Wearable devices and Afib: How tech is helping to spot the heart condition you didn't know you had

Atrial fibrillation can be a killer - but a new generation of wearables could help spot the condition in people who don't even know they've got it.

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Atrial fibrillation is a heart a condition that may have no symptoms, causes your heart to beat out of whack, and can put your health at risk. It's also a condition that some of tech's biggest names believe could be tackled with some wearable technology and a dash of sophisticated data analytics and machine learning.

Atrial fibrillation means the upper and lower chambers of the heart stop beating synchronously, as normal hearts do. The condition can lead to blood pooling in the heart's upper chambers, running the risk of a clot forming -- a clot that could ultimately end up in the brain, causing a stroke. The symptoms of atrial fibrillation can include fatigue, dizziness, palpitations -- but the condition can equally come with no symptoms at all, meaning those with the condition can be completely unaware of the risks they face.

Apple started targeting the condition late last year, with the roll out of an 'ECG app' for the Watch in late 2018. The aim of the app is to spot the irregular heart rhythm that indicates atrial fibrillation in people without symptoms, allowing them to get to the doctor before any problems develop. The watch and ECG app can be used for background monitoring, or for spot checks when the wearer places a finger on the its crown. 

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Apple is not the only technology company to spot an opportunity to use wearable technology to fight atrial fibrillation. iRhythm, spun out of Stanford University's biodesign centre six years ago, makes a wearable patch that can detect atrial fibrillation, and has recently partnered with Verily, the health sciences arm of Google parent company Alphabet, to work on the condition. 

"Cardiac arrhythmias, both symptomatic and asymptomatic, are extremely important, generally poorly diagnosed with technologies that are as old as 50 or 60 years, so there has been very little innovation within that space," Kevin King, iRhythm's CEO, tells ZDNet.

While Apple's app targeted consumers, iRhythm describes its kits as "medical-grade". People with suspected atrial fibrillation would wear a Zio patch, with readings decoded by the company's AI-based data analytics, and the results presented to the patient's doctor.

Ultimately, hardware like iRhythm's could end up replacing the Holter monitors that hospitals and cardiology clinics typically use for monitoring or diagnosing arrhythmias.

Atrial fibrillation can be tricky to catch, particularly if it's what's known as 'paroxysmal' -- med-speak for 'it comes and goes'. However, Holter monitoring allows medics to observe the wearer's heart rhythm over a longer time than the 10-second window of a normal ECG, meaning there's a greater chance of finding atrial fibrillation in someone that has the condition. 

Holter monitors are usually boxes around the size of a small phone with a handful of electrodes, all attached to the chest. The new generation of more comfortable wearable ECG monitors including iRhythm's are smaller, stick-on patches applied directly to the chest, and don't need any additional electrodes on the skin.

While a typical ECG done in a hospital records the heart for a matter of seconds, Holter monitors and Zio patches can record for hours or days. According to King, a Zio patch can create the equivalent of 30,000 to 40,000 pages of heart-tracing data. 

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"That amount of information is just too much for mere mortals, physicians or their staff, to understand. Part of our service is an analytical layer that synthesises that information into an actionable report of about 10 pages… we're providing meaningful insights to [the physician] about the condition of their patients so that they can treat them more rapidly," he says. Spotting atrial fibrillation early has its benefits: common heart meds can be used to cut the stroke risk that AF causes, so treating the condition early can reduce the chance of the death or disability that can follow a stroke. 

While there's no word yet on the potential fruits of iRhythm and Verily's joint work, King says it will involve "wearables, data analytics and data management".

iRhythm and Verily are trying to determine just how long patients will put up with wearing a heart-rhythm-tracking device. The longer a patient wears the patch, the more likely the system is to find AF if they have the condition, but equally the greater the cost and the lower the likelihood the patient will be happy to keep having a sensor strapped to their chest. Verily and iRhythm are looking to find the length of time that strikes the right balance between accurate diagnosis, cost, and convenience for the patient.

The right style of hardware will be key to creating a device that patients are happy to wear in the long run. Verily has been investigating wearables as part of Project Baseline, a research effort to map human health. "When we started working with Verily, we asked this question of how long the patient could tolerate wearing that device, and that's one of the fundamental questions that we're trying to address with Verily -- what would be the best form factor?" King says.

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As well as answering hardware questions, the pair will be setting machine learning onto digesting those thousands of pages of data created by a heart tracing, alongside all the other reams of data a patient may carry with them -- patient notes, scans, and so on. By combining all that data together and using machine learning to query it in depth, it's hoped that new insights into atrial fibrillation will emerge.

"What we're planning to do [with Verily] is use the best of our individual technologies, or combine our individual technologies. Verily is bringing to us the proven machine-learning capabilities, the ability to curate data, data management capabilities, as well as the expertise they have in wearable technologies, so that we can begin to identify these patients that are at risk of atrial fibrillation," King added.

High blood pressure and age are among the known risk factors for developing atrial fibrillation. Given the prevalence of the condition, and the ability for the latest generation of consumer and medical wearables to detect the condition, we may one day see such devices handed out to screen for AF, much in the same way national screening programmes look for conditions such as breast cancer, bowel cancer, or aortic aneurysms. By screening everyone at risk, medics can help identify people with atrial fibrillation who don't know they have it, and act before it becomes a problem.

Due to the relative newness of using wearables to detect or rule out atrial fibrillation, there are still questions to be answered on how such screening would work - who should be tested, how often, and for how long? "I think we're going to try to find that answer in our research and development efforts here between the two companies. We want to find the optimal technology, and we want to find the optimal type of patient," King says.