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Apple Watch for Heart Health: A Cardiologist’s Word of Caution

One of these phrases may be true (but not as it was intended).

And the other should not be used at all – at least not yet.

Apple Watch, Series 4

The watch’s new heart health features include the ability to record a simple electrocardiogram (ECG) and a rhythm monitoring app capable of detecting a heart rhythm problem called, “atrial fibrillation” (Afib).

Although Afib is a heart rhythm problem, the main reason it is dangerous is because it increases the risk of stroke. Because the top chambers of the heart are not beating in a coordinated fashion in Afib, blood clots can form in the crevices of the heart. If these blood clots break off and travel to the brain, they cause a stroke. Since Afib doesn’t usually cause symptoms and it can be intermittent (come and go), there are many people who have Afib, but aren’t aware of it. The idea behind the Afib detection feature of the Apple Watch is by notifying someone they have Afib, that person could work with their doctor to assess their risk of stroke and take any necessary precautions.

So, if the Apple Watch can detect a problem that people would otherwise not be aware of and potentially get them to lifesaving therapy, why are many cardiologists concerned that the Apple Watch may create more problems than it solves?


The phrase “game-changing” has become so commonly used that it has lost some of its meaning. But when the world’s most valuable company and the president of the American Heart Association announce a new feature as “game-changing”, the world takes notice. Many cardiologists, however, are concerned that the “change” may be that people who don’t have a heart problem now have technology mistakenly suggesting that they do, leading to a lot of expensive testing to prove they are healthy.

Cardiologists are uneasy because we know when a test that isn’t perfect (which is all of them) is applied to a group of people where the disease is rare, it’s more likely that a positive test is in fact a false positive and not a true positive.

Since Afib is most common in an older population and the Apple Watch users are (presumably) younger, it’s possible that cardiologists and emergency rooms will be overwhelmed with people whose Apple Watch indicated they have Afib when, in fact, they don’t. For these people, it is likely this will lead to expensive testing to reassure them that their heart is, in fact, fine.

But, wouldn’t that be a small price to pay for the “lifesaving” benefits of the Apple Watch?


Unlike game-changing, “lifesaving” is a word that is used carefully, at least in medicine. Doctors are trained to be cynical about claims, particularly from commercial interests, that haven’t been demonstrated in a quality clinical trial.

This is how it should be. Physicians have an obligation to protect their patients from unproven interventions. “First, do no harm” is a fundamental principle of quality medical care and that shouldn’t change, even for Apple.

Where is the proof that the Apple Watch saves lives? Well, there is none. No data about the effectiveness of the Apple Watch has been published so far in a peer reviewed journal, let alone the watches’ effect on mortality.

No one doubts that the Apple Watch (when it is available) will detect Afib in people who are unaware that they have it, and those people will be put on stroke-preventing blood thinners (or will take other precautions). We know this works because, in fact, there are several devices that do this now including holter monitors, event recorders, implantable loop recorders and the AliveCor device.

But what if there are unintended consequences of the Apple Watch? What if there are people who stay home during a heart attack because their Apple Watch didn’t say they were having a problem? Or if the testing done for the people with false positive readings causes harm? Or people are put on blood thinners who don’t need them and have bleeding complications? These are the questions we don’t have answers to yet – and this is why we can’t use the word “lifesaving” when talking about the Apple Watch.

The Future of Digital Health

Personally, I’m excited about the possibilities of remote monitoring and technology in healthcare (I particularly like the fall detection feature of the new Apple Watch). And I applaud the companies, large and small, that are seeking innovative ways to improve the care I deliver to my patients.

But we can’t lose sight of one of the fundamental principles of medicine: “First, do no harm.”



BY R. TODD HURST, MD, FACC Board-certified cardiologist posted on OCTOBER 23, 2018, "Apple Watch for Heart Health: A Cardiologist's Word of Caution", www.webmd.com, https://blogs.webmd.com/heart-health/20181023/apple-watch-for-heart-health-a-cardiologists-word-of-caution.

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