Coronary Sinus Reducer for Symptomatic Heart Failure with Preserved Ejection Fraction and Coronary Microvascular Dysfunction Treatment

Study start date: October 16, 2025

Inclusion: * Age ≥ 18 * Able to provide written informed consent and willing to participate in all required study follow-up assessments * Clinical indicated coronary angiography with invasive CRT testing within 6 months prior to enrollment. Abnormal CFR of ≤ 2.5 * Symptomatic HFpEF defined by (PAWP\>15mmHg at rest and /or PAWP\>25 mmHg on exertion) during clinically performed Right heat catheterization with exercise performed within 6 months of enrollment or during screening visit (if not performed clinically in the last 6 months). * Non-Obstructive CAD (≤ 50% stenosis in epicardial vessels and/or iFR\>0.89 or FFR\>0.8 in vessels with 50 to 70% stenosis) Exclusion: * History of left ventricular (LV) ejection fraction \<50% * Significant epicardial CAD (angiographic stenosis ≥70% or positive FFR or iFR in any major epicardial coronary artery * Significant valvular heart disease (more than moderate regurgitation and or stenosis) * Primary cardiomyopathies (hypertrophic, infiltrative or restrictive) * Constrictive pericarditis * Severe myocardial bridging * Stiff left atrial syndrome * Pregnancy * Recent (with 3 months) acute coronary syndrome * Subjects in Cardiogenic shock (systolic pressure\<80mm/Hg) * NYHA Class III or IV heart failure decompensated HF * Mean right atrial pressure at rest \>15 mmHg * Anomalous or abnormal CS anatomy (e.g. tortuosity aberrant branch persistent left superior vena cava 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. * Known severe reaction to required procedural medications * Known allergy to stainless steel or nickel * Magnetic Resonance Imaging (MRI) within 8 weeks after Reducer implantation * Chronic renal failure (serum creatinine\>2mg/dL) * Severe chronic obstructive pulmonary disease (COPD) as indicated by forced expiratory volume in one second that is less than 55% of the predicted value or need for home daytime oxygen * Pacemaker electrode/lead in the coronary sinus * Moribund or with comorbidities limiting life expectancy to less than one year * Current or past participation within a specified timeframe in another clinical trial, as warranted by the administration of this intervention. * Inability or unwillingness of individual to give written informed consent. * Additional factors deemed unsuitable for trial enrollment per discretion of the Principal Investigator * Inmates