Coronary Sinus Reducer Therapy for Persisting Angina

Inclusion Criteria: * Angina - Canadian Cardiovascular Society Class II-IV on at least two anti-anginals or maximally tolerated medical therapy if less than two.Hemodynamically significant epicardial coronary artery disease in the LAD, defined as an FFR≤0.80 and/or NHPR≤0.89. * No conventional revascularization options or considered unsuitable as determined by the local heart team. * Anatomically suitable for instrumentation of the left anterior descending coronary artery with a coronary pressure wire and infusion microcatheter. * Patient understands the nature of the procedure and provides written informed consent for the study prior to enrolment. Exclusion Criteria: * Age \< 18 years. * Absence of symptoms reported on the ORBITA-app during the 2-week screening period. * Mean right atrial pressure ≥15 mmHg * Severe pulmonary hypertension. * Coronary sinus anatomy not suitable for CSR implantation. * Pregnancy or planned pregnancy within the next 12 months. * Recent acute coronary syndrome (within 3 months). * Recent revascularization with PCI (within 6 months). * Severe arrhythmias, including chronic atrial fibrillation with persistent rapid ventricular response (\>100bpm despite medication). * Indication for cardiac resynchronization therapy. * Severe left ventricular impairment (left ventricular ejection fraction \<30%). * NYHA class IV or decompensated heart failure or hospitalization due to heart failure within 90 days before the index procedure. * Recent implantation…