Safety and Efficacy of Induced Pluripotent Stem Cell-derived Engineered Human Myocardium as Biological Ventricular Assist Tissue in Terminal Heart Failure

Inclusion Criteria: 1. Symptomatic heart failure (NYHA II-IV) with reduced ejection fraction (HFrEF with LVEF ≤35%) as assessed by echocardiography. 2. Patients on guideline-directed medical therapy 3. NT-proBNP \>300 pg/mL for patients in sinus rhythm or \>900 pg/mL if in atrial fibrillation 4. History of previous heart failure hospitalization in the past 12 months 5. At least one hypo- or dyskinetic segment or dilated heart chamber to demark the implant target area 6. (A) Stable disease condition allowing for an elective left-lateral mini-thoracotomy (for LV applications) or (B) open-chest surgery (for RV applications) for a clinically indicated intervention on the LV (e.g., coronary bypass surgery, valve repair, mechanical circulatory support device implantation) with concomitant RV dysfunction, diagnosed using the Tricuspid Annular Plane Systolic Excursion (TAPSE) index \<16 mm (Rudski et al. 2010). 7. 18-80 years of age 8. Willingness and ability to give written informed consent 9. Female subjects of childbearing potential must agree to use acceptable method(s) of contraception for the full study duration. Exclusion Criteria: 1. Contraindication to immunosuppressive drugs (e.g. known history of unresolved cancer, hepatitis B/C, HIV, HTLV1) 2. Contraindication to TachoSil® (e.g. hypersensitivity to human fibrinogen, human thrombin, horse collagen, human albumin, Riboflavin, Natriumchloride, Natriumcitrate, L-Arginin-Hydrochloride) 3. Hypertrophic cardiomyopathy (HCM) 4. Terminal kidney failure (stage 4; GFR \<30 ml/min) at the time of enrolment 5. Terminal liver failure (Child-Pugh stage C; score \>10) at the time of enrolment 6. History of disabling stroke 7. Reduced life expectancy in the short term due to non-cardiac disease 8. Any condition that excludes adherence to study protocol (in particular lack of adherence to prescribed medication) 9. Simultaneous participation in another interventional trial 10. Pregnant or breastfeeding females 11. Known or suspected alcohol and/or drug abuse