The New Apple Watch 4: Cardiac Accuracy Unknown, "Game-Changing" Benefits Overblown

On February 10, 2014 AliveCor, Inc. announced that its heavily validated personal  mobile ECG monitor had received FDA over-the counter clearance. Previously the device, which allows recording of a single-lead ECG and, in conjunction with a free smart-phone app, can diagnose atrial fibrillation was only available by prescription.
Since 2013, I have been successfully using this device with my patients who have atrial fibrillation (and writing about it extensively)

Apple COO Jeff Williams standing in front of (presumably) an ECG obtained by Apple Watch 4. It’s OK quality (but smallish p waves). Is that the best they could do? Notice that it is making a diagnosis of sinus rhythm. This PDF can be mailed “to your doctor.”

I was shocked, therefore, to hear the COO of Apple, Jeff Williams, announce that Apple will be offering in its new Apple Watch 4  “the first ECG product offered over the counter directly to consumers.”
This seemed blatantly inaccurate as AliveCor’s device clearly preceded by 4 years Apple’s claim.
Furthermore, AliveCor’s Kardia Band which converts any Apple Watch into a single-lead ECG  (which I’ve written about here and here) has been available and providing the Apple Watch-based ECGs since November 30, 2017.
AliveCor has an outstanding website which documents in detail all the research studies done on their products (there are dozens and dozens of linked papers) and all of their press releases dating back to 2012. It also explains in detail how the product works.
The title of their November 30, 2017 release was  FDA Clears First Medical Device Accessory for Apple Watch®
AliveCor shortly thereafter (December 12, 2017) announced Smart Rhythm , an Apple Watch app that monitors your rhythm and alerts you if it thinks you are in atrial fibrillation. I’ve discussed Smart Rhythm here.
Apple’s Watch will tell you that you are not in atrial fibrillation. Given that we don’t know how accurate it is, should that be reassuring?

The new Apple Watch’s rhythm monitoring app sounds a lot like Smart Rhythm but without any of the documentation AliveCor has provided.
So, within 10 months of Alivecor providing the world with the first ever wearable ECG (and proven its accuracy in afib) Apple seems to have come out with a remarkably similar product.
The major difference between Apple and AliveCor is the total lack of any reviewable data on the accuracy of the Apple device. Yes, that’s right Apple has provided no studies and no data and we have no idea how accurate its ECG device is (or its monitoring algorithm).
For all we know, it could diagnose sinus rhythm with frequent APCS or PVCs consistently as atrial fibrillation, sending thousands of Watch 4 wearers into a panic and overloading the health care system with meaningless alerts.
Apple’s website claims

Apple Watch Series 4 is capable of generating an ECG similar to a single-lead electrocardiogram. It’s a momentous achievement for a wearable device that can provide critical real-time data for doctors and peace of mind for you.

Apple’s “momentous achievement” was actually achieved 10 months earlier by AliveCor and if its monitoring algorithm and ECG system are significantly worse than the proven AliveCor system they will be destroying the peace of mind of users.

Electrodes built into the Digital Crown and the sapphire back crystal allow sensing of cardiac electrical signals. Did Apple get this idea from AliveCor?

After describing the Apple Watch’s new health features, Jeff Williams introduced Ivor Benjamin, MD, the President of the American Heart Association. Benjamin proceeded to describe the new Apple Watch cardiac features as “game-changing”, noting that the AHA is committed to helping patients be “proactive.”
Does  Benjamin have access to the accuracy of the Apple Watch ECG sensor? If so, he and the AHA should immediately share it with the scientific community. If not, by endorsing this feature of the Watch he should be ashamed. Users need to know if he or the AHA was paid any money for this appearance. Also, we should demand to know if (as the prominent AHA logo suggested and news reports implied) the AHA is somehow endorsing the Apple Watch.
Frequent readers know I’m a huge Apple fan but this Apple Watch business makes me think something is rotten in the state of Apple.
Skeptically Yours,


15 thoughts on “The New Apple Watch 4: Cardiac Accuracy Unknown, "Game-Changing" Benefits Overblown”

  1. I was recommended the AliveCor by Dr. Pearson when it first came out.I purchased one immediately. When I think I believe I am in Afib, I take a reading and send it to Dr. Pearson. It is so great to have a way to communicate my readings to Dr. Pearson. He can advise me if it is concerning. I am not am Apple product user and am sorry to hear they are taking credit for something they did not do. I believe my AliveCor is easy to use and convenient

  2. I have been using the Alivecor Kardia band since it 1st came out. I LIKE the PRINICIPAL of it quite well — &, WHEN, it is WORKING — & ‘young’ — it seems to a good job. However, I’m on my 4th band (@$200 per pop) in just over 1yr — &, as the band ‘ages’ — the consistency / reliability of the ekgs gets (QUITE) FLAKY. Alivecor tech support also is VERY FLAKY (imo) — & even when the band ‘goes bad’ (say in 3-months) they do NOTHING to replace it (other than give you a RUN-AROUND). Additionally, the band (& related apps on the Apple watch) DRAIN the battery life (BIG TIME) — so that I get only 1/2-2/3rd of a day — before you have to RECHARGE the phone. NET, NET, I’ve pretty much ‘given up’ on this ‘temperamental’, ‘battery-DRAINING’ & expensive TOY — which does a GOOD / RELIABLE job (only) about 1/3-1/2 of the time — & 1/2 of the day… Check out ALL of the reviews on Amazon(probably 1/3-1/2 of them) — which essentially say the SAME thing that I am ‘passing along’ here… Personally, I think that your UNABASHED PRAISE for the product IGNORS the ‘other elements’ of the product / support / service…
    Not withstanding your ‘over-enthusiasm’ (imo, in THIS case) — I REGULARLY ENJOY your (consistently) interesting column & comments… Keep up the GOOD WORK…

    • James,
      Just to be clear. My praise is for the 99$ Alivecor Mobile ECG device, not the Kardia Band. In my last post on this I mentioned that none of my patients have the Kardia Band. I’ve gotten a fair amount of email about the Kardia Band which is probably worthy of a separate post as time permits. Perhaps, if AliveCor people are reading this they can comment on you Kardia Band concerns.
      With regards to Amazon reviews, they are often unreliable.

  3. Apart from the hyperbolic Fruity Marketing, has anyone wondered ‘where’ your EKG data is going to end up? – that you don’t know about.
    Some of those wrist monitors require a downloaded App for your phone, which “needs” access to your contact list, camera(s), GPS etc and warn that it’s activities may “cost you (call/data charges) money”.

  4. The fine-print “ECG app coming later this year.” just sounds like “selling futures”. So the watch will be able to take an ECG, are they offering the “submit single ECG for evaluation”, and “subscribe for regular ECG evaluations” service?
    They have been running their own abnormal HR detection study publicly with Apple watch owners. Are they going to start a public ECG collection with abnormality detection study at this point?
    The way they are hyping it, without any details is just frustrating.

  5. I’ve been following this area with interest too, Doc, as passive data collection interests me. Cardiogram has been studying this separately (, and Apple studied it in cooperation with Stanford University (, but I’d really like to see more data and time also. It seems that money can pay for speedy FDA certification yet again, while smaller companies with superior devices get left behind yet again. Sadly, the result is a big headline, with little substance behind it. Unfortunately, I find this to be a common occurrence, which leads me to be skeptical of most scientific research. Each study has to be carefully examined, biases confirmed and understood, results examined etc.
    I do see value in the Apple Watch as a smarter version of the “I’ve fallen and I can’t get up device”, and hopefully, within 2 or 3 years, the thing will be accurate and providing useful data.
    In the meantime, I’d just be happy if Apple would let me export my Apple Health data without that app choking and dying (granted I have more data than most). I’m confident we’ll have more fluff in future product, like great broken heart emoji’s, but I’m not confident this device will give me accurate information about whether I’m in NSR. Keep in mind that for my 14 months of constant A-Fib, my Apple Watch Series 3 device measured my heart rate at half the rate of my heart rate strap, because it was detecting the high speed flutter in the top chambers of the heart.
    In either case, the beat goes on…

  6. I have been using my Kardia band since it came out and getting details monthly reports. I, too have been sharing with my cardiologist. As a big fan of apple products I am concerned going forward. Will my watch with Kardia continue to be supported? I was hoping for a partnership that might make a better band. ( a more attractive one?). So disappointed to see Apple’s approach to just leapfrog because they CAN!

  7. Excellent analysis Doctor. I was duped by
    The Apple news release and was to chat with
    You in this regard at my next visit. I am an AliveCor owner, and was thinking of the mobility of a wrist watch. I now have my
    Knowledge, thanks to you.


Please leave your comments. The skeptical cardiologist loves feedback. He reads all and replies to all that warrant a reply.