A Study Of CS Reducer For Symptomatic Heart Failure With HFpEF And CMD

This study is looking at the use of a device called a CS Reducer for people with a type of heart failure where the heart muscle pumps normally but the heart is too stiff (called heart failure with preserved ejection fraction, or HFpEF) combined with a condition where blood supply to the heart muscle is reduced (called coronary microvascular dysfunction, or CMD). This is a sub-study using MRI imaging to better understand how the device affects the heart. **You may be eligible if...** - You are 18 years or older - You are already enrolled in the main CS-Reducer HFpEF clinical study at the same institution **You may NOT be eligible if...** - You have metal implants in your body that are not safe for MRI scans - You are unwilling or unable to give written informed consent Talk to your doctor to see if this trial is right for you.