BIO-2-HEART: Identification of Biomarkers in T2DM and Heart Failure

Inclusion Criteria: 1. guideline-appropriate clinical indication for CRT implantation/electrophysiologial examination/pulmonary vein ablation 2. age of majority 3. written declaration of consent 4. persons who are able to work and mentally able to follow the instructions of the study staff 5. free access routes Exclusion Criteria: 1. anemia Hb \<8 mg / dl 2. patients with acute infectious disease (e.g. pneumonia) 3. non-intubatable coronary sinus 4. patients who do not have access to the subclavian vein (e.g. thrombosis of the subclavian vein or superior vena cava) 5. patients with idiopathic hypertrophic, restrictive or constrictive cardiomyopathy, or heart failure due to a known inflammatory or infiltrating disease (e.g. amyloidosis, sarcoidosis) or a constrictive disease 6. patients with heart failure by sepsis 7. persons with acute myocardial ischaemia, e.g. by angina pectoris or ECG changes under load 8. patients with acute coronary syndrome are not implanted in the past 3 months 9. patients who were hospitalized during the last month due to heart failure and who had to be treated intravenously with diuretics or inotropic substances 10. patients with mechanical aortic valve or tricuspid valve 11. patients with heart transplant. 12. patients with acute liver or renal failure 13. pregnant and lactating women 14. patients placed under an official or judicial order in an institution 15. patients who are in a dependency or employment relationship with the sponsor or auditor 16. taking an investigational medicinal product 30 days before the start of the study