Mechanism of Sarcopenia in Heart Failure

Inclusion Criteria: 1. Ability to provide valid informed consent. 2. Heart failure with preserved, mid-range or reduced ejection fraction (NYHA I-IV) according to European Society of Cardiology guidelines. Exclusion Criteria: 1. Cancer requiring treatment (e.g. prostate cancer on watchful waiting does not exclude patients). 2. Severe musculoskeletal or neurological disability. 3. Severe lung disease with a forced expiratory volume 1 \< 40% of predicted. Treatment with anticoagulants (warfarin, apixaban, edoxaban, dabigatran and rivaroxaban) is an exclusion criterion for muscle biopsy. Patients with anticoagulant treatment will be invited to participate in the study without muscle biopsy. 4. Other comorbidities that prevent the patient from participating in the study examinations as judged by the investigator.