Apple Watch Series 4 Features ‘Very Rudimentary’ ECG Technology

As expected, Apple unveiled the latest Apple Watch at its September 12 event. The wearable features a number of health-related updates, including an ECG monitor and a way to detect falls.

Yesterday, Apple announced that the US Food and Drug Administration cleared two new features for the Apple Watch Series 4, explains a new report from Quartz. One is an advanced method of monitoring the heart called an electrocardiogram (ECG), and the other is the Watch’s ability to detect and notify the user of an irregular heart rhythm.

The Apple Watch Series 4 is the first commercial “over the counter” device to gain Food and Drug Administration clearance for taking electrocardiogram readings. The device has electrodes on its sapphire underside and in the digital crown; by touching the digital crown for 30 seconds, you can take an ECG reading anytime.

Once the reading is complete, Apple’s ECG app tells you your heart rate and whether you have a sinus heart rhythm, which is normal, or atrial fibrillation, an irregular heart rhythm. It’s not a replacement for a doctor, but it has FDA approval. It’s accurate enough to be taken seriously, and that’s a huge step for a consumer wearable device. The watch also keeps track of your ECG readings in the Health app, so if you do have some irregular readings, you can export them as a PDF to share with your doctor for further analysis.

The news sounds exciting, but there are some important caveats that limit how useful the new gadget will be.

The FDA clearance letters for both the ECG and irregular rhythm notification functions note that they are not intended to be used by people under the age of 22. The irregular rhythm feature is not intended for people who have previously been diagnosed with atrial fibrillation, which is one of the most common causes of an irregular rhythm.

It’s also important to keep in mind that the Apple Watch Series 4‘s ECG abilities do not replace the ECG monitors that doctors use in a supervised setting. “In a health care facility, a patient would have 12 different stickers, or leads, placed all over her chest and on certain spots on her arm and leg, to give doctors a clear picture of the four chambers of her heart’s movement,” reads the report.

The new Apple Watch, however, has the equivalent of one lead on your wrist. “The tech that Apple is working with is very rudimentary compared to what we’d do for someone in a hospital or healthcare setting,” says Andrew Moore, an emergency department physician at the Oregon Health and Science University.

There is, however, the matter of life-saving potential to consider. If there’s a silver lining to putting electrocardiograms on every Apple Watch wearer’s wrist, it’s that their data could help researchers resolve the uncertainty surrounding ECG screening in seemingly healthy people.