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
