Successful implantation of cardiac resynchronization therapy in a patient with coronary sinus reducer using proximal coronary sinus branches: a case report.

Background: The coronary sinus reducer (CSR) is a therapeutic option for patients with coronary artery disease who are not eligible for further revascularization and experience refractory angina. Cardiac resynchronization therapy (CRT) improves symptoms and prognosis in heart failure with reduced ejection fraction, but the presence of a CSR may complicate left ventricular lead placement. Only four cases have been reported so far in this context. This case report introduces a novel technique for left ventricular lead implantation in such patients.

Case summary: A 73-year-old man with a history of chronic coronary syndrome, coronary artery bypass surgery, angioplasties, and CSR implantation presented with heart failure symptoms. His ECG showed sinus rhythm and left bundle branch block (QRS 160 ms), and echocardiography revealed severe systolic dysfunction (ejection fraction 20%). During Cardiac Resynchronization Therapy-Defibrillator (CRT-D) implantation, venography revealed a suitable proximal tributary branch near the CSR, which was successfully used for lead placement without complications.

Discussion: The CSR has shown promise in relieving refractory angina. As ischaemic heart disease progresses, CRT may become necessary in patients with CSR. The CSR's design can reduce the vascular lumen and complicate lead placement. Previous reports have confirmed the technical feasibility of CRT with CSR but lack long-term safety data. This case highlights that, under favourable anatomical conditions, proximal tributaries of the coronary sinus can be used for lead placement, potentially avoiding complications from reduced venous outflow.