This is a non-randomized interventional prospective study, aiming to provide insight into cardiac substrate utilization in the fed state. Patients will participate during an elective PVI procedure which would have taken place regardless of the current study. During this study, study subjects will receive peripheral parenteral nutrition (PPN) through an intravenous (iv) line. During the procedure, blood samples will be drawn from the catheters which will be in situ for the purpose of the elective PVI procedure. Cardiac arteriovenous (A-V) gradients of metabolites will be measured, reflecting cardiac uptake and release of metabolites in the fed state.

The heart requires tremendous amounts of energy to sustain its continuous mechanical work. The heart can utilize various metabolic substrates to generate energy, including carbohydrates, lipids, amino acids and ketone bodies. However, most research on cardiac fuel use has been done in rodents and surprisingly little is known about cardiac fuel use in patients with heart disease. Prior experimental studies showed that carbohydrates are important fuels for cardiac energy production. In contrast, a recent study in patients with heart disease showed that the heart only utilizes little amounts of carbohydrates. This study was however, performed in fasting subjects, which could have an important effect on substrate preference. The primary aim of this non-randomized interventional prospective study is to provide insight into cardiac substrate utilization in the fed state. Patients will participate during an elective PVI procedure which would have taken place regardless of the current study. During this study they will receive peripheral parenteral nutrition (PPN) through an intravenous (iv) line. Blood samples will be drawn with the catheters which will already be in situ for the purpose of the elective PVI procedure. Cardiac arteriovenous (A-V) gradients of metabolites will be measured, reflecting cardiac uptake and release of metabolites in the fed state.

Inclusion Criteria:

• Undergoing elective PVI procedure
• Adult age (≥ 18 years)
• Have given verbal and written informed consent

Exclusion Criteria:

• Chronic renal disease with an estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m2
• Chronic liver disease and/or severe liver dysfunction with ASAT and/or ALAT > 3x the upper limit of normal (ULN)
• Pregnancy or breastfeeding
• Insulin dependent diabetics
• Congenital metabolic disease
• Weight below 40 kg
• Inability to understand and read Dutch or English
• Known allergy or hypersensitivity to any of the non-investigational products in the study protocol
• Any other clinical condition that would jeopardize patient's safety while participating in this trial or may prevent the patient from adhering to the trial protocol.