Among patients undergoing heart surgery, a measurable degree of heart muscle tissue injury is expected. The level of injury can be shown by measuring the blood levels of specific molecules called cardiac biomarkers. Those cardiac biomarkers are often used in the acute cardiac care to diagnose a myocardial infarction.

Postoperative heart infarction remains a frequent and important complication after heart surgery.Therefore it is important to recognize any cardiac event in patients who underwent heart surgery. Although different diagnostic tools can be used to recognize these events, few is known about the value of those cardiac biomarkers to diagnose a myocardial infarction after heart surgery.

In this study the investigators will describe the concentration changes of those cardiac biomarkers over time in patients undergoing heart surgery, and the investigators will try to establish a upper level value who could indicate heart infarction.

This is a prospective interventional mono centre study. High-sensitivity troponin and CK-MB will be measured at different point of times in all adult patients undergoing cardiac surgery.

Experiments are conducted at the O.L.V. Hospital, Aalst, Belgium, in a fully equipped operating room and intensive care facility and in the presence of board-certified anesthesiologists for safety reasons. After approval by the institutional ethics committee and written informed consent, all adult patients scheduled for different types of cardiac surgery between June 2013 and June 2014 will be enrolled. Collected data include demographic information, presence of co-morbid conditions and basic preoperative laboratory testing (including Hs-cTn and CK-MB) (Table 1) as well as per- and postoperative factors (Table 2).

Four different surgeons will perform the surgeries. The revascularization strategy and work method are chosen according to each surgeon's preference and good clinical practice. Standard monitoring is used in all patients. Anaesthesia management is at the discretion of the attending anaesthesiologist and according to good clinical practice.

Serum levels of CK-MB and Hs-cTn will be measured at induction of anaesthesia (after placement of the arterial line), upon arrival at the intensive care unit (ICU), as well as every 3 hours for 12 hours, then every 6 hours the following 12 hours and a last sample is taken 48 hours after surgery. Samples are analysed at the department of Clinical Biochemistry of our institution with the Elecsys Troponin T hs immuno-assay. Lower limit of quantification being 0,14 Nano gram/L (company data).

Twelve-lead ECGs obtained routinely the day prior to surgery, immediately upon arrival at the ICU, and then 24 and 48 hours post-surgery will be retrospectively reviewed by a cardiologist blinded to all other data for evidence of new postoperative MI.

All cardiac events, as described by the Third Global MI Task Force definition of MI, will be noted. Additional ECG or transesophageal echocardiography will be done at the discretion of the attending ICU physician, according to ICU protocols and good clinical practice.

Approved automated record keeping system (MetaVision Suite, iMDSoft, the Netherlands) will be used in the ICU. The principal investigator and/or co-investigators will supervise data handling.

Inclusion Criteria:

• Each participant must be older than 18 years
• Undergoing cardiac surgery
• Each participant must have the mental capacity to decide whether he takes part in the trial or not.
• Each participant must voluntarily give his written informed consent.

Exclusion Criteria:

• Patients with severe or end-stage renal insufficiency.
• Insertion of assist devices.
• Surgery on urgent basis, that is, the same day after their coronary angiogram.