Background
Phase 3, multicenter, international, noninferiority RCT (TRICS-III). 5,243 high-risk patients (EuroSCORE ≥6) undergoing cardiac surgery with cardiopulmonary bypass (CPB) at 73 centers in 19 countries. Largest randomized transfusion trial in cardiac surgery. Enrolled patients at high perioperative risk of death, MI, or stroke.
Interventions and follow up
Arm A: Restrictive transfusion strategy — RBC transfusion threshold Hgb <7.5 g/dL (intraoperative/ICU) and <8.0 g/dL (post-ICU/ward)
Arm B: Liberal transfusion strategy — RBC transfusion threshold Hgb <9.5 g/dL (intraoperative/ICU) and <8.5 g/dL (post-ICU/ward)
Primary endpoint: Composite of death from any cause, MI, stroke, or new-onset renal failure requiring dialysis at 28 days (noninferiority design, margin OR 1.20)
mFollow up: 6 month
Arm B: Liberal transfusion strategy — RBC transfusion threshold Hgb <9.5 g/dL (intraoperative/ICU) and <8.5 g/dL (post-ICU/ward)
Primary endpoint: Composite of death from any cause, MI, stroke, or new-onset renal failure requiring dialysis at 28 days (noninferiority design, margin OR 1.20)
mFollow up: 6 month
Results
Composite primary endpoint: 11.4% vs 12.5%, OR 0.90 (95% CI 0.76–1.07) — noninferiority confirmed (P<.001)
6-month composite: 17.4% vs 17.1% — similar
RBC units transfused: 1.7 vs 2.8 units per patient — 39% reduction with restrictive
Patients receiving any transfusion: 52.3% vs 72.6%
6-month composite: 17.4% vs 17.1% — similar
RBC units transfused: 1.7 vs 2.8 units per patient — 39% reduction with restrictive
Patients receiving any transfusion: 52.3% vs 72.6%
Adverse events
Main adverse events: Surgical re-exploration, AF, pneumonia, AKI not requiring dialysis — all similar between groups. No significant difference in any individual component of the primary composite. Length of ICU stay and hospital stay similar.
Conclusions
A restrictive RBC transfusion strategy was noninferior to a liberal strategy in high-risk cardiac surgery patients, confirming that Hgb <7.5 g/dL is a safe transfusion trigger even in patients with cardiovascular disease undergoing major cardiac surgery.
Key Limitations
Key Limitations: Noninferiority design — cannot exclude small harms with restrictive strategy. Open-label (blinding impossible). Adherence imperfect in both arms. Hgb thresholds differed slightly between intraoperative and post-ICU phases, creating a complex protocol. The liberal arm threshold (9.5 g/dL) may not reflect current clinical practice, making the comparison slightly artificial. Excluded emergency surgery.
Clinical Context
TRICS-III confirmed that the restrictive threshold validated in TRICC (medical ICU) is safe in high-risk cardiac surgery, challenging older practice of liberal transfusion post-bypass. STS/SCA/EACTS guidelines now support restrictive thresholds (Hgb 7–8 g/dL) in stable cardiac surgery patients. This trial, combined with TRICC and TRISS, established Hgb 7–8 g/dL as the universal threshold across most surgical and critical care contexts.
References