The new heart-monitoring capabilities on the Apple Watch aren’t all that impressive

An impressive timepiece, but not a health care disruptor.
An impressive timepiece, but not a health care disruptor.
Image: AP Photo/Marcio Jose Sanchez
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When Apple unveiled the new Apple Watch Series 4 yesterday (Sept. 12), the device received a lot of attention for its health-monitoring capabilities. Specifically, those that keep an eye on its wearer’s heart.

Unlike previous versions, this watch comes with an electrocardiogram (ECG) monitor, which has been cleared by the US Food and Drug Administration (FDA) to monitor a user’s heart’s electrical activity at any given time. It can observe a user’s heart rate, as well as atypical beating patterns. The first company to receive FDA clearance for something similar was AliveCor, which used a smartphone app and a small monitor to provide users with an ECG. (AliveCor also partnered with Apple to make an Apple Watch wristband that could carry out the same function.) Apple’s newest watch, which will go on sale later this month, is capable of conducting its own ECGs, and sending alerts to its wearer if their heart rate seems too low, or if it detects a specific kind of irregular heart rate tied to a condition called atrial fibrillation, or AFib for short.

But these capabilities don’t mean much.

An ECG is used by a physician to see how the electrical system of your heart is working, Andrew Moore, an emergency department physician at the Oregon Health and Science University, told Quartz. 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.

The new Apple Watch, however, has the equivalent of one lead on your wrist, the company’s website says. “The tech that Apple is working with is very rudimentary compared to what we’d do for someone in a hospital or health care setting,” Moore said. Although the watch can detect changes in the patterns of a person’s heart rate, these changes really only show a user if she has a heart rate that is too fast, too slow, or beating irregularly—signifying AFib. The watch won’t necessarily give the full picture a doctor would need to diagnose a medical issue.

To be fair, AFib is a serious condition. It occurs when the atria—the top two chambers of the heart—beat rapidly, up to a quiver of 300 beats per minute (compared to the normal resting rate of around 60). “You don’t get that full squeeze [from the heart] so you can form blood clots,” Moore says. If the heart shoots these clots out as it pumps blood, they can cause strokes. The US Centers for Disease Control estimates that between 2.7 and 6.1 million people in the US have AFib.

While the watch can legally be marketed to say that it’s able to detect these changes in heart rate and alert the user or her physician—if she so chooses—this doesn’t mean it’ll be nearly as good as an actual medical diagnosis. Technically, the FDA has “cleared” these capabilities. This status is given to medical devices that the agency deems to be of low to moderate risk to the general public—high-risk devices, like pacemakers, must go through more thorough testing. In this case, the risks users encounter from the Apple Watch would be a failure to recognize AFib, or a heart rate that was too fast or too slow. While these conditions could be serious, they’re not as likely to be fatal as something like a stopped heart due to a faulty pacemaker.

Apple got two FDA clearances through a “de novo” pathway, meaning it had to use data to show that its device worked, and that it was safe. For the ECG clearance, the FDA reviewed a study conducted by Apple and Stanford University in California. This study, called the Apple Heart Study included 588 individuals, half of whom had AFib and the other half of whom were healthy. The app was able to identify over 98% of the patients who had AFib, and over 99% of patients that had healthy heart rates. Cardiologists were able to read 90% of the total readings, although about 10% of them were unreadable.

For the irregular heart-rate notification clearance, the FDA reviewed data from a subset of the Apple Heart Study, which included 226 participants who had been flagged as having AFib. These patients were then monitored on both the app and an ambulatory monitor—what you’d receive in a hospital—for six days. In about 40% of the cases, the ambulatory monitor picked up that they had experienced AFib. When patients’ watches flagged AFib during the monitoring period, 78.9% of the time the ambulatory monitor concluded the same thing.

This kind of testing isn’t nearly as rigorous as some of the testing for new drugs, and Apple’s sample sizes were relatively small. The last stage of clinical trials for new drugs, for example, can include thousands of patients. It’s still a step above things like tongue depressors, which the FDA classifies as some of the more low-risk medical devices on the market: Anything in this category may not have to go through any testing at all, although they could be subject to regulation once they’re on the market. (The watch is considered a “Class II” risk device by the FDA, whereas a tongue depressor is a Class I, and pacemakers are Class III.)

In its approval letters (pdf), the FDA notified Apple of the risks of inaccurate readings, and has mandated that Apple label those risks, and warn users about when the watch may not work. It also stated that the watch is not a substitute for actual medical care, and that patients should not make any medical decisions based on their readings—they need to have them checked by an actual doctor.

“The ECG thing is a little bit overhyped in terms of what it will really provide,” Moore says. 

There isn’t currently anything on Apple’s website to suggest that the Apple Watch complies with the US Health Insurance Portability and Accountability Act (HIPAA), which ensures the privacy of medical data shared between a patient and anyone else, and Apple wasn’t immediately available to comment on its compliance. According to its website, users will be able to share information with their doctors in real time about their heartbeat patterns, presumably through a forthcoming ECG app for the iPhone. Past heart-rate data will be stored in the Health app, alongside data on sleep, activity, and nutrition, should you choose to log it.

The additional heart-health functions on the Apple Watch do have the potential to be a step in the right direction. They may well prompt someone with an irregular heartbeat to talk to their physicians about what might be going on, and could stop a more dangerous medical condition before it starts. But it’s possible that the watch flags false-positives—incorrectly stating it’s caught something—causing a user to panic that they have a potentially serious health issue when they do not. Either way, users will still have to get confirmation of their heart’s activity from an actual human doctor and not their jewelry.

But there was one aspect of the new Apple Watch that is truly promising: its ability to notice when its wearer has fallen, and then notify either emergency services or a loved one for help, unless the user tells it not to.

Using an accelerometer, which measures changes in speed, and a gyroscope, which can detect motion along an axis, the latest Apple Watch can pick up trips, slips, and sudden collapses to the ground. This capability makes the watch hugely useful for aging populations, like the baby boomers in the US. Considering that the global population of aging individuals is set to dramatically increase in the coming years, it’s smart for Apple to make devices that can serve them.