This study is a multicenter, randomized controlled, double-blind, placebo-controlled parallel trial designed to evaluate the effect of perioperative supplementation with Compound Vitamin B on patients undergoing cardiovascular surgery. A total of 1,000 patients aged 18-80 years who are scheduled to receive cardiovascular surgeries such as coronary artery bypass grafting (CABG) and valve replacement will be enrolled. They will be randomly assigned at a 1:1 ratio to either the experimental group (perioperative supplementation with Compound Vitamin B tablets, once daily from 3 days before surgery to 6 months after surgery) or the control group (oral placebo), with both groups receiving standardized perioperative treatment.

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.