This study aims to assess the percent and risk factors of postoperative atrial fibrillation in patients undergoing cardiac surgery in Assiut university heart hospital
≥18 years scheduled for first-time planned cardiac surgery ( CABG and Valve replacement)
Patients who are in sinus rhythm and not taking any antiarrhythmic medication, other than beta-adrenergic blocking agents, at the time of surgery.
Willingness to participate and provision of informed consent
Prior history of cardiac surgery.
Pediatric population less than 18 years.
Patients with history of hyperthyroidism
Patients with electrolyte disturbance