Inclusion Criteria: 

• 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 Criteria: 

• 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 of 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 or legal guardian/representative to give written informed consent.

• Additional factors deemed unsuitable for trial enrollment per discretion of the Principal Investigator

• Inmates

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 6/19/2025. Questions regarding updates should be directed to the study team contact.