CardioMEMS HF System Post Approval Study

Inclusion Criteria: * Diagnosis of NYHA class III heart failure * At least 1 heart failure hospitalization within previous 12 months * Patients with reduced LVEF heart failure should be receiving a beta blocker for 3 months and an ACE-I or ARB for one month unless in the investigator's opinion, the patient is intolerant to beta blockers, ACE-I or ARB * BMI ≤ 35. Patients with BMI \>35 will require their chest circumference to be measured at the axillary level. If \> 65 inches the patient will not be eligible for the study. * Pulmonary artery branch diameter ≥ 7mm - (implant target artery - assessed during the right heart catheterization) Exclusion Criteria: * Active infection * History of recurrent (\> 1) pulmonary embolism or deep vein thrombosis * Inability to tolerate a right heart catheterization * A major cardiovascular event (e.g., myocardial infarction, open heart surgery, stroke, etc.) within previous 2 months * Cardiac resynchronization device (CRT) implanted within previous 3 months * Glomerular Filtration Rate (GFR) \< 25 ml/min (obtained within 2 weeks of implant) who are non-responsive to diuretic therapy or who are on chronic renal dialysis * Congenital heart disease or mechanical right heart valve * Likely to undergo heart transplantation or VAD within the next 6 months * Known coagulation disorders * Hypersensitivity or allergy to aspirin, and/or clopidogrel