The objective of this single-center pilot study is, with the help of a connected watch, to show the absence of recurrence or maintenance of sinus rhythm in patients with a Post Operative Atrial Fibrillation (POAF) and to help treating cardiologists in the care of these patients.

Inclusion Criteria:

• Major with an indication for conventional cardiac surgery with de novo postoperative AF onset.
• Agreeing to participate in the study and having signed an informed consent.
• Agreeing to undergo 12 months of postoperative monitoring.

Exclusion Criteria:

• Patient with pre-operative AF
• Patient who does not have a smartphone compatible with the connected watch.
• Patient unable to perform an ECG measurement independently.
• Patient with a physical constraint to the measurement (arteriovenous fistula...)
• Minors
• Pregnant or breast-feeding women
• Adults under guardianship, under curatorship
• Patients whose life expectancy is less than 1 year
• Patients participating in another therapeutic trial likely to impact the evaluation criteria of the MONHYCARD study
• Contraindication to long-term anticoagulants
• Patients implanted with a mechanical valve prosthesis pre-operatively or after surgery

Patients with postoperative atrial fibrillation meeting the study eligibility criteria