Inclusion Criteria:

• Age ≥ 30 years
• Symptoms of severe dyspnea (NYHA Class III-IV) without evidence of a non-cardiac or ischemic explanation for dyspnea
• Ejection fraction of ≥50%, determined on most recent imaging study within the preceding 2 years (730 days), with no change in clinical status, suggesting potential for deterioration in systolic function.
• Documentation history of at least one of the following:
  • Any previous hospitalization for HF (>30 days prior to enrollment) with radiographic evidence of pulmonary congestion (pulmonary venous hypertension, vascular congestion, interstitial edema, pleural effusion) or
  • Elevated NT-proBNP (>300 pg/ml or >600 pg/ml if in atrial fibrillation) or
  • Echocardiographic evidence of diastolic dysfunction/elevated filling pressures manifested by medial E/e’ ratio ≥15 and/or left atrial enlargement and chronic treatment with a diuretic for signs or symptoms of heart failure or
  • Historical catheterization documented elevated filling pressures at rest (PCWP ≥15 or LVEDP ≥18) or with exercise (PCWP ≥25), prior to consent.
• Catheterization documented elevated filling pressures at rest (PCWP ≥15 or LVEDP ≥18) or with exercise (PCWP ≥25) during the screening/baseline visit (after consent)
• Ambulatory with ability to complete 6-minute walk and cardiopulmonary exercise test (not wheelchair / scooter dependent)

Exclusion Criteria:

• Recent (< 30 days) hospitalization for heart failure
• Left (> 6 cm) ventricular dilation noted on cardiac imaging study (echocardiography or MRI) within 6 months prior to enrollment.
• Any hemoglobin (Hgb) < 8.0 g/dl within 30 days prior to enrollment
• Any GFR < 20 ml/min/1.73 m2 within 30 days prior to enrollment
• Significant alternative cause of dyspnea such as severe chronic obstructive pulmonary disease or ischemia that is a primary contributor to symptoms, in the opinion of the Investigator.
• Myocardial infarction (MI), unstable angina, catheter ablation for atrial fibrillation, biventricular pacing device implant, or percutaneous coronary intervention (PCI) within 90 days prior to enrollment
• Any prior cardiac surgery
• Documented stroke, CVA, TIA, deep vein thrombosis, pulmonary emboli, or suspected neurological event within 180 days prior to enrollment
• Diagnosis of obstructive hypertrophic cardiomyopathy
• Known infiltrative cardiomyopathy (e.g., amyloid)
• Known pericardial disease (constriction, pericarditis, tamponade)
• . Known allergy or sensitivity to contrast media that cannot be adequately pre-treated prior to the procedure.
• Active myocarditis
• Significant congenital anomaly, anatomic, or comorbid medical problem that, in the opinion of the Investigator, would preclude enrollment in the study.
• Active collagen vascular disease
• Significant valvular heart disease (greater than mild stenosis or greater than moderate regurgitant lesions)
• Acute or chronic severe liver disease, as evidenced by any of the following: encephalopathy, variceal bleeding, INR > 1.7 in the absence of anticoagulation treatment.
• Untreated severe obstructive sleep apnea (if known)
• Implantation or planned implantation of any left atrial shunts or implantable devices used to treat heart failure.
• Terminal illness (other than HF) with expected survival of less than 1 year
• Enrollment or planned enrollment in another therapeutic clinical trial in the next 6 months.
• Inability to comply with planned study procedures or follow-up requirements, including cardiac MRI (e.g., claustrophobia or absolute contraindication to MRI)
•  Women who are currently pregnant, plan to become pregnant, or are currently breastfeeding.
• Intolerance or contraindication to colchicine

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 4/25/2024. Questions regarding updates should be directed to the study team contact.