CoROnary SinuS Reducer implantatiOn for ischemiA reDuction

Patients with refractory angina pectoris have low quality of life and reduced exertional capacity. Studies have shown that the coronary sinus reducer (CSR) implantation improves the quality of life. However, to date there are no firm objective data on improvement of exertional capacity. Studies have shown a large influence of placebo effect after interventional procedures, which is even more pronounced than in medically treated patients. As angina pectoris presents entirely subjective perception of chest discomfort, its improvement may be influenced by this effect in up to 30 %. The investigators will study weather the CSR implantation improves aerobic exertional capacity in comparison to optimal medical therapy alone. Further, the investigators will explore the extent of myocardial reversible ischemia reduction and possible influence on hrECG markers of left ventricular arrhythmogenicity. 40 patients with refractory angina CCS class (Canadian cardiovascular society) II-IV and confirmed reversible ischemia will be included. Patients will be randomized into two groups. The first group will undergo CSR implantation procedure. The second group will present a sham control group with placebo procedure. At inclusion and after 6 months the investigators will perform cardiopulmonary exercise test (CPET), single photon emission tomography for detection of reversible ischemia (SPECT), high resolution ECG (hrECG), echocardiography and asses the subjective burden of angina according to CCS score and the quality of life according to the Seattle angina Questionnaire (SAQ).