Cardiac Surgery, The Role of Protein


Clinical RCTs (2020–2025) with Positive Evidence for Protein Supplementation After Cardiac Surgery


Between 2020 and 2025, several clinical RCTs have provided positive evidence that protein supplementation after cardiac surgery leads to improved patient outcomes. These studies show that both oral and intravenous protein or amino acid supplementation can reduce complications (such as acute kidney injury), enhance physical recovery, and improve quality of life in patients undergoing cardiac surgery. The interventions were safe, with no significant increase in adverse events.

Detailed Study Highlights

1. PROTECT-CS Study (2021–2025)

  • Design: Double-blind, placebo-controlled RCT, n=150 (pre)frail adults ≥60 years.
  • Intervention: Leucine-rich protein supplement (25g protein + 3g leucine), twice daily, perioperatively.
  • Outcomes: Significant improvements in physical function (SPPB, SF-36), HRQoL, and frailty reduction; enhanced recovery and mood; no increase in adverse events.
  • Clinical Significance: Demonstrates that targeted protein supplementation can meaningfully improve recovery and quality of life in older, frail cardiac surgery patients .

2. HMB/Arginine/Glutamine Supplementation Trials (2022–2025)

  • Design: Double-blind, placebo-controlled RCTs in elderly open heart surgery patients.
  • Intervention: Oral supplement (HMB, glutamine, arginine), 1–2x/day for 14–28 days pre-op.
  • Outcomes: Improved 6-min walk test, reduced complications, better nutritional and psychological status, shorter hospital stay.
  • Clinical Significance: Suggests that perioperative amino acid supplementation can enhance physical recovery and reduce complications in elderly cardiac surgery patients.

3. Intravenous Amino Acids for Kidney Protection (2024)

  • Design: Multinational, double-blind RCT in adults undergoing cardiac surgery with cardiopulmonary bypass.
  • Intervention: IV balanced amino acids (2g/kg/day) for up to 3 days post-op.
  • Outcomes: Significant reduction in AKI incidence (e.g., AKI incidence 30.3% in AA group vs. 56.2% in control; HR: 0.44, p=0.04), increased urine output, no increase in adverse events.
  • Clinical Significance: IV amino acid supplementation is effective in reducing the risk of acute kidney injury after cardiac surgery, especially when administered intraoperatively.

Key Patterns and Recommendations

  • Route & Timing: Both oral and intravenous protein supplementation are effective; intraoperative IV administration may offer the greatest renal protection.

  • Target Population: Benefits are most pronounced in elderly, frail, or malnourished patients.

  • Safety: No significant increase in adverse events reported across studies.

  • Clinical Impact: Improved physical function, reduced complications (especially AKI), better nutritional and psychological status, and shorter hospital stays.

Conclusion

Summary Box:
Recent RCTs (2020–2025) provide robust evidence that perioperative protein supplementation—whether as oral leucine-rich shakes, amino acid blends, or intravenous amino acids—improves clinical outcomes in cardiac surgery patients. These interventions are safe and particularly beneficial for elderly, frail, or malnourished individuals, supporting their integration into standard perioperative care protocols.