REDUCER-I: An Observational Study of the Neovasc Reducer™ System

Inclusion Criteria - ALL Arms: * Subject has been informed about the study and provides written informed consent prior to enrollment * Subject is willing to comply with specified follow-up evaluations Inclusion Criteria - Arm 1: * Symptomatic Coronary Artery Disease (CAD) with chronic refractory angina pectoris despite attempted optimal medical therapy * Subject has limited treatment options for revascularization by Coronary Artery Bypass Grafting (CABG) or by Percutaneous Coronary Intervention (PCI) * Evidence of reversible myocardial ischemia * Left Ventricular ejection fraction (LVEF) greater than or equal to 30% * Male or non-pregnant female Inclusion Criteria - Arm 2: * Subjects previously implanted in the Reducer (treatment) arm of the COSIRA study Inclusion Criteria - Arm 3: * Subjects in whom the Reducer was implanted under CE Mark (unrelated to the COSIRA study), prior to enrollment in the Reducer-I study Exclusion Criteria - Arm 1: * Acute coronary syndrome within three months prior to enrollment * Recent successful revascularization by PCI or CABG within six months prior to enrollment * Recent unsuccessful PCI (no relief from symptoms) within 30 days prior to enrollment * Unstable angina (recent onset angina, crescendo angina, or rest angina with electrocardiogram \[ECG\] changes) during the 30 days prior to enrollment * Decompensated congestive heart failure (CHF) or hospitalization due to CHF during the three months prior to enrollment * Severe chronic obstructive pulmonary disease (COPD) as indicated by a forced expiratory volume in one second that is less than 55% of the predicted value * Subject cannot undergo exercise tolerance test * Subject cannot undergo 6-minute walk test * Severe valvular heart disease * Subject with pacemaker electrode in the coronary sinus (CS) * Subject with recent placement of a new pacemaker or defibrillator electrode in the right atrium within 3 months prior to enrollment. * Subject having undergone tricuspid valve replacement or repair * Chronic renal failure (serum creatinine \>2 mg/dL), including subjects on chronic hemodialysis * Moribund subjects, or subjects with comorbidities limiting life expectancy to less than one year * Known severe reaction to required procedural medications * Known allergy to stainless steel or nickel * Magnetic Resonance Imaging (MRI) planned within 8 weeks after Reducer implantation * Currently enrolled in another device or drug trial that has not completed the primary endpoint or that clinically interferes with the current study endpoints Angiographic Exclusion: * Mean right atrial pressure greater than 15mmHg * Subject with anomalous or abnormal CS anatomy (e.g., tortuosity, aberrant branch, persistent left superior vena cava \[SVC\]) * CS diameter at the site of planned Reducer implantation less than 9.5 mm or greater than 13 mm