Lancashire Objective Volume Evaluation of Leg Oedema in Heart Failure

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.

Our hypothesis is that the Heartfelt device can directly detect the increase in peripheral oedema associated with heart failure decompensation and that, on average, the number of days with missing data collected by the Heartfelt device will be lower than that of the weighing scales.

Blackpool Victoria Hospital provides acute heart failure service both for in-patients and out-patients, including capacity to administer parenteral furosemide in hospital cardiac day case unit, community or home settings.

Participants with chronic heart failure will be monitored in their home using the Heartfelt device (experimental arm only). Participants in both arms will also receive standard care. "Standard care" means that participants will be encouraged to report symptoms and weigh themselves on a regular basis (as per the recommendation of their doctor or heart failure nurse) reporting them without delay. This will be done in line with current advice given to heart failure patients locally, which is that patients should record their weight in a diary and seek urgent medical attention if their weight goes up by at least 2 to 3 pounds in 24 hours, or 5 pounds or more in one week, or if they notice an increase in leg swelling and/or an increase in breathlessness.

Participants will be provided with electronic, internet connected weighing scales that can transmit weight data. These weighing scales will be used as per the usual advice given to patients, thus taking part in the study should not change their behaviour. Temporal changes in weight and volume will be compared. Research questionnaires will also be used to estimate the quality of life, mental wellbeing and hope status of participants and collect feedback on the device and study design.

Inclusion criteria

• Patients with HF who recently (<6 months) received treatment with IV diuretics for worsening congestion or outpatients with HF and peripheral oedema (any degree) treated with at least 80 mg furosemide (or equivalent)/day.
• Patients with HF ≥18 years.

• Note that the research team will try to include as many patients as possible in the month following discharge, however we will not exclude consideration of a small proportion of patients within 6 months of decompensation. This has the extra advantage of demonstrating value of the device beyond 1-2 months of decompensation.

Exclusion criteria

• Inability to provide informed consent *
• Participant has bandages to lower limbs everyday
• Participant has an amputation of the foot
• Participant is a regular wheelchair user
• Participant is of no fixed abode
• Participant has potentially reversible cause of decompensated heart failure and is awaiting urgent intervention (revascularisation/ valvular heart disease), which means the patient cannot be discharged for home-based care.
• Participant is taking part in a conflicting evaluation/study that could confound the results of this evaluation by and/or impact clinical interventions and participant outcomes.
• Participant must not be pregnant, and is taking relevant birth control if of child-bearing potential*

• Note that a participant not able to comply with weighing is NOT an exclusion criteria as the Heartfelt Device should provide data for these participants despite their lack of ability to adhere to the usual monitoring protocol, and this is seen as one of the long term benefits that the device can provide.
• Note that the exclusion criteria (a) has been added as participants would need to be able to give individual responses to questionnaires, communicate directly with the Heartfelt team, etc.
• Note that the exclusion criteria (h) has been requested by the insurance for clinical trial cover.