The purpose of this study is to establish an electrocardiogram (ECG) data library to facilitate future studies on heart disease. Additionally, the study will be used to monitor changes in the patient's standard of care throughout the study period and gather patient perspectives on routine diagnostic procedures and disease monitoring and feedback on the design of heart failure trials.

Patients with heart failure with mildly reduced or preserved ejection fraction will be invited to participate in this patient observational study.

After providing informed consent, participants will then undergo a series of clinical assessments, and the participants' ECGs will be used to contribute to establishing an ECG library for future heart disease research. Additionally, patients' perspectives on the current standard of care clinical procedures will be gathered. Patient preferences will be gathered in relation to factors around routine clinical investigations for heart failure to better design a disease monitoring tool to include clinical and patient preferences. Also, the patients may be updated on the latest therapy options.

Additionally, participants may be invited to review and provide feedback on the study design of heart failure trials under development, helping to ensure alignment with patient needs. Their input can identify potential procedure challenges and enhance the clarity of study materials, improving overall patient engagement. A follow-up call with a research physician will provide the opportunity to discuss any issues identified in the clinical baseline assessment and allow the participant to ask any additional questions.

Inclusion Criteria:

1. Male or female participants aged 45 to 80 years (inclusive) at the date of signing the informed consent.
2. Diagnosed with heart failure.
3. Able and willing to provide informed consent to participate.

Exclusion Criteria:

1. Diagnostic test results positive for:

   1. HIV-1 or HIV-2 infection
   2. Hepatitis B or Hepatitis C infection

2. Mental incapacity, language barriers or unwillingness to comply with the requirements of the protocol, which may preclude adequate understanding or cooperation during the study as judged by the Investigator.

3. Any condition judged by the Investigator to pose an undue risk while participating in the trial

4. Diagnostic results which are inconsistent with heart failure with mildly reduced or preserved ejection fraction as judged by the Investigator.

General public who meet the inclusion/exclusion criteria

Study publication when completed