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Is the New Apple Watch's ECG Feature Legit?

Illustration for article titled Is the New Apple Watchs ECG Feature Legit?em/em

Many of the products announced during Apple’s annual iPhone event today are sure to get people excited, but it’s the newest, fourth iteration of the Apple Watch that could have grand public health implications.


The Apple Watch, already marketed as a heart rate monitor, will now have sensors capable of taking someone’s electrocardiogram (ECG or EKG); it will also be able to warn the user if they possibly have a serious heart condition called atrial fibrillation (also called AFib or AF).

But while these claims might look like the sort of grandiose boast made by any company marketing their wearable technology, Apple is seemingly putting their money where their mouth is. Not only has its watch’s new features earned the blessing of the American Heart Association, they’ve even been cleared by the Food and Drug Administration as a new type of medical device.


“Capturing meaningful data about someone’s heart in real time is changing the way we practice medicine,” said Ivor Benjamin, president of the American Heart Association, on the stage immediately following Apple COO Jeff Williams’ announcement of the watch.

ECGs are essentially the gold standard of heart rate measurement. In a doctor’s office, electrodes placed near the heart record the electrical activity of your beating heart, allowing for an up-to-the-moment measurement.

The redesigned Apple Watch, by comparison, has an electrode embedded in the back as well as in its crown. To use the app and obtain a reading, you place your finger on the crown for thirty seconds. If your heartbeat is normal, the reading will show up as a sinus rhythm. But if it’s not, the watch will notify you that you might have atrial fibrillation, otherwise known as an irregular, usually too rapid heartbeat that can cause poor blood flow and increase the risk of other cardiovascular conditions such as heart attack and stroke. The data from these readings, according to Apple, will be encrypted, allowing users to only share them willingly via a PDF, including with their doctors.

Other new features of the watch include being able to notify users if their heart rate is too low and being able to call for emergency help if you’ve fallen, similar to existing medical alert systems like Lifealert. It even has a bigger screen.


After Apple announced that the watch’s ECG feature, as well as its ability to detect atrial fibrillation, had been cleared by the FDA, the agency put out its own statement.

“The FDA worked closely with the company as they developed and tested these software products, which may help millions of users identify health concerns more quickly,” said FDA chief Scott Gottlieb.


Despite the company’s claims, the Apple Watch actually isn’t the first piece of wearable technology to have ECG capability. Last November, a sensor attachment for the Apple Watch with similar features, the Kardiaband, was cleared by the FDA as well. And the company behind this attachment, AliveCor, previously had its ECG monitor technology cleared for over-the-counter use by the FDA. But the technologies utilized in the watch, according to the official summary documents detailing their clearance, are unique enough to merit them both being classified as de novo, meaning novel, medical devices.

The potential for these wearables is certainly high. It’s estimated that anywhere from 2.7–6.1 million Americans have atrial fibrillation, with around 750,000 people being sent to the emergency room annually as a result. And part of what makes the condition so dangerous is that, oftentimes, people can have it and show no visible symptoms.


But we should also be a little cautious about the hype surrounding these features. As even the FDA points out in its summary document, the ECG app isn’t meant to be used in people younger than 22, nor is it recommended for people with other known heart conditions that can disturb your heart rhythm.

In the summary document of the second feature that notifies people of a possible atrial fibrillation, the agency also points out that the app “is not intended to provide a notification on every episode of irregular rhythm suggestive of AFib and the absence of a notification is not intended to indicate no disease process is present.”


That’s a pretty important caveat!

Other wearables such as the Fitbit have endured their share of criticism over their heart rate technology becoming much less accurate when people are actually moving. And while normal ECGs are better at handling movement than the light-based sensors found in other activity trackers, it’s worth studying if their accuracy can degrade when miniaturized into a watch. And aside from not catching every case of AFib, there’s also the worry that users will freak out and rush to their doctors with faulty false positives in hand.


All these concerns shouldn’t detract from the importance of Apple’s announcement. If nothing else, the company’s decision to gain FDA clearance is a meaningful step in someday validating the usefulness of these devices to better our lives (provided you can afford the base $399 cost, of course)—a step that other device manufacturers might need to emulate to stay competitive with Apple. Just don’t expect any miracles from your watch.

The Apple Watch Series 4 is set to go on sale in the U.S. on Friday.


Science writer at Gizmodo and pug aficionado elsewhere

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As an ECG tech, this thing is really only good for 1 thing: detecting irregular heart rate. There’s a reason that they stated it only uses 1 lead and that’s because it’s exactly what it is, a single circuit through the body that measures the heart’s electrical impulse. However, to get an actual accurate reading, you need significantly more than that, preferably at least 5 leads for a normal continuous monitor, Because the electrical impulses of the heart travel in different directions, and different ischemia can be at locations invisible to less leads than that. This isn’t going to recognize 1st or 2nd degree type 1 heart block, ventricular arrhythmias that have a regular rate, or anything of that sort. It will only detect whether you have an irregular rate and possibly some atrial abnormalities. It’s a good first step, but I don’t think people should use it in place of an actual 5 or 12 lead ECG.