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Using the ECG app in watchOS 5.1.2.

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watchOS 5.1.2 Brings ECG to the Apple Watch Series 4

The Apple Watch was the surprise star of Apple’s September press event (see “Apple Watch Series 4: Bigger Screens, New Faces, and Enhanced Health Monitoring,” 12 September 2018), partly because of a health-monitoring feature no one saw coming: electrocardiogram (ECG) reading.

Apple announced that users of the new Apple Watch Series 4 would be able to use an ECG app along with electrodes built into the watch to determine if their hearts were beating normally or were showing signs of atrial fibrillation (AFib)—a condition that can lead to major health complications such as strokes. The company also unveiled a passive-monitoring feature to detect irregular heart rhythms and extended this capability to most older Apple Watch models.

These features were said to cement the Apple Watch’s preeminence in the smartwatch market, and help establish it as a leading health-monitoring device with a likelihood of saving lives (see Rich Mogull’s TidBITS article “I’m a Paramedic: Here’s How the Apple Watch Series 4 Will and Won’t Save Lives,” 3 October 2018).

However, the heart-monitoring features didn’t ship with the Apple Watch Series 4, and Apple promised them in a future update. That update is here in the form of watchOS 5.1.2. To install it, open the Watch app on your iPhone, go to My Watch > General > Software Update, and tap Download and Install. The update sizes vary—we saw 132 MB on an Apple Watch Series 2 and 176 MB on a Series 3. Installation may take longer than you think it should—we recommend updating while you sleep. watchOS 5.1.2 release notes.

The ECG app and irregular heart rhythm detection are currently available only in the United States, Puerto Rico, Guam, and US Virgin Islands. Apple will have to apply for and receive approval from medical regulatory agencies in other countries before it can make the features more widely available.

Setting Up and Using the ECG App

Apple claims that the Apple Watch Series 4 along with the new ECG app in watchOS 5.1.2 marks “the first direct-to-consumer product” enabling average people to take an electrocardiogram entirely on their own. That’s patently untrue; AliveCor’s KardiaBand provided exactly these features a year ago—a family member of one of the TidBITS staff used it over the last year after undergoing heart valve repair surgery.

Regardless, electrodes built into the Apple Watch Series 4’s back crystal and Digital Crown work in tandem with the ECG app to provide a heart reading. When the user touches the Digital Crown with a fingertip, an electrical circuit is completed and heart signals are measured, which takes about 30 seconds.

Before you can use the ECG feature, you need to do a bit of preparation following the installation of watchOS 5.1.2. Press the Digital Crown to find the ECG app, which is mixed in with all the other watch apps, and tap it to open. It then prompts you to open the Health app on your iPhone.

The first step is entering your date of birth. Then, after a bit of a crash course on ECG readings, and a few warnings about what the ECG app can’t do—no heart-attack, blood-clot or stroke detection, for instance—you’re ready to take your first ECG.

Apple's ECG walkthrough.

For me, this worked without a hitch. As instructed, I made sure my watch fit snugly on my left wrist, rested my arms on a flat surface, and held my right index fingertip to the Digital Crown. The ECG app then counted down from 30.

According to the app, I checked out fine. My “sinus rhythm” indicated that the ECG didn’t show atrial fibrillation and that my heart was beating in a uniform pattern.

Results are stored in the iPhone’s Health app, and you can share the data with your doctor as a PDF document. On your iPhone, go to Health > Heart, and under This Week, tap Electrocardiogram (ECG). Tap the chart at the top. Then look for Export a PDF for Your Doctor, and use the standard Share function to email the PDF or send it out by other means.

Here’s what my exported PDF looks like:What an ECG PDF looks like.

Is the ECG App Any Good?

I’m no judge of how well, in the medical sense, the ECG app works. My TidBITS colleague Rich Mogull is a paramedic, though, and has a bit more insight.

Rich tweeted a lot about the topic after installing the watchOS 5.1.2 update. Among his observations:

  • Results contain more data for doctors than he expected. In fact, he thinks they could get insight into other kinds of heart arrhythmias, but Apple specifically says the ECG app is not designed to do that.
  • He echoes Apple’s warning that the Apple Watch Series 4 is inadequate for detecting heart attacks, which requires more sophisticated equipment.
  • He warns that all ECGs are prone to electrical interference from movement. “You definitely want your hands resting on something,” he said.

All that aside, the ECG app successfully detected a family member’s already-known case of AFib, so Rich can confirm that the feature works.

How AFib looks in the ECG app.

Irregular Heart Rhythm Monitoring

Separate from but related to watchOS 5.1.2’s newfound ECG support is its new capability to monitor for irregular heart rhythms. Unlike the ECG readings, irregular heart rhythm monitoring occurs in the background without the user having to do anything.

An alert from this feature would presumably nudge an Apple Watch Series 4 user into taking an ECG reading, which could point to AFib. According to Apple, a rhythm notification means the Apple Watch has “identified an irregular heart rhythm that may be AFib and confirmed it with multiple readings.”

Good news for those with older Apple Watch models: the irregular-rhythm monitoring is available on the Apple Series 1, 2, and 3. The original Apple Watch is left out, though.

To set up this feature, on your iPhone running iOS 12.1.1, go to Watch > Health > Heart and enable Irregular Rhythm Notifications.

Other Features of watchOS 5.1.2

The watchOS 5.1.2 update is largely focused on the ECG feature, but it has a handful of new features unrelated to health monitoring:

  • Direct access to supported movie tickets, coupons, and rewards cards in Wallet when tapped to a contactless reader
  • Notifications and animated celebrations when you achieve daily maximum points in a day during an Activity competition
  • New Infograph complications for Find My Friends, Home, Mail, Maps, Messages, News, Phone, and Remote
  • Lets you manage your availability for Walkie-Talkie conversations from Control Center—tap the new Walkie Talkie The Walkie Talkie button. button
  • 12 security fixes

As is often the case with watchOS, we see no particular reason to delay the upgrade past the requisite several days to make sure it isn’t causing problems. The new features are welcome, have no apparent downsides, and enable the much-anticipated hardware capabilities Apple promised for the Apple Watch Series 4 and older models with watchOS 5’s initial release.

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