Heart failure is a severe heart disease, where the heart's ability to pump blood is unsatisfactory. The consequence is a high risk of hospitalization and death. Heart failure is treated with medicine which relieves symptoms and slows down the disease progression. This medical treatment needs routine adjustment, but in many cases, this adjustment is not done timely, which results in life treating conditions where the patients need acute hospitalization. Remote health monitoring of HF patients has the potential to ensure timely adjustment. However, only sensors placed inside the blood vessels of the lung, have been shown effective. The disadvantage is that the placement of the sensor requires surgery. This makes the method costly and poses a risk for the patient. The aim of the current project is to develop a small intelligent patch, which can measure the heart's function from the outside of the body. The method will be low-cost, simple to use and will not pose a risk to the patient.

The goal of this observational study is to gather data from heart failure participants, and to investigate whether it is possible to detect early alterations in heart failure based on this data. The main goals are

• Investigate whether parameters extracted from the measured data provide information regarding heart failure alterations
• Investigate if it is possible to detect alterations at early stages

The gathered data will be measured from a little sensor placed on sternum measuring acceleration (seismocardiography (SCG)) and electrocardiography (ECG) to provide an impression of the heart's mechanical function and electrical function, respectively. This data from the sensor will be analyzed with respect to other parameters obtained from, among others, echocardiography, total blood volume, changes in medical therapy, and hospitalization.

The included heart failure participants should be in the age group 18-90 years and in New York Heart Association Functional Classification (NYHA) class II or higher. Participants will wear the sensor to measure the participant's cardiac mechanics and electronics simultaneously. The participants will:

• wear the sensor for a period of 30 days from discharge or visit to heart failure clinic. The sensor will measure SCG and ECG for a short period (less than 30 seconds) once every hour,
• fill out questionnaires at first and last day of the study
• undergo echocardiography at first day and last day of the study
• not change everyday life because of the sensor

Inclusion Criteria:

• NYHA Class II or higher
• 18-90 years old

Exclusion Criteria:

• Pregnancy
• Drug addiction defined as the use of cannabis, opioids, or other drugs
• Mechanical heart valves
• In dialysis
• Not possible to obtain clinical echocardiography of sufficient quality
• Lack of ability to coorperate

The participants will be obtained from Aalborg University Hospital or Herlev-Gentofte Hospital in Denmark that are hospitalized or visits the heart failure clinic due to their heart failure.