At-home ‘foot-recognition’ AI scanner can prevent heart failure hospitalizations

A home device that scans someone’s feet as soon as they get out of bed in the morning could keep people with heart failure out of hospital, according to research presented Tuesday at the British Cardiovascular Society conference in Manchester.

More than a million people in the U.K. have heart failure which, when not fully controlled by medication or lifestyle factors, can lead them to be hospitalized.

Now an AI device with “foot recognition,” similar to face-recognition technology, could potentially flag when heart failure is becoming severe and life-threatening—delivering an alert 13 days before a person would end up in hospital, according to new research supported by the National Institute for Health and Care Research (NIHR).

The wall-mounted device, which is roughly the size of a smart speaker, detects a build-up of fluid in the feet and ankles called edema, which is one of the “big three” signs heart failure is becoming severe, along with sustained weight gain and breathlessness. This edema occurs when the heart is not pumping blood around the body as well as it should.

The device, produced by a small Cambridge-based start-up company called Heartfelt Technologies, which takes 1,800 pictures a minute, images the foot and lower leg at multiple angles using AI detection of their precise position, then calculates the volume of fluid they contain.

Researchers say the scanner can trigger an alert to a heart failure team when someone has edema that is getting worse, so they can be advised to take rapid action like increasing their medication, which could keep them out of hospital.

Dr. Philip Keeling, senior author of the study and a consultant cardiologist at Torbay and South Devon NHS Foundation Trust, said, “This device detects one of the big three warning signs for people with heart failure before they end up in hospital.

“Only about half of people admitted to hospital with heart failure currently get assigned an early review by a heart failure nurse who can check to see if they are suffering a harmful build-up of fluid because their heart is not working properly.

“Amid a shortage of heart failure nurses, a device like this can be like a virtual nurse, tracking people’s health.

“Living with heart failure can be overwhelming, with all the medications, medical tests and appointments, and the requirement to monitor your own health.

“This scanner, once it is installed, just automatically keeps an eye on you and alerts the health failure nurse, which is a huge relief.”

The FOOT study examining the scanner involved 26 patients across five NHS trusts, who had also been asked to weigh themselves regularly to track the progression of their heart failure.

Among those who had the scanner in their home for at least two weeks before it triggered an alert, three people were hospitalized with heart failure. The alerts came between eight and 19 days before their hospitalization—giving the scanner an average prediction time of 13 days, which researchers say is adequate time to take action to keep someone out of hospital.

The device is typically installed beside someone’s bed, where it scans their bare feet and lower leg. This is done automatically, and continuously, without requiring any involvement from the person being scanned. The foot scanner simply needs to be plugged into the mains, and records real-time images automatically.

It can work without Wi-Fi, for older people without internet access. To ensure privacy, the device only scans the legs to a height of 50cm from the floor, taking in much of the lower leg, from the toes to just below the knee.

The FOOT study also suggests the scanner better predicts the risk of hospitalization in heart failure patients than the more conventional method of asking them to monitor their weight daily (to check for weight gain caused by the fluid build-up in their body).

In the study the scanner accurately predicted five out of the six hospitalizations which occurred among all participants. The weight checks, which triggered an alert if someone gained 2kg or more over three days, predicted none of these hospitalizations because that threshold was not met.

At the end of the six-month study, 82% of remaining study volunteers living at home—18 out of 22—chose to keep the device.

Edema is a warning sign for acute heart failure as it is fluid retention caused by the heart failing to properly pump blood to the kidneys, so that it is harder for them to remove water and salt from the body.

Hospitalizations of people with acute heart failure are important to avoid because they threaten the health of patients, and because of their impact on hospitals, as people are typically kept in for around 10 days.

The researchers now plan to test the Heartfelt device, which can even scan feet through thin socks, on a larger cohort of patients. The foot-recognition technology is important if the device is to be rolled out to larger groups of people, such as in care homes.

So far it can accurately detect one person’s feet and lower legs out of a group of 100 people’s feet, but it may have identification issues if more people walk past, as would happen in larger residential homes.

Professor Bryan Williams, Chief Scientific and Medical Officer at the BHF, which was not involved in the research, said, “This small study suggests a simple device could significantly improve outcomes for at-risk patients with heart failure by keeping them out of hospital.

“This study is a good example of how technology might aid earlier interventions and treatment, by allowing people to track a key sign of their heart health at home.

“Innovations with the potential to transform heart care in this way are a major part of the BHF’s goal to save and improve lives of people living with cardiovascular disease.”

Provided by
British Heart Foundation