Efficacy of the COronary SInus Reducer in Patients With Refractory Angina II

Inclusion Criteria: 1. Subject is older than 18 years of age 2. Symptomatic coronary artery disease (CAD) with greater than or equal to 90 days of persistent refractory angina pectoris classified as CCS Grade III or IV despite maximally tolerated guideline directed medical therapy as determined by the local heart team and confirmed by a Central Screening Eligibility Committee Note: subjects may also have exertional dyspnea, but the symptoms that limit activity must be anginal in nature (including chest pain, pressure, heaviness, discomfort, with or without radiation to the neck, jaw, shoulders, arms, or other location) and not dyspnea 3. Must have attempted treatment with the maximally tolerated dose of at least three of the four (preferably all four) approved classes of anti-anginal agents: long-acting nitrates, calcium channel blockers (either a dihydropyridine or a non-dihydropyridine), beta blockers, and ranolazine. The regimen must be stable for at least 30 days prior to enrollment, must remain stable from enrollment to randomization, and there must be no intent to change the medical regimen for at least 12 months after randomization Note: If the dose of a medication was increased or decreased for a temporary period and then returned to the original dose, which will then be continued for at least 12 months after randomization, the subject may be immediately enrolled without needing to otherwise requalify 4. Subject has either no treatment options for revascularization by coronary artery bypass grafting or by percutaneous coronary intervention, or is otherwise unsuitable or high risk for revascularization as determined by the local heart team, and confirmed by a Central Screening Eligibility Committee 5. Evidence of either exercise or pharmacologically induced reversible ischemia severity by stress echo, nuclear study, PET, perfusion MRI, CT perfusion, FFR-CT, FFR, iFR, or other non-hyperemic FDA approved tests (such as diastolic hyperaemia free ratio \[DRF\] or resting full-cycle ratio \[RFR\] in the distribution of the left coronary artery (LCA), performed within 12 months prior to enrollment Note: If the subject has evidence of ischemia in both the LCA and RCA distributions, the extent of ischemia must be greater in the LCA distribution Note: The qualifying assessment must be performed after any myocardial infarction, CABG, or successful PCI within the prior 12 months. For subjects with multiple assessments, the one performed closest to enrollment will serve as the qualifying study 6. Functional limitation due to refractory angina as defined by a modified Bruce exercise tolerance test duration of greater than or equal to 2 minutes but less than or equal to 10 minutes, performed while the subject is maintained on their stable regimen of maximally tolerated doses of anti-anginal medications Note: The ETT variability must be less than 20% between last two ETTs performed. 7. Left ventricular ejection fraction (LVEF) greater than or equal to 30% within the 12-months prior to enrollment Note: The LVEF must be reassessed after any intervening myocardial infarction. For subjects with multiple assessments, the most recent LVEF assessment is used as the qualifying test. 8. Subject is willing and able to sign informed consent 9. Subject is willing to comply with the specified follow-up evaluations Angiographic Inclusion Criteria: 1\) Three-vessel coronary angiography performed within 12 months prior to enrollment demonstrating obstructive CAD (visually estimated diameter stenosis of ≥70% or ≥50% - \<70% with fractional flow reserve (FFR) value of ≤0.80 or an iFR or other FDA-approved/cleared non-hyperemic physiological assessment (such as DFR or RFR) of ≤0.89 in one or more lesions) in the left coronary artery (main epicardial vessels or branches) that is not suitable for and will not be treated with PCI or CABG as determined by the local heart team Note: The qualifying 3-vessel angiogram must be performed after any myocardial infarction, PCI, or CABG within the 12 months prior to enrollment. For patients with multiple 3-vessel angiograms, the one performed closest to enrollment will serve as the qualifying study Exclusion Criteria: 1. Recent (within 30 days prior to enrollment) troponin or CKMB positive acute coronary syndrome (NSTEMI or STEMI) Note: subjects with an elevated troponin or CKMB without acute coronary syndrome may still be enrolled 2. Recent successful revascularization by either CABG or PCI within six months prior to enrollment Note: Successful revascularization is defined as any CABG procedure, or any PCI procedure with a reduction of one or more lesions to \<50% diameter stenosis Note: Subjects with successful revascularization by either CABG or PCI that occurred less than six months prior to enrollment may still be approved for participation in the trial if revascularization was completed six months prior to procedure and CSEC approves subject participation 3. Recent unsuccessful PCI (e.g., failed attempt to open a chronic total occlusion) within 30 days prior to enrollment Note: Subjects with unsuccessful PCI that occurred less than 30 days prior to enrollment may still be approved for participation in the trial if PCI was completed 30 days prior to procedure and CSEC approves subject participation 4. The predominant manifestation of angina is dyspnea Note: some dyspnea may be present with exertion, but the predominant symptom that limits activity must be angina (i.e., chest pain, pressure, tightness, heaviness, or discomfort, with or without radiation to the neck, jaw, shoulders, arms, or other location) 5. Has extra-coronary contributory causes of angina - e.g., untreated hyperthyroidism, untreated anemia (hgb \<10 g/dL), uncontrolled hypertension (systolic blood pressure \>160 mmHg or diastolic blood pressure \>100 mmHg despite medications), atrial fibrillation with rapid ventricular response (consistently \>100 bpm despite medications) or other ta