Could your Apple Watch save your life? How smartwatch sensors could help tackle a dangerous heart condition

A collaboration between Cupertino and Stanford University's medical school is aiming to conduct what could be the biggest research study into atrial fibrillation.
Written by Jo Best, Contributor

Video: Apple takes on healthcare industry from patient to provider

You already know your smartwatch is a pretty smart bit of kit. It tells you how many steps you've taken, how many calories you've burned off, and your resting heart rate. But could it one day even save your life?

A new research project using data gathered from Apple Watches has the potential to do just that. The Apple Heart Study, a collaboration between Apple and Stanford Medicine, is designed to identify atrial fibrillation -- a condition that can lead to serious complications, such as heart failure and strokes.

Around one in four people will experience atrial fibrillation in their lifetime, and it's thought to account for 120,000 deaths a year -- but some people with the condition may not even be aware they have it.

The Apple Heart Study is open to US residents aged over 22 with a 2016 Apple Watch Series 1 or later. All participants have to do is download the Apple Heart Study app from the App Store and install it on their phone and Watch. The data gathered by participants' Watches will be used to study the incidence of atrial fibrillation in the population at large, and help improve the technology used to detect heart arrhythmias such as AF.

"Today we don't really know the true incidence of atrial fibrillation because it can be intermittent, and because none of us, or very few of us, have been constantly monitoring our heart rate... What we hope to gain in the study is an understanding of how atrial fibrillation can be detected, and how prevalent it is, and ultimately what should be done to treat it -- when it should be treated, and perhaps, when it should not be treated," Stanford Medicine's dean Dr Lloyd Minor told ZDNet.

Image: Apple

In a normal heart beat, an electrical signal is generated in the sinoatrial node, a small area in the wall of one of the heart's upper chambers, called atria. The two chambers contract, and the electrical signal is passed on to the lower chambers, known as ventricles, telling them to contract just a fraction of a second later. In this way, blood can be moved from the atria, to the ventricles, and on to the rest of the body.

In atrial fibrillation, the electrical signals that tell the chambers to contract is fired off abnormally, and the upper chambers contract more than they should and with an erratic rhythm. As a result, blood can stay in the atria too long, where it may produce a clot -- which can ultimately end up in the brain, causing a stroke.

According to CNBC, the Watch will use LEDs and light-sensitive conductors to monitor blood flow at different points in a patient's wrist during the study. While a healthy person without atrial fibrillation should have a pulse with a regular rate, rhythm, and character, someone with AF may have a pulse that's irregular, or not as strong as it should be.

Some people with atrial fibrillation may have relatively minor and non-specific symptoms, such as fatigue and weakness, or even no symptoms at all. If the Apple Heart Study app detects a potential arrhythmia in a participant, they will be notified through the app and offered a telehealth consultation with healthcare provider American Well. "In general, [the American Well primary care provider] would be an informed study monitor and an informed coach to a patient about the next step in the evaluation would be," Minor said.

As well as explaining to the participant what AF is and what it might mean for them, American Well may also offer the participant an ePatch -- a mini electrocardiogram (ECG) worn on the chest -- to use for seven days, to further investigate any potential AF. Up to this point, all the investigations are free, but should a participant ultimately receive a diagnosis of AF, they'll need to fund any treatment themselves.

The Apple Heart Study was announced in late November, and will be accepting participants until August 2018.

The future of arrhythmia medicine?

Apple and Stanford have been working together on the intersection of tech and heart health since the creation of an iOS app called MyHeart Counts, built on Apple's ResearchKit framework (an Android equivalent built by the medical school also exists). Among other features, the app measures users' performance in the three-minute walk test: the app records how far an individual can walk within the span of three minutes, which can be used as an indicator of a person's overall cardiovascular health.

While Apple doesn't disclose how many downloads or active users an app has, the data generated by MyHeart Counts has allowed the university to gain more insight into the three-minute walk test than any other research project. "Just from that study, we have more data on three-minute walk test than all the previous published series of the three-minute walk test," Minor said.

He expects a similar level of response to the Apple Heart Study app. "We'll be looking at the information being sent when possible arrhythmia is detected by the Watch, we'll be looking at the information coming from the ePatch, and we'll be looking at how that compares to other demographic features of the participants, in so doing, we fully anticipate this will be at the conclusion of the study, probably the largest study of heart arrhythmias to have been conducted on a large-scale basis."

Minor added: "The opportunity today to get engagement with such a huge number of people is what is so appealing to us, and the fact that data science is now a highly-evolved field, so we can get information from these large datasets that directly relate to health and healthcare."

The study could well be a turning point in the investigation of atrial fibrillation. However, there is a risk that the study could be skewed by the profile of the individuals who might buy or own an iPhone and Apple Watch. Apple Watch owners are ostensibly younger, wealthier, more interested in taking care of their health than the average individual, and largely male. Could these demographics mean the study won't be representative of the US population as a whole? "This is a starting point, and the study is designed using the sensors in the Apple Watch, and its pairing to an iPhone. There very well may be comparable follow-on studies with a similar intent with different devices," Minor said.

And, given the wide spectrum of presentations of atrial fibrillation -- mild to severe, intermittent to constant -- the Watch's ability to monitor AF could mean that in future it could be used to monitor and finetune treatments for the condition.

Minor likened the potential usefulness of consumer-facing tech such as the Apple Watch to that of sensors on aircraft that are responsible for carrying thousands of passengers every day.

"Today when we're on an any commercial airliner, those planes have sensors in them that are continually monitoring the health of the engines -- the sensors are sending information back down to ground-based monitoring, and when the engines need servicing, there are indicators that appear; if there's going to be a serious problem with the engine, then there are other indicators appear. The way the engine is functioning is continuously being monitored and I think that's one of the reasons we've seen a dramatic improvement in the safety of airplanes over the past several decades. But we don't have anything comparable to that in human health, and yet I think that's within our grasp."

The explosion of consumer technologies like fitness trackers, smartwatches, and other wearables, coupled with the rise of data science and AI in medicine, means "this is a really exciting time in medicine", according to Minor.

"Technology is enabling each of us to take charge of our health and in so doing, gathering lots of useful information to better determine care delivery pathways and how we can be effective in our health... there are a whole host of things that digital technologies are bringing these very positive changes in the way we think about and deliver healthcare and the way each of us is able to engage in our health."

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