Before la surgery:

Transthoracic cardiac echography will be done systematically, to measure among other things the size of the left atrium.

During surgery:

Surgery under extracorporeal circulation: tissue samples will be harvested from the right atrium (one before clamping of the aorta (T0= pre-ischemia sample), immediately before declamping of the aorta (T1= post-ischemia sample).

Surgery without extracorporeal circulation: tissue samples from the right atrium before CABG (T0) and a second sample after CABG (T1).

In parallel with the harvesting of cardiac tissue, blood samples will be taken at different times (H0, H3, H24) to correlate tissue data with systemic data. These will be taken by the anesthetists.

After the surgery:

Holter ECG will be set up for 7 days of continuous recording. Each patient will fill in an observation notebook. The biological samples will be analysed immediately and the biological data obtained will be recorded in the observation notebook.

Inclusion Criteria:

• Patients who have provided written informed consent
• Patients covered by the national health insurance scheme
• Heart surgery (CABG) with and without extracorporeal circulation
• Elective or deferred emergency surgery
• Consecutive patients aged less than 80 years

Exclusion Criteria:

• Patients less than 18, under guardianship
• Patients over 18, under guardianship
• Patients who do not understand the study data
• Patients undergoing emergency surgery who therefore cannot be given or understand the explanations for the study (patients in shock, intubated patients with mechanical ventilation)
• History of heart surgery
• History of AF
• Treatment with Cordarone.

Coronary artery bypass graft with or without extracorporeal circulation