The investigation will enroll subjects who have been previously implanted with the CardioMEMS™ Pulmonary Artery Sensor. This clinical investigation is twofold; in the first phase (development phase) data collected will be used to complete development of an algorithm that can estimate cardiac output from CardioMEMS™ Heart Failure (HF) System readings. The second phase (validation phase) of this clinical investigation is intended to compare the Cardiac Output estimate from CardioMEMS HF System to Cardiac Output estimates from Cardiac Magnetic Resonance Imaging (reference standard).

Inclusion Criteria:

1. Subject is willing and able to provide written informed consent prior to any clinical investigation-related procedure.

2. Subject is implanted with the CardioMEMS Pulmonary Artery Sensor for a minimum of 3 months at time of consent.

3. Subject is ≥ 18 years of age.

4. Subject is willing and able to undergo several cardiac Magnetic Resonance Imaging scans. This is including but not limited to:

   • Subject must have all Magnetic Resonance Imaging compatible devices
   • Subject must be able to hold their breath during imaging
   • Subject must be free of all metal bodies, fragments, or implants that would prohibit Magnetic Resonance imaging

5. Subject is willing and able to upload Pulmonary Artery pressure information (i.e., take daily CardioMEMS readings and have their hemodynamic information collected at study visits) and comply with the follow-up requirements.

Exclusion Criteria:

1. Subject will receive or is likely to receive an advanced therapy (e.g., mechanical circulatory support or cardiac transplant) in the next 6 months.
2. Subject was implanted with Cardiac Resynchronization Therapy (CRT)-Pacemaker (CRT-P) or CRT-Defibrillator (CRT-D) for less than 90 days prior to consent.
3. Subject is pregnant or planning to become pregnant in the next 6 months.
4. Subject is enrolled into another trial with an active treatment arm.
5. Subject has significant congenital heart disease that has not been repaired.
6. Subject is implanted with mechanical right heart valve(s).
7. Subject has unrepaired severe valvular disease.
8. Subject has an anticipated life expectancy of < 6 months.
9. Subject has an active, ongoing infection, defined as being febrile, an elevated white blood cell count, on intravenous antibiotics, and/or positive cultures (blood, sputum, or urine).
10. Subject has had a major cardiovascular event (e.g., unstable angina, myocardial infarction, percutaneous coronary intervention, open heart surgery, or stroke, etc.) within 90 days prior to consent.
11. Subject has any condition that, in the opinion of the Investigator, would not allow for utilization of the CardioMEMS HF System to manage the subject using information gained from hemodynamic measurements to adjust medications, including the presence of unexpectedly severe pulmonary hypertension (e.g., trans-pulmonary gradient >15) at implant Right Heart Catheterization, a history of non-compliance, or any condition that would preclude ability to obtain CardioMEMS Pulmonary Artery Sensor readings and paired cardiac Magnetic Resonance Imaging data from being collected.
12. Subjects who, in the opinion of the investigator, are at-risk for serious adverse reaction to Dobutamine (ex. subjects with idiopathic hypertrophic subaortic stenosis and subjects who have shown previous manifestations of hypersensitivity to Dobutamine) should be excluded from the study.

This clinical investigation will enroll subjects of all genders who are ≥ 18 years of age from the CardioMEMS HF System patient population. The patient population for this clinical trial consists of potential subjects who have had a CardioMEMS PA Sensor previously implanted for a minimum of 3 months at time of consent.