Study Confirms Apple Watch Can Detect Abnormal Heart Rhythm With 97% Accuracy

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The heart rate monitors built into the Apple Watch and other wearable devices can detect abnormal heart rhythms with 97 percent accuracy, according to a new study conducted by the team behind the Cardiogram app for Apple Watch in conjunction with researchers at the University of California, San Francisco.

More than 139 million heart rate and step count measurements were collected from 9,750 users of the Cardiogram app who also enrolled in the UC San Francisco Health eHeart Study, with the data used to train DeepHeart, Cardiogram's deep neural network.


Once trained, DeepHeart was able to read heart rate data collected by wearables, distinguishing between normal heart rhythm and atrial fibrillation with a 97 percent accuracy rate, both when testing UCSF patients with known heart issues and Cardiogram participants.

At a 97 percent accuracy rate, Cardiogram's study suggests the Apple Watch alone does a better job of detecting abnormal heart rhythms than FDA-approved accessory KardiaBand. From Cardiogram co-founder Johnson Hsieh:
97% accuracy refers to the c-statistic, or area under the sensitivity-specificity curve. Surprisingly, both the sensitivity and specificity of DeepHeart were even higher than an FDA-cleared Apple Watch ECG attachment -- 98% (vs 93%) sensitivity and 90% (vs 84%) specificity.
Published in JAMA Cardiology this morning, the study confirms the results from a similar preliminary study done in May of 2017. According to Cardiogram, today's study marks the first peer-reviewed study in a medical journal that demonstrates popular wearables from companies like Apple, Garmin, Polar, LG, and others can detect a major health condition.

Atrial fibrillation, or an abnormal heart rhythm, is a condition that can be indicative of major health problems and it can lead to heart failure and stroke. Atrial fibrillation often goes undiagnosed, which is where the Apple Watch and other wearables can help. The Apple Watch won't replace a traditional EKG, but it can alert people to a problem much earlier than it might otherwise be detected. From the study's conclusion:
This proof-of-concept study found that smartwatch photoplethysmography coupled with a deep neural network can passively detect AF but with some loss of sensitivity and specificity against a criterion-standard ECG. Further studies will help identify the optimal role for smartwatch-guided rhythm assessment.
In addition to studies on the Apple Watch's ability to detect atrial fibrillation, Cardiogram and UCSF have also been working to determine if the Apple Watch heart rate monitor can also detect conditions like hypertension, sleep apnea, and early signs of diabetes. Preliminary studies have suggested all of these conditions could be spotted in data collected by Apple Watch and other common wearable devices.

Apple has been working with researchers at Stanford on its own study to determine whether the heart rate sensor in the Apple Watch can be used to detect abnormal heart rhythms and common heart conditions. While in the study, if an abnormal heart rhythm is detected, participants will be contacted by researchers and asked to wear an ePath monitor to test heart health.

Apple Watch owners can sign up to participate in the Apple Heart Study by downloading and installing the Apple Heart Study app. Those who want to join Cardiogram's studies can install the Cardiogram app and sign up to join the mRhythm study.

Article Link: Study Confirms Apple Watch Can Detect Abnormal Heart Rhythm With 97% Accuracy
 
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puckhead193

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I went out drinking with co-works one evening after work and my watch alerted me that my heart rate was over 120/125 or whatever it was. Was it because I was drinking or was it an error?
 
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Porco

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Mar 28, 2005
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#”Apple Rhythm, Apple Music, Apple Watch 4
Who could ask for anything more?”


There's your next ad campaign sorted Apple, you’re welcome.
 

oneMadRssn

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I went out drinking with co-works one evening after work and my watch alerted me that my heart rate was over 120/125 or whatever it was. Was it because I was drinking or was it an error?
Personally I don't find the Apple Watch heart rate sensor to be that accurate. When working out, it will regularly be off by a factor. To me, this means it's missing every other heartbeat. For example, my resting is ~70; when doing a cardio workout it will go up to 150 or so, then suddenly down to 75. Definitely not right, I am in the middle of cardio and feeling it, it's not 75.
 

Boatboy24

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Nov 4, 2011
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I went out drinking with co-works one evening after work and my watch alerted me that my heart rate was over 120/125 or whatever it was. Was it because I was drinking or was it an error?
Most likely the drinking, which can also cause huge spikes in your triglycerides. At last year's physical (after having 4 glasses of wine the night before), my triglycerides were triple what they were the year before (when I hadn't had any alcohol for a few days prior). Back to normal this year when not having a few the night before.
 

justperry

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Aug 10, 2007
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I'm a rolling stone.
Another paid research. It's the same off-the-shelf HRM as other watches.
Seems like you can't read, there are other brands mentioned/involved in the article, like LG and Polar amongst others.

(Macrumors) today's study marks the first peer-reviewed study in a medical journal that demonstrates popular wearables from companies like Apple, Garmin, Polar, LG, and others can detect a major health condition.


Why so negative, I think this is a good thing.
 
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now i see it

macrumors 601
Jan 2, 2002
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What's ironic is that extreme exercise like long distance cycling or marathon training can create atrial fibrillation (I would know). So while one function of the Apple Watch eggs you on to do more, another function is telling you to stop cuz you're messing up your heart.
 
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Cesar Battistini

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May 16, 2017
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Personally I don't find the Apple Watch heart rate sensor to be that accurate. When working out, it will regularly be off by a factor. To me, this means it's missing every other heartbeat. For example, my resting is ~70; when doing a cardio workout it will go up to 150 or so, then suddenly down to 75. Definitely not right, I am in the middle of cardio and feeling it, it's not 75.
Is the watch tight enough? That usually solves the problem.
 

topgunn

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Nov 5, 2004
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Personally I don't find the Apple Watch heart rate sensor to be that accurate. When working out, it will regularly be off by a factor. To me, this means it's missing every other heartbeat. For example, my resting is ~70; when doing a cardio workout it will go up to 150 or so, then suddenly down to 75. Definitely not right, I am in the middle of cardio and feeling it, it's not 75.
I workout with a Garmin chest strap heart monitor and an Apple Watch. The two are rarely more than a few beats off from each other.
 

asopublic

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Mar 27, 2008
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I went out drinking with co-works one evening after work and my watch alerted me that my heart rate was over 120/125 or whatever it was. Was it because I was drinking or was it an error?
It could have been any number of factors that raised your heart rate such as activity, hydration status, sexually attractive mates near you as well as arrythmia, panic or fear... As for alcohol effects on heart, here is an intriguing study https://www.ncbi.nlm.nih.gov/pubmed/28843731

If it interferes with your ability to function in your life in some way, or you have other symptoms with it, see your primary care provider.

I’m no longer a licensed physician. This is not medical advice, etc etc etc
 
This is great. I want more and more health related things like this going forward with Apple Watch.

I went out drinking with co-works one evening after work and my watch alerted me that my heart rate was over 120/125 or whatever it was. Was it because I was drinking or was it an error?
I get weird readings like this sometimes and I always wonder if it was accurate or not. I usually don't get extremely high (100+) readings while drinking, but sometimes have when sleeping AFTER a night of drinking. But I've observed that these extremely high readers virtually disappear when I use an arm band when sleeping (still high after drinking, but generally in the 80-100 bracket). So it may have something due to the wrist constricting in certain ways? Also the sensor has some scuffs from general wear and tear which could be contributing.

Personally I don't find the Apple Watch heart rate sensor to be that accurate. When working out, it will regularly be off by a factor. To me, this means it's missing every other heartbeat. For example, my resting is ~70; when doing a cardio workout it will go up to 150 or so, then suddenly down to 75. Definitely not right, I am in the middle of cardio and feeling it, it's not 75.
Try an arm band. This seems to help me a lot. But for me, the regular wrist location works pretty well for most cardio, but weight training and cycling does cause a problem. But I agree the apple watch to me seems kinda flakey which is why I'm so suprised anytime I see these studies praising it as one of the best HR monitors... Who knows. FWIW I've never tried another wrist HR monitor aside from AW.
 

AppleInLVX

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Jan 12, 2010
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I've been hit or miss with mine. For the most part (I'd say about 97% of the time *grin*) my values are what I'd expect. But then every now and again I'll get an anomalous reading like a spike to 145 for no reason, or a drop to 41 or 39 when there's nothing going on, and I'm clearly still standing). These are usually only one reading, and then back to normal again.

I find that it's worse when I have long sleeves on, so I'm wondering if the cuff or arm have something to do with the anomalous readings. But it's certainly not perfect. I tend to go by daily averages, which show a good measure in my experience. Doesn't help to detect abnormalities within small time frames, though.
 

oneMadRssn

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Sep 8, 2011
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Is the watch tight enough? That usually solves the problem.
It is tight, can't get any tighter with the sports band.

I suspect the issue is my hairy arms and sweat. Sometimes if I loosen the strap, and then move the watch down or up an inch to a dryer spot, it will pick up the right hr until that spot becomes sweaty under the watch.

Try an arm band. This seems to help me a lot. But for me, the regular wrist location works pretty well for most cardio, but weight training and cycling does cause a problem. But I agree the apple watch to me seems kinda flakey which is why I'm so suprised anytime I see these studies praising it as one of the best HR monitors... Who knows. FWIW I've never tried another wrist HR monitor aside from AW.
I've seen the TwelveSouth armband. Do you know of any others good ones? I think it's worth a shot.

I don't doubt that the AW is the most accurate wrist hr monitor, but that doesn't mean it is accurate on it's own. It could just mean the rest are even worse.

My specific situation is what worries me about these studies and imply the AW can be a medical tool. Having false positives is fine, for the most part. So the watch throws up a red flag saying someone has an unusual hr, but in reality everything is fine. No harm no foul. But false negatives can be deadly, if someone is relying on the watch to notice an unusual hr and it fails to do so. As I wrote, in my experience, the AW sometimes for whatever reason cuts my hr in half. To me, that would mean a lot more false negatives than false positives.
 
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asopublic

macrumors member
Mar 27, 2008
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This is a big deal medically. It’s really difficult to detect atrial fibrillation in many patients because it is intermittent. The longer you record heart rate/EKG the easier it is to detect-like months. Wearing an Apple Watch is cheap and easy to do. I spent zillions looking for afib over the years in stroke patients. If you detect afib in patients before stroke, you could offer anticoagulation to lower the risk of stroke ever happening. But you can’t test the general population for weeks on end with current methods.
 

370zulu

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Nov 4, 2014
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My AW3 is a requirement by my wife after my heart attack a while back. I wear it while I sleep and have it set to alert me if my HR goes above 120. When I was ill and had a fever, my HR went up and over 120 a few times and I had the watch wake me while I was trying to rest. This does make wife and I feel better about having some kind of warning that I may need to seek medical attention.

For that, the price of AW3 is definitely worth it for me despite the naysayers.
 

citysnaps

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Oct 10, 2011
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My AW3 is a requirement by my wife after my heart attack a while back. I wear it while I sleep and have it set to alert me if my HR goes above 120. When I was ill and had a fever, my HR went up and over 120 a few times and I had the watch wake me while I was trying to rest. This does make wife and I feel better about having some kind of warning that I may need to seek medical attention.

For that, the price of AW3 is definitely worth it for me despite the naysayers.
That's a great story. Thanks for sharing!
 

Craiger

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Jul 11, 2007
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I went out drinking with co-works one evening after work and my watch alerted me that my heart rate was over 120/125 or whatever it was. Was it because I was drinking or was it an error?
This happens to me when I take a hot bath sometimes.

These alerts are more like "hey if you don't know of a reason why your heart rate is so high right now, you may want to talk with a doc."
 
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Virtualball

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Jun 5, 2006
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It is tight, can't get any tighter with the sports band.

I suspect the issue is my hairy arms and sweat. Sometimes if I loosen the strap, and then move the watch down or up an inch to a dryer spot, it will pick up the right hr until that spot becomes sweaty under the watch.
I have an AW3 (with cellular for what it's worth) and have never experienced these problems. I work out 3x a week and also have hairy arms. In fact, I frequently compare the HR sensor in the new elliptical machines at my gym with the Apple Watch and they're usually only 1 beat apart.

Maybe you should look into getting a replacement?