When I first started testing the new ECG feature for the Apple Watch Series 4, which is available on Thursday from the freecarried out. The last thing I expected was to find something abnormal with my heart rhythm. But that's exactly what happened when I compared the measurements in the medical office with medical ECG equipment.
"On your Apple Watch, we see the same early heartbeat that we see on the ECG," Dr. Gregory Marcus, Professor of Medicine and Cardiac Electrophysiologist at UCSF Medical Center, was sitting on the bedside with cables on my body and an Apple Watch Series 4 on my wrist.
"These early beats are very common … but they can cause problems in the long run, so we should talk a little bit more about that," he added.
Heart rate monitoring has always been a big part of the Apple Watch and Fitness tracker in general. However, so far it has been mainly used for.
With the update to Watch OS 5.1.2, heart rate will play a more important role in the Apple Watch as we gain access to the two new FDA-approved features Apple announced in its September keynote address. All Apple watches, except the first-generation model, have an abnormal heart rate alarm and an electrocardiogram (ECG or ECG) available only for the Series 4. Both could help to warn of potentially life-threatening heart problems.
Measuring Heart Rate
Heart rate monitoring is not new to wearables. Smartwatches and fitness trackers have been using LEDs and optical sensors on the back for years to measure changes in blood flow below the skin surface. When the heart beats, more blood is pumped into the blood vessels, which absorbs more light. Between the beats, when less blood is present, more light is reflected in the receiver of the clock.
In 2017, the Apple Watch began its work on heart rate information by adding high-frequency notifications to the clock, informing users when their heart was above a certain level, and later adding low-heart rate notifications. These notifications had already helped.
However, the heart rate measures only beats per minute or the frequency of the heartbeat over time rather than the patterns between beats, which are referred to as heart rhythms.
"You can have a regular rhythm that is very fast or too slow … and you can also have an irregular rhythm that is normal, that is, too fast or too slow," Dr. Marcus.
With the new irregular rhythm notification, the Apple Watch uses the optical sensor to measure the heart rhythm and alert users when they detect an irregular pattern that may be atrial fibrillation (AFib), a type of arrhythmia which may increase the risk of stroke and other serious cardiac complications. This feature is only available for adults over the age of 22 and is not useful if you have already been diagnosed with AFib.
ECG on the Apple Watch
To make a definitive diagnosis, a doctor needs more information than the pulse.
"Sometimes these beats are so early that the heart did not have enough time to fill, even if an electric shock is taking place early," Dr. Marcus. "We want to have electrical confirmation of atrial fibrillation diagnosis before deciding to respond, and not generally, but on the pulse record alone," he added.
This is where the ECG comes into play. An ECG uses electrical electrodes to measure the electrical activity of the heart. A hospital ECG generally consists of 10 electrodes placed at different parts of the body. The Apple Watch Series 4 has two: One electrode on the back crystal and one electrode on the digital crown.
"This 12-lead ECG shows what's going on in the heart from 12 different perspectives or 12 different directions. The Apple Watch gives you the same electrical activity, but only in one direction," Dr. Marcus.
When he looked at his monitor, I opened the new ECG app (Apple uses the abbreviation ECG, whereas doctors usually say ECG) on the Apple Watch Series 4 to record my first ECG. I put my finger on the digital crown and waited for the screen to count down 30 seconds. The Apple Watch classifies your heart rhythm as either AFib, sinus rhythm or as inconclusive. My result: not conclusive.
The Apple Watch notification also said that I should contact my doctor if I am not feeling well or if I continue to get the same result. Users can share these results in PDF with their doctors, but fortunately my doctor was next to me.
The ECG of the Apple Watch coincided directly with the results of the ECG hospital. Marcus had printed. There were intermittent early beats from the lower chamber of my heart.
"This would be really useful to verify or to understand that you have these early heart beats," said Drs. Marcus. "What's missing with the single-lead Apple Watch is the information that tells us exactly where this comes from."
Further information yields faster results
Dr. Marcus says I probably will not die what he found in my ECG, but he wants me to look after my early heartbeat, which I probably would not have caught without this type of test. And for people with more serious heart problems, this could help physicians make a faster diagnosis and treat the problem sooner.
"Some people feel it when they have atrial fibrillation, but many people do not, so there is hope that we could discover people who otherwise did not know they had atrial fibrillation," Dr. Marcus.
The Apple Watch is the only direct device with integrated ECG. But there are also other devices like Alivecor's FDA approval for KardiaMobile and KardiaBand for the Apple Watch that allow users to access an ECG outside the doctor's office. Apple Watch competitors such as Garmin and Fitbit are also working to improve their heart rate monitoring while more tech companiesto bring wearables back to life.
"The downside is that we recognize that there is a risk of false positives that can lead to excessive anxiety," Dr. Marcus.
Irregular heart rhythm notification is already available on all Apple Watches that begin Series 1, and can be set up in the Heart area of the Watch app. The ECG app is only available for the Apple Watch Series 4 and only in the US. However, Apple expects this feature to be later approved by law in other countries.