This is an early feasibility study to evaluate initial safety, device practicality, and performance of the Edwards Transcatheter Atrial Shunt System (study device) in subjects with heart failure. The Edwards Transcatheter Atrial Shunt System is intended for transcatheter treatment of symptomatic left heart failure patients. The Atrial Shunt opens a channel for blood to flow from the higher pressure left atrium to the lower pressure right atrium via the coronary sinus.

Major study activities include 3 right heart catheterizations (RHC) with exercise, a computed tomography (CT) scan with contrast, multiple ultrasounds of the heart, labs, and other assessments. The length of subject participation in the study is 5 years and includes 11 research visits.

The most common risks associated with the research procedure are those related to the right heart catheterization (RHC) and implant procedure. There are no known benefits of the research device. There may be possible benefits from the research procedure including improvement in quality of life or a decrease in the symptoms caused by heart failure.

The information obtained from this study will show how safe and effective this approach is in treating the symptoms of heart failure. Alternative treatment for heart failure depends on the cause, but may include diet and exercise, managing stress, medication (such as medications to treat leg swelling, high blood pressure, or abnormal heart rate), participation in another research study or continuing with current medical therapy.