Hand and Heart on Apple Watch Series 4’s ECG App

Apple’s latest watch software update upgrades the heart monitoring capabilities of all Apple Watches and finally lights up Series 4’s Electrocardiogram reader

Apple Watch is the Tom Cruise of tech gadgets, always popping up in the news for heroically saving a regular person’s life.

Almost since the Apple Watch launched in 2015, there’ve been stories of the wearable’s built-in heart rate monitor catching irregular heartbeats: A high school senior almost ignores chest and back pain until he noticed that his heart rate was spiking on the Apple Watch. The high school cheerleader and athlete whose Apple Watch alerted her to abnormal spikes and dips in her heart rate and later found out she had a life-threatening kidney condition. The Australian tech journalist whose Apple Watch helped alert him to the fact that his heart was in almost constant atrial fibrillation. There are hundreds (maybe thousands) of stories like these.

This wearable heroism hasn’t gone unnoticed by Apple. Apple CEO Tim Cook often receives emails and letters thanking him. Sometimes he acknowledges them publicly. More importantly, Apple decided to get serious about healthcare, turning the Apple Watch from a best-selling wearable into, with Apple Watch Series 4, an FDA-recognized consumer health device.

In addition to the heart rate sensor on the back, the Apple Watch Series 4 ($399) adds an electrode on the back and another on the digital crown, making it the first-over-the-counter device capable of performing a single-line EKG or electrocardiogram (EKG and ECG are essentially the same thing). However, when Apple debuted the new wearable in September, the watch arrived without software support for either EKGs or irregular heartbeat rhythm notifications.

That changes today. On Wednesday, watchOS 5.1.2 delivers a free software update that will light up both capabilities. Behind them is a year or more of clinical studies designed to prove the Apple Watch’s applicability as a wearable, consumer, medical device.

The Apple Watch App’s new heart monitoring options at left. Setting up the ECG app, center, and what the ECG app cannot do.

A year ago, Apple and Stanford University launched a major heart study to learn if the Apple Watch’s pulse detection could also be used for detect heart rhythm disorders. 400,00 people signed up to participate. While the full results of the study won’t appear until next year, smaller Preclinical Studies showed the Watch and its new ECG App has a 98.3% sensitivity in classifying Atrial Fibrillation and 99.6% specificity in classifiable recordings for normal heart activity known as Sinus Rhythm.

Apple Watch has long has the ability to detect slow heart rates (below 50 bpm) and then, with watchOS 5, high heart rates (above 120 bpm). With this software update however, all Apple Watches going back to Series 1 will be able to detect irregular rhythm, which could be a sign of atrial fibrillation. AFib is when the heart’s two upper chambers (there are four) beat irregularly. This can lead to, among other things, blood clots that could trigger a stroke.

Someone experiencing AFib might feel heart palpitations, fluttering or shortness of breath. AFib symptoms, however, aren’t always so obvious. With the software update, Apple Watch can detect irregular rhythm activity that you might miss and, if you’re active and you turn on notifications in the watch app, it will check for it every two hours.

Unlike the Irregular Rhythm Tracking, ECG is an on-demand feature. You enable it in the Apple Watch and then perform a single-line reading by selecting the ECG app on the watch and holding one finger on the crown for 30 seconds. Apple does not recommend constantly taking ECG readings. Instead, it might be when you feel symptoms or if you just want to make sure you’ve got “sinus rhythm.”

To better understand what all this means, Apple handed me an Apple Watch Series 4 and an iPhone XR, both pre-loaded with the latest iOS (12.1.1) and watchOS software (5.1.2).

My Heart Buddy

It’s important to note that I’ve never been diagnosed with any serious heart issues. I have, like most men my age, undergone a rigorous EKG, where a technician places a dozen or so electrodes on my body for a 360-degree heart function reading. Apple’s EKG capabilities are not intended to match that. Instead, it’s the equivalent of a single line reading, enough to offer an indication of heart issues or a healthy heart reading. It’s not the same as visiting the doctor’s office.

Some of the irregular rhythm readings I never saw.

I had to wonder, as I placed the 44 mm Apple Watch Series 4 on my wrist and paired it with the iPhone XR, what I might learn.

It’s easy to enable to two new heart health management features. I opened the Apple Watch App and selected “Heart.” Even though I’d already entered my age, height and weight in Apple’s Health App, I had to reenter my age while setting up the ECG App. It’s not designed for people younger than 22. In the case of the Irregular Rhythm Notification, I also had to let the app know if I’d ever been diagnosed with atrial fibrillation (I have not).

Setting up the ECG app on the iPhone and, at left, using it for the first time on the right.

For both the ECG App and the Irregular Rhythm Notification, there are multiple screens explaining how they work and exactly what they will and won’t do. It can’t, for instance, detect a heart attack or a stroke. It’s not checking constantly for AFib and, if your watch tells you you’re fine, it doesn’t mean you can stop taking your heart medication.

This extensive on-boarding is how Apple achieved its FDA over-the-counter ratings, a first for a consumer wearable device. It’s actually known as a De Novo (Latin for “anew”) classification, which means that the Apple Watch Series 4 is a novel over-the-counter device that did not require the traditional FDA 510k pre-market approval process.

To be honest, the irregular heart rhythm notifications is a bit of a letdown. It’s like antivirus software, largely forgotten until it pops up to catch a malware attack. I couldn’t make my heart beat irregularly and, as I said, my heart is fine. Still, I wore the watch as often as possible (I couldn’t sleep with it), to give it every opportunity to finds something.

An AFib alert.

The Atrial Fibrillation notification I never received would look on the watch like a heart with the words “Atrial Fibrillation Heart Rate” below it and it would’ve been based not just on one reading, but multiple readings. At this point, it would be up to you to contact your physician. Unlike the Apple Watch Series 4’s built in fall detection, the watch will not automatically contact emergency services if you do not act on the notification. Personally, I’d like to see some threshold where it does.

Unlike the heart rate notifications, the ECG App is, like most apps, something you actively choose to use.

Instead of hiding the ECG app under the Apple Watch’s existing Heart App, there’s a new icon on the watch that looks like a single beat on a heart rate monitor. I selected the app and followed the brief instructions, ensuring the watch was firmly on my wrist so the rear electrode could make contact, and placing my index finger on the crown. What I couldn’t see at that moment was the tiny electrical current making its way from my wrist through my body and heart, down my arm, through my index finger and back to the watch. I held this pose for 30 seconds as the watch counted down, showed my heartbeat in real time, and displayed my current heart rate. At the end of 30 seconds, the watch informed me I had “Sinus Rhythm,” or normal heart function for that reading.

On the phone’s health app was a record of the reading, including a full, single-line EKG strip PDF that I could choose to share with my doctor. When I chose to do so, the iPhone screen presented me with the file, but no other guidance. In the upper righthand corner of the screen was Apple’s familiar share icon. If I clicked that, I could choose to mail, message, print, save to files, etc.

Though it’s not recommended, I proceeded to run this test dozens of times over the next few days. Soon I conscripted my family, running an EKG on my wife and then my 23-year-old son. Everyone got Sinus Rhythm. I had to restrain myself from running around the block and checking my neighbor’s heart health.

I did not have time to sit down with my doctor and go over my unremarkable EKG readouts. Apple’s own studies, though, indicate a high-degree of accuracy for both the ECG App and the Irregular Rhythm Notifications.

The ECG readouts are collected in the Health App (at left), more on what the Apple Watch cannot do and the EKG shareable PDF.

For Apple Watch Series 1 through 4 owners, the Irregular Rhythm Notification promises an important and, maybe, life-saving upgrade to their existing hardware. For those with heart ailments (whether they’re aware of them or not), the Apple Watch Series 4’s ECG App may be all the incentive they need to buy the $399 wearable/consumer healthcare device.

You can bet that those stories of Apple Watch saving lives are only going to increase. Tom Cruise eat your heart out.