This study will evaluate the feasibility and safety of achieving therapeutic concentrations of beta-hydroxybutyrate using continuous infusion of D-beta-hydroxybutyrate monoester administered via a nasogastric tube in patients with acutely decompensated heart failure with reduced left ventricular ejection fraction.

Adult patients with left ventricular ejection fraction (LVEF) <35% admitted to the intensive care unit for acutely decompensated heart failure with low cardiac output syndrome or cardiogenic shock will receive a continuous infusion of D-3-hydroxybutyrate (3-OHB) monoester via a nasogastric tube for 36 hours. The infusion rate will be iteratively adjusted to achieve an arterial blood concentration of 3-OHB of 2-3.5 mmol/L. Arterial blood concentrations of 3-OHB will be measured every 1-3 hours using point-of-care testing. The primary endpoint will be the proportion of time within the target concentration range. Secondary safety endpoints will include worsening of liver function not attributable to hemodynamic deterioration, occurrence of cardiac arrhythmias, and gastrointestinal tolerance of the infusion.

Inclusion Criteria:

• LVEF <35%
• Acute heart failure with low cardiac output syndrome or cardiogenic shock

Exclusion Criteria:

• Severe liver failure
• Severe acidosis
• Inability to insert nasogastric tube
• Gastric paralysis / ileus
• Repeated vomiting
• Severe hypokalemia