This proof of concept study aims to evaluate the effects of applying ketone bodies to human atrial tissue biopsies using an atrial strips model and high resolution respirometry.

Ketone bodies are high energy molecules which are naturally occurring in the body during fasting or stress.

Recently, ketone bodies have been shown to improve cardiac function in patients with heart failure(1) through a mechanism, which has yet to be elaborated.

We wish to evaluate the effects of ketone body administration on cardiac tissue subjected to ischemia reperfusion injury. We will evaluate contractile force of the and the mitochondrial performance. Cardiac atrial tissue will be obtained from patients undergoing coronary artery bypass grafting (CABG) or valve replacement surgery. Patients will be recruited after signing an informed consent and allocated in heart failure / non-heart failure groups based on a clinical evaluation.

Inclusion Criteria:

• EF < / > 45%, hospitalized for elective CABG or heart valve surgery

Exclusion Criteria:

• Myocardial infarction within 4 weeks, atrial fibrillation, medically treated thyroid disease, oral treatment with opioids.