Vitamin B Supplementation for Patients Undergoing Cardiovascular Surgery

Inclusion Criteria: * Aged 18-80 years, regardless of gender; * Scheduled to receive cardiovascular surgery at the research center, including coronary artery bypass grafting (CABG), cardiac valve replacement/repair, and great vessel surgery; * Preoperative assessment indicates that the patient is expected to complete the 6-month postoperative follow-up; * The patient or their authorized agent signs a written informed consent form. Exclusion Criteria: * Regular supplementation with Compound Vitamin B (daily dose ≥ 1.5 times the recommended dietary allowance) or separate supplementation with folic acid, vitamin B6, or B12 within 3 months before surgery; * Severe hepatic or renal insufficiency (liver function: ALT/AST \> 3 times the upper limit of normal, or total bilirubin \> 2 times the upper limit of normal; renal function: serum creatinine \> 265 μmol/L, or requiring long-term dialysis treatment); * Malignant tumors, severe hematological diseases (e.g., megaloblastic anemia, aplastic anemia), severe malnutrition (albumin \< 25 g/L); * History of allergy to Compound Vitamin B preparations or placebo components; Pregnant women, lactating women, or those planning to become pregnant during the study period; * Currently participating in other interventional clinical trials; * Moderate to severe cognitive impairment without a fixed caregiver, unable to cooperate with treatment and follow-up; * Preoperatively diagnosed with severe infection, septicemia, or septic shock.