The Effect of Continuous Intravenous Magnesium Sulfate Infusion on the Incidence of Atrial Fibrillation After Cardiac Surgery: a Prospective Randomized Controlled Clinical Trial

INTERVENTION: Placebo group:Continuous intravenous infusion of 0.9% normal saline;Magnesium Sulfate group:Continuous Intravenous Magnesium Sulfate Infusion; CONDITION: Postoperative Atrial Fibrillation (POAF) PRIMARY OUTCOME: Incidence of new‐onset postoperative atrial fibrillation (POAF) within the first 5 postoperative days; SECONDARY OUTCOME: Duration of postoperative atrial fibrillation;ICU and hospital length of stay;Serious adverse events (SAEs) such as postoperative hypotension and heart rate abnormalities; INCLUSION CRITERIA: 1. Patients aged 18–85 years scheduled for elective isolated coronary artery bypass grafting (CABG) under cardiopulmonary bypass; 2. Preoperative heart rate >=50 beats per minute (bpm), with sinus rhythm or correctable cardiac arrhythmias; 3. Provision of signed informed consent, with the ability to understand the study procedures and a willingness to participate voluntarily. 4. Preoperative serum magnesium levels within the normal range (0.75–1.05 mmol/L). 5. No contraindications to the planned surgical procedures or standard perioperative management.