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The Apple Watch heart rate feature you probably didn't realize existed
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Apple Watch includes an ECG app that captures electrical heart signals for more detailed analysis than the standard BPM monitor.
For engineers developing health-monitoring software, the ECG app shows how a wearable can move beyond simple pulse counting to detect arrhythmias by measuring cardiac electrical activity. Understanding its data output, user-interaction requirements, and regional limits helps when designing compatible apps or interpreting sensor data. It also highlights the balance between consumer-friendly usability and clinical reliability, informing decisions about when to trust the measurement.
Written by elseif from the cluster below · every claim links back to a sourceThe three things worth knowing
The ECG app records electrical signals from the heart via the Digital Crown and requires a snug watch fit and a 30-second still measurement.
Results are classified as sinus rhythm, atrial fibrillation, low or high heart rate, or inconclusive, with thresholds that differ between app versions.
Availability is limited to Apple Watch Series 4 or later (excluding SE) and Ultra models, requires the latest watchOS and iOS, and is not supported in certain countries.
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