fibrillation (AFib), the most common form of irregular heart rhythm. Watches from Apple, Samsung, Fitbit (Google), Garmin, and Withings use optical heart-rate sensors and, in many cases, an on-wrist electrocardiogram (ECG) to flag rhythms that look like AFib. It’s important to be precise about what this means: these features can indicate a possible problem and prompt you to seek care, but they do not diagnose, treat, or rule out AFib. Only a qualified healthcare professional can confirm a diagnosis, typically with a medical-grade ECG.
How smartwatches screen for atrial fibrillation
- Uses green LEDs to track beat timing at the wrist
- Runs passively in the background, even during sleep
- Sends an irregular rhythm notification, no action needed
- You touch the watch for ~30 seconds to record electrical activity
- Classifies the reading as sinus rhythm, possible AFib, or inconclusive
- Single-lead recording you can export as a PDF for your doctor
Smartwatches use two complementary technologies to look for signs of AFib. Understanding the difference helps you interpret what an alert actually means.
PPG (photoplethysmography) for background monitoring
The green LEDs on the back of most watches measure blood-volume changes in your wrist. This is called photoplethysmography, or PPG. By tracking the timing between heartbeats in the background, the watch can spot the irregular, erratic pattern that often accompanies AFib. When the software detects enough irregular readings over time, it sends an “irregular rhythm notification.” This passive screening runs while you rest or sleep and requires no action from you.
ECG (electrocardiogram) for an on-demand reading
An on-wrist ECG works differently. You place a finger on the watch (or its crown/bezel) to complete a circuit and record the heart’s electrical activity for roughly 30 seconds. The app then classifies the result as sinus rhythm, possible AFib, or inconclusive. A smartwatch ECG is a single-lead recording, far simpler than the 12-lead ECG used in clinics, but it captures more detail than PPG and can usually be shared with your doctor as a PDF.
Which smartwatches offer AFib-related features?
Most flagship health watches now include irregular-rhythm screening, and many add an ECG app. Availability of specific features can depend on your region and regulatory clearances, so always confirm on the manufacturer’s site for your country.
| Brand / line | On-wrist ECG | Irregular rhythm alerts (PPG) | Notable detail |
|---|---|---|---|
| Apple Watch (Series 4 and later, Ultra 2) | Yes | Yes | FDA-cleared ECG app; “AFib History” estimates time spent in AFib for diagnosed users |
| Samsung Galaxy Watch | Yes | Yes | ECG and rhythm features run through Samsung Health Monitor; setup varies by region |
| Fitbit (Sense, Charge, and others, by Google) | Yes | Yes | Irregular Heart Rhythm Notifications plus an ECG app on supported models |
| Withings ScanWatch line | Yes | Yes | Hybrid analog design with medical-grade ECG and rhythm alerts |
| Garmin (select models) | Yes (on supported models) | Yes | ECG app availability is limited and region-dependent |
If ECG is a priority for you on a budget, our roundup of affordable smartwatches with an ECG feature is a useful starting point, and our list of the top 5 smartwatches for health monitoring in 2025 covers broader wellness tracking.
How accurate are these features?
Manufacturers and published clinical studies generally report that on-wrist ECG and PPG screening perform well at identifying AFib when a clear reading is captured, but accuracy is not absolute. A few realities are worth keeping in mind:
- False negatives happen. AFib is often intermittent (“paroxysmal”). If your heart is in normal rhythm at the moment of a reading, the watch can show sinus rhythm even if you experience AFib at other times.
- False positives happen. Motion, poor skin contact, tattoos, cold hands, or arrhythmias other than AFib can produce inconclusive or misleading results.
- These are screening tools, not diagnostics. The U.S. Food and Drug Administration clears these features as aids that are not intended to replace traditional diagnosis or treatment, and generally not for people already diagnosed with AFib (except features designed specifically for them).
- A “normal” result is not reassurance. If you have symptoms such as palpitations, chest pain, shortness of breath, or fainting, contact a healthcare professional regardless of what your watch shows.
What to do if your watch flags an irregular rhythm
- Don’t panic. A single alert is a prompt to follow up, not a diagnosis.
- Record an ECG if your watch supports it, while sitting still, and save the PDF.
- Note your symptoms, the time, and what you were doing.
- Contact your doctor and share the data. They may recommend a clinical ECG or a longer-term monitor to confirm what’s happening.
- Seek emergency care for severe symptoms like chest pain, severe shortness of breath, or fainting.
Choosing a watch for heart-rhythm screening
If AFib screening is your main reason for buying, prioritize a model with both PPG-based notifications and an on-demand ECG, confirm the features are cleared and available in your country, and check that the companion app exports readings you can share with a clinician. Comfort and consistent wear matter too, because background screening only works when you actually wear the watch, including overnight. For broader guidance, see how to choose the right smartwatch for your needs, and if rugged battery life appeals to you, our Garmin Instinct 3 review looks at one long-lasting option. Heart-rhythm tools are part of a wider shift covered in the latest trends in smartwatch technology.
Frequently asked questions
Is a smartwatch ECG the same as one from a hospital?
No. A smartwatch records a single-lead ECG, while a clinical ECG typically uses 12 leads for a far more complete view of the heart’s electrical activity. The watch reading can be a helpful early signal and conversation starter, but doctors rely on medical-grade testing to confirm AFib.
Can a smartwatch detect AFib while I sleep?
PPG-based irregular rhythm notifications can run passively in the background, including overnight, and may flag irregular readings during sleep. The ECG app, by contrast, requires you to be awake and touching the sensor to take a reading.
Should I rely on my watch instead of seeing a doctor?
No. These features are designed to encourage you to seek professional care, not to replace it. If you have symptoms or a flagged alert, talk to a qualified healthcare professional. A watch can also miss intermittent AFib, so a normal result should never delay care when you feel unwell.
Do these health features need a subscription or a specific phone?
Core ECG and irregular-rhythm features generally work without a subscription, but the companion app and phone compatibility matter, and some platforms tie advanced insights to a membership. Connectivity also plays a role; if you want standalone alerts, see our guide on adding a smartwatch to your Verizon plan.
Medical disclaimer
This article is general information only and is not medical advice. Smartwatch heart-rhythm features are screening aids that may flag a possible issue; they do not diagnose, treat, cure, or prevent any condition. Always consult a qualified healthcare professional about your heart health and before making decisions based on data from a wearable device. If you think you may be experiencing a medical emergency, call your local emergency number.