Should You Really Use Your Smartwatch Or Fitness Wearable To Monitor Your Heart?

Wearable devices that can record heart rate can be useful for tracking your fitness, but can you really use them to track heart rhythm disturbances?

The short answer is maybe, and it depends on who you are. These devices are great, but there are a few things to be aware of.

A number of large studies have been conducted to see how wearables can look for signs of a common heart rhythm problem called atrial fibrillation, which can lead to stroke.

In a new Frontiers review published in Circulation , we and our colleagues at the AF-Screen International Collaboration evaluated current data, including three very large studies: Fitbit Heart Study (funded by Fitbit); The Apple Heart Study (supported by Apple) and the Huawei Heart Study (Huawei participated in the development and optimization of the application but did not fund the study).

What is atrial fibrillation?

Atrial fibrillation is the most common heart rhythm problem (arrhythmia). Up to 80% of patients may have no symptoms.

Atrial fibrillation becomes more common with age and can significantly increase the risk of stroke. Due to age and / or other risk factors, such as hypertension and diabetes, patients at high risk for stroke-related atrial fibrillation are usually prescribed anticoagulants.

Consumers are becoming more and more heart rate monitors. This includes wrist electrocardiography (ECG) and wrist-based technology for smartwatches, other wearable devices, and consumer devices. They are often marketed as health and wellness products.

Australian guidelines and other international guidelines recommend periodic screening for atrial fibrillation in people aged 65 and over.

However, new technologies (including wearable devices) allow consumers to record their heart rate whenever they want and to continuously monitor their heart rate. This technology can empower consumers and deliver important information, but it has limitations.

How accurate are wearables and other consumer devices?

Short answer. Wearables are likely to be fairly accurate (often above 95%) in identifying atrial fibrillation. However, the information is often based on studies involving a limited number of people.

Some devices include an algorithm that automatically determines whether the heart rhythm is regular ("normal sinus rhythm") or irregular (which may indicate atrial fibrillation). These algorithms usually require regulatory approval (e.g. Therapeutic Goods Administration (TGA) in Australia).

However, device manufacturers often don't release many details about the accuracy and performance of their devices. The TGA does not regulate wearable devices that merely monitor heart rate or activity without serious health claims.

It is important that medical device manufacturers.

• accurate in their health claims

• do not advertise unproven benefits

• report the accuracy and performance of their devices in different populations.

Although the Fitbit, Apple and Huawei studies were very large, the calculations used to determine the accuracy of the device could be based on small numbers because not many study participants had atrial fibrillation.

For example, the Apple Heart study involved 419,000 participants; that's a lot of people. However, accuracy was calculated by comparing simultaneous atrial fibrillation recordings on a smartwatch heart rate irregularity detector and an ECG in just 86 people.

Who are they good for?

If you have symptoms or are over 65, wearables can be very helpful in detecting atrial fibrillation.

Wearable devices are great as "event recorders" for someone who has a symptom (such as heart palpitation) that could be an arrhythmia. Devices with ECG capabilities, such as Apple Watch Series 4 or later, Withings Scanwatch, and KardiaMobile, are particularly useful because they provide more information. If you get an ECG recording during symptoms, you can give it to your doctor, who can help guide you further tests.

Wearable devices are also useful in helping people diagnose atrial fibrillation early. Ideally, this should be accompanied by comprehensive care, including risk factor reduction and lifestyle modification to reduce progression and complications (especially in young adults who may not need any specific therapy).

We also know that wearables can be used to track large numbers of people: 457,000 in the Fitbit study, 419,000 in the Apple Heart study, and 188,000 in the Huawei study. However, the number of new atrial fibrillations found in these studies was low (less than 1%), mainly because the study participants were very young (the median age in all three studies was 41 years or less).

So what are the problems?

More data isn't always better. If your GP checks your heartbeat on an appointment, finds it irregular, and an EKG confirms it is atrial fibrillation, chances are you have at most (or all) atrial fibrillation:

The risk of atrial fibrillation is the same for people with and without symptoms, and we know how to treat the condition.

However, wearable devices can track people's heart rate much more often and for longer. The more you search, the more you find atrial fibrillation, but we're still not sure what to do.

So while wearables increase atrial fibrillation detection, we don't know if they will prevent strokes.

Many people who buy clothing accessories are younger and less vulnerable. We are still not sure what it means when a young person with few or no risk factors has brief episodes of atrial fibrillation.

More evidence is needed, ideally from high quality independent randomized trials.

Cons and data

Even highly accurate devices can sometimes give false positives, more often in young people who are at lower risk for atrial fibrillation. Additional tests may be needed, which increase costs and can lead to unnecessary testing, which can cause problems and possibly discomfort.

Data privacy is also a concern. In many countries, there are significant gaps in data protection legislation and usage regulation.

Consumers often lack ownership or control over health plan data.

What should i do if my handheld device tells me i have atrial fibrillation?

If your device indicates that you may have atrial fibrillation, keep a copy of the measurement and discuss the result with your doctor. Further testing or treatment may be needed. Don't panic though.

It should be remembered that one size does not fit all. Either way, wearables are here to stay. We need to make sure we understand their advantages and limitations.

This article was reprinted from The Conversation under a Creative Commons license. Read the original article.

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