Understand what Apple Watch ECG records, which models support it, what screening research shows, and why a watch result cannot rule out a medical problem.
Apple Watch ECG records a short, single-lead electrical trace that can be shared with a clinician. It is not continuous ECG monitoring, and a sinus-rhythm classification does not establish that your heart is healthy. Apple Watch SE models do not support the ECG app.
Correction, September 5, 2026: removed unsupported doctor endorsements and accuracy guarantees, corrected SE compatibility, and separated screening-study outcomes from ECG classification accuracy. This is a research summary, not an iPhoneExtra clinical test.
Who can use the ECG app?
Apple’s ECG support guide identifies supported Series 4-and-later and Ultra models, with country and region restrictions. The app is not intended for people under 22. Check the exact model and regional feature list; an optical heart-rate sensor alone does not provide ECG capability.
What does the recording tell you?
Follow the app’s instructions to make a 30-second recording while resting your arms and touching the Digital Crown. The available classifications and heart-rate ranges depend on the ECG app version. An inconclusive or poor recording is not a diagnosis. The waveform and recorded symptoms can be exported from Health for professional review.
What EQUAL studied
The EQUAL trial record describes smartwatch-assisted atrial-fibrillation screening in older people at elevated risk. The published randomized trial reported more newly diagnosed AFib in the watch group than in standard care: 21 participants versus five, or 9.6% versus 2.3%.
That is a result for a screening program in a defined population, not a sensitivity percentage for every ECG recording. It does not establish that all current watch models are equally accurate or that buying a watch prevents stroke. Screening involved follow-up; the watch was not a substitute for clinical assessment.
Why there is no single accuracy percentage
Study performance depends on the population, reference method, app version and treatment of unreadable recordings. An analysis that excludes unclassified traces answers a different question from one that counts them as failures. A clinician reading a trace is also a different process from the watch algorithm assigning a label. Do not combine these into a “100% accurate” headline.
What the app cannot rule out
Apple’s ECG instructions for use explain its limitations, including that it cannot detect a heart attack. A reassuring result does not rule out other heart conditions. Do not start, stop or change medication based on a watch classification.
If you receive an AFib classification without a previous diagnosis, discuss it with a clinician. If you feel unwell, seek care based on your symptoms regardless of the displayed result. For severe chest pain, fainting or serious breathing difficulty, seek urgent medical help rather than repeating watch tests before deciding.
Before buying for a health concern
Ask your clinician whether recording symptoms or ECG traces would help your particular care. Choose a device for the feature it actually provides, then verify regional availability. ECG, optical irregular-rhythm notifications and blood oxygen are separate functions; our blood oxygen evidence review covers the last of these.
