The Apple Watch ECG has detected something strange about my heart rhythm – CNET


When I started testing the new EKG feature on the Apple Watch Series 4 – available Thursday through the free version Watch OS 5.1.2 software update – the last thing I expected was to find something abnormal with my heart rhythm. But that's exactly what happened when I cross-referenced Watch's readings with EKG equipment for medical use at the doctor's office.

"We see on your Apple watching the same heartbeat that we see on the EKG," said Dr. Gregory Marcus, professor of medicine and cardiac electrophysiologist at UCSF Medical Center while sitting on the hospital bed with cables attached to my body and an Apple Watch Series 4 to my wrist.


The results of Apple Watch EKG showed the same irregular rhythm of the doctor's ECG.

James Martin / CNET

"These first few beats are very common … but they can lead to long-term problems, so we should talk a little more," he added.

Heart rate monitoring has always been an important part of Apple Watch and fitness trackers in general. But until now, it has been mainly used for activity tracking and calorie counting.

By upgrading to Watch OS 5.1.2, heart rate will play a bigger role on Apple Watch as soon as we have access to two new features that FDA has eliminated that Apple announced in its September keynote. There is an abnormal heart rhythm alarm for all Apple Watch, except the first-generation model, and an exclusive Series 4 electrocardiogram (ECG or ECG). Both can help warn against potentially dangerous cardiac conditions For the life.

Now playing:
Watch this:

We have tested the Apple Watch EKG against a hospital ECG


Measurement of heart rate

Heart rate monitoring is not new for wearable devices. Smartwatch and fitness trackers have used LEDs and optical sensors on the back for years to measure changes in blood flow beneath the surface of the skin, or the wrist. When the heart beats, more blood is pumped into the blood vessels, absorbing more light. Among the beats when there is less blood, more light is reflected in the receivers of the watch.

Set your irregular heart rate notification from the Health app on Apple Watch Series 1 and beyond.


In 2017, Apple Watch became proactive about how it used heart rate information by adding high heart rate notifications to the watch, which let users know when their heart has risen above a certain level and subsequently have added low heart rate notifications. These notifications had already been help users detect serious conditions.

But the heart rate measures only the beats per minute, or the frequency of the heartbeat over time and not the patterns between each beat known as heart rhythm.

"You can have a regular rhythm that is very fast or too slow … And in the same way, you can have an irregular rhythm that is of a normal frequency, which is too fast or too slow," said Dr. Marcus.

With the new irregular rhythm notification, Apple Watch uses the optical sensor to measure heart rhythm and alert users when it detects an irregular pattern that may be atrial fibrillation (AFib), a type of arrhythmia that can increase the risk of stroke and other serious cardiac complications. This feature only works for adults over the age of 22 and will not help if you have already been diagnosed with atrial fibrillation.

EKG on Apple Watch

To make a definitive diagnosis, a doctor needs more information than the impulse can provide.

"Sometimes those beats are so precocious that the heart has not had enough time to fill, even if electrically there can be an anticipated beating that is happening," said Dr. Marcus. "We would like to have an electrical confirmation of a diagnosis of atrial fibrillation before deciding to act on it and not to base it in general, just on the wrist record," he added.

This is where the ECG comes into play. An ECG uses electrodes to measure the electrical activity of the heart. A hospital electrocardiogram is generally made up of 10 electrodes placed on different parts of the body. While the Apple Watch Series 4 has two: an electrode on the back crystal and an electrode on the digital crown.

"This 12-lead ECG shows what is happening electrically in the heart from 12 different points of view, or 12 different directions, while Apple Watch gives you the same electrical activity, but in only one direction," explained Dr . Marcus.

Apple Watch uses electrodes on the back and on the digital crown combined with the ECG app.

James Martin / CNET

While looking at his monitor, I opened the new ECG app (Apple uses the abbreviation ECG, while doctors generally say ECG) on the Apple Watch Series 4 to take my first EKG. I put my finger on the digital crown and waited for the screen to be counted for 30 seconds. The Apple Watch classifies your heart rhythm as AFib, sinus or inconclusive rhythm. My result: inconclusive.

The notification on Apple Watch also said that I should contact my doctor if I did not feel well or if I continued to get the same result. Users can share these results in pdf format with their doctors, but fortunately my doctor has been standing next to me.

The ECG on the Apple Watch coincided directly with the ECK results of the hospital that Dr. Marcus had printed. There were early intermittent beats coming from the lower chamber of my heart.

"This would be really useful for screening this or for having the first understanding that you have these first heartbeats," said Dr. Marcus. "What's missing in the single Apple Watch lead is the information that specifically tells us where exactly it comes from."

The results of Apple Watch on the iPhone compared to the results of 12-lead EKG on the card.

James Martin / CNET

More information equals faster results

Dr. Marcus says I probably will not die because of what he found on my ECG, but he wants to see me follow my heartbeat, something I probably would not have discovered without this kind of test. And for people with more severe heart conditions, this could help doctors make a faster diagnosis and allow them to treat the problem first.

"Some people feel it when they have atrial fibrillation, but many people do not, so it's this hope that we could discover those people who otherwise did not know they had atrial fibrillation," said Dr. Marcus.

Apple Watch is the only consumer-facing device with an integrated ECG. But there are other devices such as the FDA of Alivecor who authorized KardiaMobile and KardiaBand for the Apple Watch that give users access to an ECG outside the doctors' office. Apple also looks at competitors like Garmin and Fitbit improve heart rate monitoring as more technology companies focus on health care as a way to give new life to wearables.

"The downside is that we recognize that there is a risk of false positive results that could lead to an" undue anxiety ", said Dr. Marcus.

Irregular heart rate notification is already available on all Apple Watch from Series 1 and can be configured in the Heart section of the Watch app. The EKG app is only available on the Apple Watch Series 4 and is only available in the United States, although Apple expects to obtain regulatory approval for this feature in other countries later.

Read the next: How to buy a smartwatch or a fitness tracker

Read also: The best smartwatch and fitness tracker of 2018 for the holidays


Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.