(Credit: Apple)

Apple unveiled the Apple Watch Series 4 in September and introduced a practically unprecedented ability to monitor heart health from a mobile device.

Apple's FDA-approved app can record an electrocardiogram (ECG) to monitor the user's heart rate and scan for possible problems. For example, the Watch can detect atrial fibrillation (AFib) which may lead to a stroke or heart attack.

SEE: Apple Watch Series 4 introduces ECG app and other health upgrades

The feature is now live for Watch Series 4 users in the US. To take an ECG on your Apple Watch, make sure the device is updated to WatchOS 5.1.2 and paired with an iPhone 5s or newer. Your iPhone should be running iOS 12.1.1.

Open Apple Health on the iPhone, and set up the ECG app with the instructions on-screen. If you don't see the prompt immediately, you can go to Health Data. From there, tap Heart and then tap Electrocardiogram.

Make sure your Watch fits snugly against your wrist. You can specify which wrist you prefer in the Apple Watch app. Simply open the app and tap My Watch. From there, tap General and then Watch Orientation.

The ECG app should be ready on your Watch. Before taking the ECG, rest your arms comfortably on a table or your lap.

Hold your finger on the Watch's crown for 30 seconds without pressing down. The device will display your results and any detected symptoms.

To log the test results, tap Save. You can find your results again by opening the Health app on your iPhone and tapping Health Data. From there tap Heart and then Electrocardiogram. There should be an option to export the data as a PDF to share with your doctor.

In addition to keeping track of your heart health, the Apple Watch Series 4 can better detect your fitness regiment, the battery life lasts longer (even if GPS is enabled for longer activities), and the device can give more information about mile pace when running.

(Credit: Apple)

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  1. The new Apple Watch Series 4's ECG heart monitoring app is now live for the US.
  2. With just a few taps, users can take a 30-second ECG and export it as a PDF to easily share with a doctor.

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Shelby is an Associate Writer for CNET's Download.com. She served as Editor in Chief for the Louisville Cardinal newspaper at the University of Louisville. She interned as Creative Non-Fiction Editor for Miracle Monocle literary magazine. Her work appears in Glass Mountain Magazine, Bookends Review, Soundings East, and on Louisville.com. Her cat, Puck, is the best cat ever.