Lancashire Objective Volume Evaluation of Leg Oedema in Heart Failure Second Pilot (LOVE-HF-2)

Heart Failure is the final common pathway of most forms of cardiovascular disease. In the United Kingdom (UK), it affects around 900 000 people, causes or complicates around 5% of adult emergency hospital admissions and consumes up to 2% of total National Health Service (NHS) expenditure. An important part of discharge planning includes measures such as early follow up in order to prevent readmissions. The hallmark of heart failure is fluid retention and between 2009 and 2016, 43% to 50% of hospital admissions were associated with peripheral oedema. Therefore, early recognition of this and treatment of the congestion may prevent hospital admissions. In clinical trials, management strategies have included patient education, telemedicine and remote monitoring. The main non-invasive method for detecting fluid retention has been the use of weight as a surrogate marker.

The Heartfelt device is an invention that uses a system of cameras in a compact device in order to generate 3 dimensional images of the feet and lower legs. The volumes can then be calculated and thus, changes in amount of peripheral oedema can be estimated. In a clinical trial (NCT02993601) performed by the Heart Failure team at the Royal Brompton Hospital, there was good correlation between measurements made by Heartfelt and a water displacement method. The resolution was as good as 20mls.

By positioning the Heartfelt device in the bedroom, automatic measurements can be made whenever the subject gets in and out of bed. Images are only taken of the specified subject. Data is censored so that the part of the body which is 50cm above the floor is not stored. Encrypted, anonymised data is transmitted over the internet to the company's secure servers. Personal identifiable data (participant name, address, age…) is stored on an encrypted hard drive, along with linkage information (device serial numbers) to associate the participant identifiable data with the data captured in the home. Therefore, data collection is not only secure but entirely passive, which is a major advantage compared with previous non-invasive methods and it is applicable to a very wide range of compliant and non-compliant patients.

The LOVE-HF trial (NCT04787380) demonstrated that the number of days with missing data collected by the Heartfelt device was significantly lower than that of the weighing scales, providing a promising tool for home patient monitoring.

Being able to demonstrate that the device can provide a measure of oedema that is clinically relevant over the full range of individual patient's oedema is the main objective of this study as this will further adds to the validation of the device.