Treatment With the Ketone Body 3-hydroxybutyrate in Patients With Acute Heart Failure

Inclusion Criteria: * Hospitalized with worsening HF or de novo diagnosis of HF * LVEF \< 50% * Treatment with intravenous loop diuretics during the hospitalization and/or increased dosage of oral diuretics. Exclusion Criteria: * Cardiogenic shock * Systolic Blood Pressure \<85 mmHg * Acute myocardial infarction other than type II \<5 days prior to randomization \* * Severe uncorrected cardiac valve disease * Expected or possible need for hemodialysis as judged by the investigator * Ongoing inotropic treatment * Possible need for advanced heart failure treatment (LVAD, heart transplantation) as judged by the investigator. * Ongoing, severe infection * Severe respiratory distress (SAT\<90% or RF\> 24/min or receiving more than 2 l O2/min or intubated) * Atrial Fibrillation with heart \>120 beats per minute * Inability to cooperate to or accept oral intake of food, including presence of major gastrointestinal discomfort. * If suspected or confirmed acute myocardial infarction as cause of acute heart failure, patients can be recruited 5 days after hospitalization in the absence of malignant arrhythmias (e.g. ventricular tachycardia) or clinically significant residual angina pectoris.