Post operative atrial fibrillation (POAF) is one of the most common complications that takes place worldwide after coronary artery bypass surgeries (CABG). Many studies suggest using vitamin C as an additional treatment alongside standard therapies, such as statins and β-blockers, to reduce the risk of postoperative atrial fibrillation (POAF) in patients undergoing (CABG). Supplemental therapy with vitamin C may provide a more robust preventive effect against POAF compared to using statins and β-blockers due to its strong antioxidant effect. This implies that vitamin C can enhance the effectiveness of those medications used for POAF prevention by decreasing oxidative stress induced by the surgery.

There are conflicting data on whether or not vitamin C as an antioxidant has a protective effect against postoperative atrial fibrillation and has a significant role in shortening length of ICU and hospital stay . Even in those studies that show positive relationship of vitamin C in AF prevention, there is a diversity in the dosing regimen of vitamin C used among those previous studies.

To the best of our knowledge, most researches were conducted predominantly within a single geographic region, such as Iran, this raises the concerns about the potential bias and limits our ability to apply the findings to a broader global population.

Here, the investigators aimed to evaluate the effectiveness of vitamin C supplementation and to figure out which dose of vitamin C will prevent post-operative AF and decrease complications such as hospital stay, pneumonia and surgical site infection among older Egyptian adults.

Inclusion criteria:

• Patients who underwent elective isolated on-pump coronary artery bypass surgery
• Age: 50 to 70 years
• No history of Coronary artery by pass surgery
• Taking maximum tolerated beta-blocker before and after surgery
• Normal left atrium and left ventricle dimensions

Exclusion Criteria:

• preoperative history of Atrial fibrilliation
• permanent pacemaker or significant bradycardia
• Hyperoxaluria or history of nephrolithiasis
• Left ventricular ejection fraction < 40%
• Contraindications to beta-blocker or vitamin C.
• Patients with history of vitamin C consumption before surgery.
• Chronic kidney disease with creatinine >2 mg/dl.

The study was double blinded were Participant (patients), Care Provider (nurses, cardiac surgeons, and ICU physicians) were blinded but the outcome assessors (clinical pharmacist) who collect data were not blinded