Mitochondrial Substrate Utilization in the Diabetic Human Heart

Inclusion Criteria: * Age ≥ 20 and ≤ 85 years * Male and female patients with manifest heart failure (NYHA II-IV) and clinical indication for myocardial biopsy or after transplantation and clinical indication for myocardial biopsy with or without type II diabetes mellitus or terminal (NYHA IV) heart failure with or without type II diabetes mellitus. * Written informed consent Exclusion Criteria: * Acute infectious diseases within the last 2 weeks before the examination * Autoimmune diseases or acute immunocompromising diseases (leukocytes \< 5000/μl) * Pregnancy * Use of alcohol or drugs (addiction), psychiatric diseases * Suspected or manifest AIDS (HIV); hepatitis B or C. * Liver disease not attributed to the presence of nonalcoholic fatty liver hepatitis or congestive hepatopathy in heart failure * Malignant cancer * Lack of capacity to give informed consent or lack of consent to participate in the study * For MRI study with drug stress: contraindications to the use of regadenoson, specifically: a) Hypersensitivity to the active ingredient or any of the other ingredients mentioned. b) Second- or third-degree atrioventricular (AV) block or sinus node dysfunction, unless these patients have a functioning pacemaker. c) Unstable angina that has not been stabilized with medication. d) Severe hypotension. e) Decompensated stages of heart failure.