Atrial Flow Regulator in Heart Failure

Inclusion Criteria: * Age ≥ 18 years * Symptomatic heart failure (HF) in NYHA class III or IV ambulatory * Optimal medical therapy of HF according to European Society of Cardiology (ESC) guidelines for last 6 months * Hospitalization because of HF decompensation in last 12 months * Absence of significant valvular disease requiring cardiac surgery * Life expectancy ≥ 1 year * Written informed consent obtained from the patient * Left ventricle ejection fraction (LVEF) ≥ 15% * Elevated left heart filling pressures: 1. Pulmonary artery wedge pressure (PAWP) at rest \> 15 mmHg or 2. PAWP \> 25 mmHg during hand grip test Exclusion Criteria: * Participation in another clinical trial in last 30 days * Acute infection or sepsis * Severe coagulation disorder * Allergy to nickel or titanium * Severe peripheral artery disease disabling 6 minutes walk test * Allergy to antiplatelet drugs, oral anticoagulants or heparin * Contraindication to trans-oesophageal echocardiography (TEE) * Pregnancy * Atrial septal defect (ASD) or presence of atrial septal occluder * Severe patent foramen ovale (PFO) with significant left to right shunt in rest * Intracardiac thrombus * Acute coronary syndrome or Percutaneous Coronary Intervention (PCI) or Coronary Artery Bypass Grafting (CABG) in last 6 months * Severe pulmonary hypertension: 1. Right atrial pressure ≥ PAWP (measured in right heart catheterization) 2. Right atrial pressure \> 20 mmHg (measured in right heart catheterization) * Planned heart transplantation * Transient ischemic attack or stroke within last 6 months * Cardiac resynchronisation therapy (CRT) within last 6 months