Ketogenic Diet vs Mixed Diet in Patients With Heart Failure

Inclusion criteria

• Age ≥ 18 years old and ≤ 80 years old \& willingness to be randomized to either diet.
• NYHA class I - III for at least 3 months.
• Ejection fraction ≥40% by biplane 2D, or 3D echo, or CMR
• Echo findings of abnormal or indeterminant diastolic function or right heart catheterization (RHC) data: At rest: mean pulmonary capillary wedge pressure (PCWP) \> 15 mmHg. pulmonary vascular resistance (PVR) \< 3 Wood Units.
• Stable medical therapy for at least 3 months as determined by the treating physician (no new cardiac or diabetic medications within 3 months of enrollment or during enrollment and dosage should be stable for 1 month prior to enrollment).
• Dose of oral diuretics changes allowed but must be stable for 1 week prior to randomization.
• Body Mass Index (BMI) ≥ 25 or Type 2 Diabetes Mellitus or prediabetes (fasting glucose of 100 - 125 mg/dL or glycated hemoglobin (A1C) 5.7-6.4% or metabolic syndrome.
• Ability to participate in exercise treadmill testing.
• Ability to sign written consent.

Exclusion criteria

• Women who are pregnant, current breast-feeding, or have intention to become pregnant while in the study.
• Known allergy or sensitivity to gadolinium-based contrast agents.
• Implanted pacemaker, cardioverter defibrillator, Cardiac resynchronization therapy, left ventricular assist device.
• Other metallic implants/aneurysm clips that are contraindicated in MRI.
• Claustrophobia
• History of severe kidney disease of estimated glomerular filtration rate (eGFR) \<30 ml/kg/1.73m2.
• Type I diabetes.
• History of diabetic ketoacidosis.
• Prior diagnosis of oxygen dependent pulmonary disease.
• Body Mass Index (BMI) \< 25.
• Recent acute myocardial infarction or acute coronary syndrome (30 days).
• Or recent (within 30 days) or planned (within 30 days) cardiac revascularization History of left main disease, severe triple vessel disease, coronary artery bypass graft surgery.
• Left ventricular ejection fraction \< 50%.
• Uncontrolled systemic systolic blood pressure (SBP)/diastolic blood pressure (DBP) hypertension (SBP \>180 or DBP \>110 mmHg).
• Severe stenotic or regurgitant valvular heart disease, expected to lead to surgery during the study period.
• Persistent atrial fibrillation.
• History of uncontrolled or untreated ventricular arrhythmias.
• Cardiovascular diseases or treatments that increase the unpredictability of or change the subject's clinical course, independent of heart failure.
• Heart transplant or listing for heart transplant.
• Cardiomyopathy based on infiltrative diseases (e.g. amyloidosis), accumulation diseases (e.g. haemochromatosis, Fabry disease), muscular dystrophies, cardiomyopathy with reversible causes (e.g. stress cardiomyopathy), hypertrophic obstructive cardiomyopathy or known pericardial constriction.
• Acute decompensated heart failure requiring intravenous diuretics, vasodilators, inotropic agents or mechanical support within 1 week of screening and during the screening period prior to randomization.
• Hemoglobin of \<9 g/dL at screening.
• Major surgery (major according to the investigator's assessment) performed within 90 days prior to screening, or major scheduled elective surgery (e.g. hip replacement) within 90 days after screening.
• Acute or chronic liver disease, defined by serum levels of transaminases or alkaline phosphatase more than three times the upper limit of normal at screening.
• Gastrointestinal surgery or gastrointestinal disorder that might interfere with diet. Prior bariatric surgery allowed if weight-stable for past 3 months.
• Any documented active or suspected malignancy or history of malignancy within 2 years prior to screening, except appropriately treated basal cell carcinoma of the skin, in situ carcinoma of the uterine cervix, or low-risk prostate cancer (subjects with pre-treatment prostate-specific antigen levels of \<10 ng/mL, and biopsy Gleason scores of ≤6 and clinical stage T1c or T2a).
• Presence of any disease other than heart failure that results in a life expectancy of \<1 year (in the opinion of the investigator).
• History or recurrent severe hypokalemia, potassium \< 3.0 mg/dL.
• Current enrollment or completion within 30 days of an investigational device or drug study.
• Chronic alcohol or drug abuse or any condition that, in the investigator's opinion, will make the subject unlikely to fulfill the study requirements or complete the trial.
• Any other clinical condition that might jeopardize subject safety during participation in this study or prevent the subject from adhering to the study protocol.
• Unable or unwilling to follow guidelines of assigned diet group, including inability to purchase food.
• Unable to participate in the comprehensive diet program, including biometric data acquisition and data entry.
• The subject cannot currently be on a low-carb diet plan. 30-day washout would be required.
• Patient has to have stable weight over the past 3 months (± 5% total body weight). If no weight was recorded in the past 3 months, will have 1 month lead in time for wash out.
• Refusal to consent.