Seven questions (and their answers) about the Apple Watch electrocardiogram, available today in Spain

In September 2018, Apple surprised everyone with the idea of ​​putting an EKG on their wrist. As of today, that functionality of the Apple Watch Series 4 is already available in Spain and our colleagues from Applesfera have already tested it. In that same report you can see how to activate it and more details on how it works.

However, there are many medical and health questions about the use of the Apple Watch that are on the table. I have collected some and I will update the article as we get more. This is what we know about the science and medicine of Apple Watch.

What is an EKG?

An electrocardiogram is a test (simple and painless) that records the electrical activity of the heart as it pumps blood through the body. This electrical activity is recorded with electrodes placed on the patient's skin and are graphically represented with very characteristic curves.

Standard practice requires 10 electrodes to be placed to find 12 leads (that is, to extract 12 different graphs from different areas of the body). Thanks to this basic electrocardiogram we can measure from the rhythm or regularity of the beats to the size, position and functionality of the atria and ventricles.

Cardiologists have developed a surprising ability to extract information from what, for the rest of mortals, are simple curves on paper. What together with its simplicity, availability and speed make it a fundamental tool of modern medicine.

Were there no portable EKGs?

Actually yes. The problem with the electrocardiogram has always been that there are many electrodes tied to a fairly large monitoring system: that prevented patients from using it autonomously, such as thermometers or sphygmomanometers. Since the 1940s, doctors realized that some ambulatory electrocardiography system was needed for certain pathologies that, due to their variability, were very difficult to detect in the office. In 1962, the first portable systems called holters began to be marketed in honor of the researcher who started building them in 1949 (and who refused to patent the system).

Holters are very small today and are often used when the electrical activity of the cardiovascular system needs to be monitored for long periods (24 hours or more). The biggest problem is that, by requiring the use of electrodes on the chest, they can be uncomfortable to use during sleep.

So does the Apple Watch Series 4 have a miniature holter?

No. It is something substantially different. Starting today, the Apple Watch Series 4 lets you monitor electrical activity in your heart system for thirty seconds by measuring constants on your wrist. In addition, the rest of watches from Series 1 will be able to analyze the changes in heart rate and notify the user as soon as there is a problem.

In other words, what the device does is monitor heart rate in real time and take snapshots at specific times (suggestive of problems) that help study cases in greater depth.

What is it for?

Despite the spectacular nature of the functionality, its usefulness is limited. It can be very helpful for certain people with a family history of heart disease or risk factors. But, above all, to people with atrial fibrillation. The latter is where Apple's attention has focused.

In short, Atrial Fibrillation occurs when the movement of the atria (the upper chambers of the heart) becomes uncoordinated and produces an irregular heart rhythm. As we said in September, it is not only the most common heart disease (it is estimated to cause 3.6% of general emergencies and more than 10% of hospital medical income); is that, in fact, it becomes more common with age (going from 1% in youth to 10% in the elderly).

AF usually has thromboembolic complications (an increased risk of stroke and mortality), so an early diagnosis that allows it to be under control is of interest. The problem is that there are types of AF that are difficult to diagnose. It is estimated that up to 65% of AFs can be of the 'paroxysmal' type; that is, his seizures last less than 2 minutes and, for this reason, it is almost impossible to study with an ECG.

Although the latest reviews indicate that paroxysmal AFs are not clearly associated with the risk of thromboembolism and death, they do cause great discomfort, anxiety and concern. Especially when patients notice fibrillation and know that "something is wrong." It is here when the 30 seconds of Apple Watch can be useful (because they allow you to take a snapshot of the crisis).

What is the problem?

Ivor J Benjamin, President of the American Heart Association, at the Apple event

The fundamental problem with this type of device is that the evidence suggests that using the electrocardiogram when it is not necessary generates more problems than benefits. That is, doing ECG to asymptomatic adults with low risk of heart disease because it is something of much-discussed utility.

In 2012, the U.S. The Preventive Services Task Force had already recommended not to do this type of screening (which is what they are called in medical jargon). And, after reviewing his recommendations, in 2018 he did it again.

The reason is that, even assuming some hidden cases are discovered, most of the population will be of no use and, in quite a few cases, false positives will subject patients to the negative impact of anxiety. and unnecessary treatments.

Is not the same with other devices such as thermometers?

Exactly the same as with other medical instruments. Health recommendations also do not recommend taking temperature or blood pressure for asymptomatic adults at low risk of disease. Thermometers are used when there is evidence of fever; sphygmomanometers, when there are problems with the tension (or risk factors) and we need to monitor its evolution.

Nothing prevents someone from having an electro at home. When necessary. So, and I think that this is not being stressed enough, it is not medically advisable to use the new functionality on our own.

How do we use it then?

With the help (and advice) of our doctor. First of all, from what we said: if we are not part of any risk group, using the functionality can give us more problems than benefits. False positives are an immense source of hours of waiting rooms, medical tests and unnecessary treatments that we would avoid just by following the recommendations.

Second, on the contrary, the false security that false negatives can give; that is, that the device tells us that nothing is wrong, but is wrong. With the data we have in hand, we still do not know how many FAs the device does not detect. And in those cases, without the keys that our doctor can give us, the Series 4 can end up delaying (and not advancing) the diagnosis of the problem.

And lastly, because, although Apple has designed a pdf that we can take to the consultation, today most doctors will not know what to do with it. As I was saying when it was introduced in September 2018, "the new Apple Watch Series 4 is a perfect metaphor for all the problems and opportunities of digital medicine that is about to come." A digital medicine that will require great changes, but that we should not expect to occur suddenly.

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