The aim of the study is to provide information on the interaction between socioeconomic factors, daily physical activity, nutrition and lifestyle on loss of muscle mass and muscle function in patients with heart failure.

A total of 200 consecutive heart failure patients will be included and 50 age and sex-matched individuals with no history of cardiovascular disease will serve as controls.

Baseline variables of body composition, physical capacity, daily physical activity, nutritional status, quality of life, socioeconomic status and insulin resistance will be obtained along with a skeletal muscle tissue biopsy and blood samples for laboratory analyses.

Baseline variables from heart failure patients will be compared to healthy controls.

Patients and controls will be invited to follow-up visits at 12 and 36 months. Changes in baseline variables will be analyzed.

Events will be identified through national registries.

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.

A total of 200 consecutive heart failure patients will be included and 50 age and sex matched individuals with no history of cardiovascular disease will serve as controls.