Useful trend tools with some genuinely medical features - the FDA cleared the Apple Watch ECG app to detect atrial fibrillation - but not diagnostic devices.
Optical heart-rate tracking handles trends well and drifts with motion, loose fit, or tattoos. An AFib notification earns a doctor visit; a normal reading does not erase a symptom; and no smartwatch feature replaces a professional ECG.
What to do
Common questions
How accurate are smartwatch heart readings?
Better than gadgets, short of medical devices - and the exact line depends on the feature. Optical heart-rate tracking (the green-light sensor on the back) is good at trends - resting rate, workout zones, sleep patterns - and can drift during intense motion, loose fit, tattoos, or cold skin. The medically serious features are the FDA-cleared ones: the FDA authorized the Apple Watch ECG app to detect atrial fibrillation and normal rhythm, plus an app that analyzes pulse data to flag irregular rhythms suggestive of AFib. Those notifications earn a doctor visit, and studies behind the clearance were real trials. What the watch is not: a diagnostic instrument. A normal reading does not clear a symptom, an odd one needs a clinician's confirmation, and no smartwatch feature replaces an ECG read by a professional. Use it as an early-warning layer that hands you to a doctor, which is genuinely valuable. Pymander, a free AI doctor available 24/7 by text, can help you decide what a notification means.