50 patients will have access to a mobile phone application for 3 months.

The application will contain the following modules:

1. information and knowledge about heart failure;
2. vital sign diary, which can be sent to the certified HFU
3. pedometer (individualized step-goal), cardiac home training videos
4. "frequently asked questions" and connection to a certified HFU provider by a heart failure hotline

The acceptence of the application will be measured by the User Experience Questionnaire. It consists of 9 items that can be rated on a 7-point Likert scale. -3 (fully agree with negative term) to +3 (fully agree with positive term). A higher total score means a better outcome.

Quality of life measured by Kansas City Cardiomyopathy Questionnaire using the validated 12-item version which has been described by Spertus et Jones (doi: 10.1161/CIRCOUTCOMES.115.001958.) A higher score means a better outcome.

Health-related quality of life will be measured by the "Patient Related Outcome and Measurement Information System" (PROMIS) test. Including 23 items that will be analyzed via Likert scale 1 (impossible/never) to 5 (no limitations/very good). A higher score means a better outcome.

Symptoms of heart failure will be assessed by the New York Heart Association functional class. Consisting of four classes (I-IV), the higher, the worse the outcome.

Functional capacity will be assessed by the 6-minute walk test

Functional capacity will be assessed by the steps taken within 24 hours (pedometry).