#371 My Apple Watch Detected AFib

My Apple Watch Detected AFib

When Mick bought the first FDA-approved EKG smartwatch, the Apple Watch 4, he didn’t do it for the atrial fibrillation (AFib) and EKG features. He just happened to be a really big fan of Apple products. Smartwatches, including the Apple Watch, commonly use the term ‘ECG’ to refer to ‘EKG,’ both of which mean the same thing.

But thank goodness he was, because in the year before he made that purchase, he had noticed that occasionally it was getting harder to exercise and that he felt tired more often. “I just figured that was just what happens when you get older,” he said. “You have some good days and some bad days, right?”

He did think the smartwatch would help him get back in shape through apps that track exercise and steps. But soon after his purchase, his Apple Watch detected AFib. Although he ignored the first few AFib alerts, Mick eventually reached out to his family doctor, who referred him to a local cardiologist. After an EKG and a stress test, the doctor confirmed that Mick had AFib, prescribed the usual meds consisting of a beta-blocker (metoprolol) to slow his heart down and a blood thinner (Eliquis), and sent him on his way.

The AFib Alerts Kept Coming

But Mick’s Apple Watch detected AFib again and again. “And this time I took it more serious,” he said. “The watch was right the first time—it alerted me to AFib and, sure enough, that’s what the doctor confirmed. So now that it was basically saying that the meds weren’t keeping my heart in rhythm any more than it had been before, I was pretty concerned.”

When Mick returned to his local cardiologist with that information in hand, the doctor agreed it was time to get him in to see us.

Could an Apple Watch Save Your Life?

Just think about this: because Mick’s symptoms were so subtle and intermittent, he would likely have not known he had atrial fibrillation for many months, if not years, if he had not had the watch. Fortunately, with his early smartwatch diagnosis, his AFib was easily treated—long before any significant problems developed. So, it isn’t hyperbole to say that Mick’s watch might have saved him from a devastating AFib stroke.

How Reliable are AFib Symptoms?

Now, some people don’t think they need an AFib-detecting watch. They think they can feel every episode. Studies clearly show, however, that many people with AFib experience episodes that they can’t feel. What’s more, waiting until an episode is strong enough that it can be felt may mean you’ve waited too long. Complicating matters even further, studies also show that symptoms perceived to be AFib are something else at least 50 percent of the time. And, to make things even more challenging, if you’ve have had an AFib ablation, many of the cardiac nerves that once helped you perceive your AFib symptoms may have also been treated as part of the procedure, so all bets are off as to whether your symptoms will still reliably flag future episodes of AFib.

What Other Arrhythmias Can Fool an Apple Watch?

Unfortunately, the Apple Watch’s ability to detect AFib is far from perfect. In fact, at least 50% of the EKGs patients send us for AFib analysis turn out not to be AFib at all!

This is why it’s crucial not only to rely on your Apple Watch for detecting AFib but also to recognize when it might be a false alarm. To do that, you’ll need some basic EKG reading skills, as the technology in these devices still has a long way to go before you can fully trust their interpretations. Of course, you’ll always want to show these EKGs to your physician to verify the correct diagnosis. .

AFib typically presents as a fast and irregular rhythm—so irregular that you won’t be able to detect a consistent pattern in the beats. However, that’s not always the case. We’ve seen numerous instances where people with AFib have a very slow heart rate, so don’t dismiss the possibility of AFib just because your heart isn’t racing.

On the other hand, atrial flutter is usually fast and regular, with a consistent, patterned beat. And this is why atrial flutter often triggers a high heart rate alert from the Apple Watch. Yet, as with AFib, there are exceptions. Atrial flutter can sometimes occur with a slower heart rate or even appear irregular, though this is less common.

Premature beats—such as premature atrial contractions (PACs) or premature ventricular contractions (PVCs)—usually result in a normal or slightly slower heart rate but with a detectable pattern to the irregularity. For example, you might notice a few normal beats followed by one that’s out of sync.

Lastly, motion artifact is another common cause of false alarm AFib detections on the Apple Watch. If both your elbows and hands aren’t resting firmly on a flat surface, even minor movements can create jagged EKG lines, misleading the device. And for individuals with significant tremors, the motion artifact might make it impossible to obtain an accurate reading.

What Does an Inconclusive Reading Mean?

Besides smartwatches often not being able to tell the difference between excessive movement while taking the EKG, atrial fibrillation, and sinus rhythm with a lot of premature beats, our smartwatch-wearing patients are also bothered when their watch can’t “figure out” their rhythm. When this happens, the watch calls the EKG “inconclusive.” Usually, inconclusive means that you were moving too much during the EKG and this movement made your EKG uninterpretable. However, it could also mean that your heart rate is too high or too low, that there are too many premature beats, or your heart is in some other rhythm.

What Do All the “Squiggles” on the ECG Mean?

With all that in mind, let’s look at some charts, starting with with what normal sinus rhythm looks like.

On this smartwatch-recorded EKG, the watch correctly diagnosed its owner as being in normal sinus rhythm at ninety beats per minute. This is a high-quality recording; the watch’s owner was sitting perfectly still when it was taken. Each beat is perfectly timed and the heart rate is within the normal range.

My Apple Watch Detected AFib: Question 1

Let’s put your skills to the test: Can you interpret an Apple Watch EKG? Did the watch correctly diagnose this individual with AFib? What specific features of the EKG or heart rate support your conclusion? The answers are provided below—take a look after making your assessment!

In this tracing, you’ll notice that this individual’s resting heart rate is elevated at 113 bpm, and that the distance between every beat is completely different. We call this being “irregularly irregular” and, once again, the watch has made the correct diagnosis: She is in AFib.

My Apple Watch Detected AFib: Question 2

There are some limitations to these Apple Watch devices, of course. Take this tracing below for instance. In this case, the user knew she was out of rhythm. Indeed, her resting heart rate was 143 bpm and her pulse was very irregular. However, because her resting heart rate is above 120 bpm, this watch wouldn’t even venture a “guess” as to whether she was in AFib. Needless to say, she was rather frustrated with her Apple Watch. What’s your diagnosis?

As an astute observer of AFib, you can easily make the call. Once again, we see that the rhythm is fast and the distance between every heartbeat is “irregularly irregular.”  This is another episode of AFib.

My Apple Watch Detected AFib: Question 3

Now, how about a  challenge? What’s your diagnosis on this ECG? With all of the jagged lines on this ECG do you agree with the Apple Watch’s diagnosis?

In this case, the rhythm is mostly regular. The heart rate is not elevated. But there are lots of jagged lines between each heartbeat. What’s happening?

Well, in this situation, the watch is correct. This is normal sinus rhythm. The distance between each beat is mostly constant. But what are tall those jagged likes? Those are from “movement artifact,” which happens when the electrodes aren’t making stable contact with the skin.

My Apple Watch Detected AFib: Question 4

Are you up for another challenge? Here is a common EKG that our patients send to us, known as the “high heart rate” EKG. Any idea what is going on with this patient?

The patient is clearly at rest, given the very clean EKG tracing with no jagged lines from movement, yet the heart rate is 123 beats per minute. In this case, the rhythm was atrial flutter, which often presents with a fast heart rate and a very regular rhythm. However, it could just as easily have been another type of arrhythmia, such as SVT. If you have been diagnosed with AFib, odds are that if you get the high heart rate alert from your smartwatch, the diagnosis is atrial flutter.

My Apple Watch Detected AFib: Question 5

Some of our patients have even been able to catch EKGs like this one. The Apple Watch computer in this ECG below is saying “sinus rhythm” and “this ECG does not show signs of atrial fibrillation” but is this really the case? How would you interpret the ECG below?

Even though the computer called this EKG “sinus rhythm” it missed the fast atrial fibrillation at the beginning of the EKG. The other interesting thing about this EKG is that after the rapid AFib at the beginning of the EKG terminated there is a long pause with no heart beat until sinus rhythm kicked in. If these pauses last too long when AFib terminates it can cause people to pass out.

Apple Watch versus Other Home ECG Devices

Now, all smartwatches are not created equal. Technology will change over time. But if you have AFib, or if you are at risk of developing AFib, there’s really no better investment than a watch that will, at a minimum, be able to detect AFib with reliability and record an EKG. Watches that just record your heart rate, or try to record a “artificial EKG” through the light sensor based on the regularity of your pulse on your smartphone, are not as accurate for detecting AFib.

And watches aren’t the only tech that can help you track your AFib. Many of our patients use less expensive Bluetooth-enabled electrodes that work with many different types of smartphones. Still others use a pulse oximeter, stethoscope and blood pressure machine with built in rhythm checks. Outside of an implanted heart monitor, though, we have found that for many of our patients, wearing a watch is the most reliable method to keep a constant vigil for AFib events.

Now, these devices are are not continuous monitors, so they can miss short events. In most cases, what you get from a smartwatch is a “fingerprint” of what your heart rate is supposed to look like. Then, by tracking the graphs each day, you can quickly identify when things change. Even still, your doctor may not think that the symptoms you describe are from AFib unless you provide a real EKG for them to review. And that’s not a bad thing; you don’t want your doctor prescribing new medications or ordering up procedures unless they are 100 percent certain that you are indeed experiencing AFib.

But just because smartwatches aren’t perfect doesn’t mean they can’t be a tremendously important tool for catching early incidents of AFib, tracking incidents over time, and alerting pill-in-the-pocket patients to potential incidents that might warrant the use of medications.

Can Smartwatches Help You Beat AFib?

If we only use smartwatches as AFib warning or EKG devices, we’re missing out on their full potential. These devices often collect detailed daily heart rhythm data that can be easily shared with your cardiologist. This data is incredibly valuable, offering insights into how your daily, weekly, and monthly habits affect your heart rhythm.

In the near future, smartwatches will likely evolve to accurately monitor blood pressure and other biomarkers, further enhancing their role in disease prevention and management. For now, however, they already offer impressive capabilities: tracking your sleep, monitoring for sleep apnea, measuring exercise, and even assessing stress levels.

In our practice, we strongly encourage all patients to invest in a smartwatch. For those who cannot afford one, we recommend more affordable alternatives, such as the Kardia Mobile device, to monitor heart rhythms. If your goal is to put AFib into remission, having access to even basic home ECG monitoring technology is essential.

Disclaimer (Never Trust the Computer’s Diagnosis or Your Own ECG Interpretation)

The information in this article is for educational purposes only and should not be considered medical advice. While wearable devices and home ECG monitors can provide valuable insights into your heart health, they are not a substitute for professional medical evaluation. Do not attempt to independently interpret your ECG results or use them to make medical decisions without consulting your physician. Additionally, be cautious of the computer-generated interpretations provided by home ECG devices, as these automated diagnoses are often inaccurate. Always share your ECG data and any concerns with your healthcare provider to ensure accurate diagnosis and appropriate treatment.

 

 

 

 

 

 

 

Disclaimer Policy: This website is intended to give general information and does not provide medical advice. This website does not create a doctor-patient relationship between you and Dr. John Day. If you have a medical problem, immediately contact your healthcare provider. Information on this website is not intended to diagnose or treat any condition. Dr. John Day is not responsible for any losses, damages or claims that may result from your medical decisions.

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