The objective of the RELIEVE-HF study is to provide reasonable assurance of safety and effectiveness of the V-Wave Interatrial Shunt System by improving meaningful clinical outcomes in patients with New York Heart Association (NYHA) functional Class II, Class III, or ambulatory Class IV heart failure (HF), irrespective of left ventricular ejection fraction, who at baseline are treated with guideline-directed drug and device therapies.

This is a prospective, multi-center, 1:1 randomized, patient and observer blinded clinical study, with a Shunt Treatment arm and a non-implant Control arm. A total of approximately 500 patients will be randomized. Patients and all research staff managing the patients after randomization will be blinded during follow-up for a minimum of 12 months to a maximum of 24 months. Control patients will have the opportunity to receive a shunt after 24 months once unblinding occurs, if they provide consent, and continue to meet inclusion/exclusion criteria. All implanted patients will be followed for a total of 5 years from the time of the study device implantation.

Main Inclusion Criteria:

• Both heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF) patients
• NYHA Class II, Class III, or ambulatory Class IV HF
• Receiving guideline directed medical and device therapy (GDMT) for heart failure
• For NYHA Class III and ambulatory Class IV, at least one prior hospitalization for heart failure within the last year or elevated BNP level of at least 300 pg/ml or NT-proBNP level of at least 1,500 pg/ml. BNP/NT-ProBNP levels corrected for BMI
• For NYHA Class II, must have both hospitalization and elevated BNP levels as above specifications

Main Exclusion Criteria:

• Systolic blood pressure <90 or >160 mmHg
• Presence of Intracardiac thrombus
• Pulmonary hypertension with PASP of ≥70 mm/Hg or PVR > 4 WU
• Significant RV dysfunction - TAPSE <12mm or RVFAC ≤25%
• Left Ventricular End-Diastolic Diameter (LVEDD) >8cm
• Moderate to severe aortic or mitral stenosis
• Stroke or TIA or DVT within the last 6 months
• eGFR <25 ml/min/1.73 m^2
• Anatomical anomaly on TEE or ICE that precludes implantation of Shunt across fossa ovalis (FO) of the interatrial septum
• Inadequate vascular access for implantation of shunt, e.g. femoral venous access for transseptal catheterization and inferior vena cava (IVC) is not patent
• Hemodynamic heart rhythm, or respiratory instability at time of Final Exclusion Criteria

In the randomized cohort, participants, the clinical team, and research staff managing the patient after randomization will be blinded to study assignment.