ECG Readings From the Apple Watch? This Doctor Is Leery

Hansa Bhargava, MD


September 14, 2018

The Apple Watch Gets 'Medical'

This week, Apple unveiled the next generation of Apple Watch, among other products, and seemed to take a "bite" out of healthcare.

Hansa Bhargava, MD

Its new Apple watch (Series 4) not only has the capability of detecting a fall by its motion sensor, but it also can monitor heart rates to detect atrial fibrillation and slowing rates. It can generate an ECG tracing similar to that of a single-lead electrocardiograph.

What does this mean? For many people, having a wearable device that tracks heart rate, respiration, steps, and activity is compelling; many of us like to know our numbers in regard to how our bodies are doing when running or swimming, or in general.

But the capacity to track a fall, and to even contact emergency medical services (EMS) if the device does not detect motion for 60 seconds after a fall, is definitely an advance and steps out of the sphere of "wellness" data. It is actually taking information and acting upon it. This can be very helpful, especially with the aging population and because there are many falls that occur for which you can't just call EMS.

So, What's the Problem?

Regarding tracking arrhythmias and the ability to do a one-lead ECG, I'm interested but a little more reserved. I can certainly see the applications for the approximately 6.1 million people who have been diagnosed with atrial fibrillation, according to the Centers for Disease Control and Prevention. This or other wearables that have been cleared by the US Food and Drug Administration, such as KardiaBand—a mobile ECG for the Apple Watch—could certainly monitor episodes.

But here's what I worry about: the false sense of security that a person could have.

Being able to do a one-lead ECG is definitely interesting, but does it always help? Here's a scenario. A 40-year-old runner starts feeling dizzy, lightheaded, and has chest pain. He worries but remembers that there is an ECG function on his watch. He proceeds to do the ECG which then reads "normal." Because of this he decides to continue to run.

What he doesn't know is that this is only a one-lead ECG, and even though it seems normal, it is an isolated data point; more information is needed to diagnose what is going on. What if he is having angina? In fact, 30% of cardiovascular events happen to people under the age of 65. One lead on an ECG could certainly miss this; in fact, even a 12-lead ECG, if the only isolated data point, could miss this.

In medical training we are taught two very important things: to look at multiple data points and to look at and listen to the patient. The way a patient looks and feels is key. Symptoms, in this case dizziness and chest pain, do matter in the differential diagnosis. The history matters, as does the physical exam. Typically, this type of patient presenting with chest pain not only would get a 12-lead ECG in the emergency department but also would need other data points, including bloodwork, consultation by a specialist, and, of course, a history and physical exam.

If all of these are negative but there is still a high degree of suspicion, the patient may be observed for 24 hours and get a Holter monitor, a 24-hour ECG, to rule out a cardiac event.

This is not to say that this technology is insignificant or unhelpful. For the older patient, the diagnosed patient, and the undiagnosed patient who happens to have their first arrhythmia detected by the Apple Watch, it has many benefits.

And, of course, for falls. If the accuracy is high, the motion sensor could help notify EMS. Heart rate and ECG data combined with a doctor's visit or other information could be key in early diagnosis for arrhythmias. But just like with anything else, we need to take it with a grain of salt.

In this case, the grain is patient education. At the end of the day, if you don't feel good, call your physician. Period.


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