Feasibility and Efficacy of Coronary Sinus Narrowing in Patients With Coronary Microvascular Dysfunction

Exclusion Criteria

• •Recent (within 3 months) acute coronary syndrome
• •Patients with prior coronary artery bypass surgery
• •Unstable angina (recent onset angina, crescendo angina, or rest angina with ECG changes) during the last 30 days
• •Subjects in cardiogenic shock (systolic pressure \< 80mm/Hg, on vasopressors or intraaortic counter pulsation) at the time of consenting. Subjects who recover from cardiogenic shock by the time of consenting are eligible.
• •Obstructive CAD on coronary angiography (\>70% stenosis or 50-70% stenosis with iFR\<0.89 or FFR\<0.8 in epicardial artery)
• •Inability to perform invasive coronary flow evaluation and/or measure CFR and IMR in the LAD
• •Severe valvular heart disease
• •LVEF\<30%
• •Decompensated congestive heart failure (CHF) or hospitalization due to CHF during the last 3 months
• •Patient with a pacemaker electrode in the CS
• •Mean right atrial pressure \>15 mmHg
• •Anomalous or abnormal CS anatomy (e.g., tortuosity, aberrant branch, persistent left superior vena cava (SVC) as demonstrated on angiogram
• •CS diameter at the site of planned implantation greater than 13mm or less than 9.5 mm as measured by angiogram
• •Severe chronic obstructive pulmonary disease (COPD) indicated by a forced expiratory volume in one second that is less than 55 percent of the predicted value
• •Tricuspid valve replacement or repair (tissue or mechanical)
• •Chronic renal failure (serum creatinine \>2mg/dL), and or on chronic hemodialysis
• •Moribund, or with comorbidities limiting life expectancy to less than one year
• •Known severe reaction to required procedural medication
• •Known allergy to stainless steel or nickel
• •Magnetic Resonance Imaging (MRI) within 8 weeks of Reducer implantation
• •Participation in another ongoing investigational trial
• •Additional factors deemed unsuitable for trial enrollment per discretion of principal investigator
• •Inmates