Detailed study characteristics, risk-of-bias tables, subgroup results

From 152 records screened, 19 studies were included: three cohort studies (170 patients) and 16 case reports/small series.Cohort studies:Standardized bivalirudin protocols (bolus 1.0–1.2 mg/kg, infusion 2.0–2.7 mg/kg/h, ACT ≈480 s) were effective.Major bleeding: pooled incidence 10.6% (95% CI: 6.4–16.9%).Thromboembolic events: pooled incidence 2.1% (95% CI: 0.4–4.8%).Early mortality: ≤3%.No CPB circuit thrombosis or oxygenator exchanges were required.Around 14% of patients needed dose adjustments due to ACT variability.Case reports/series:Showed feasibility in high-risk settings (emergent surgery, transplantation, pediatrics, renal failure, redo sternotomy).ACT-guided protocols maintained circuit integrity, with no perioperative deaths or circuit failures.Some cases required modified monitoring (e.g., plasma-modified ACT in thrombocytopenia, dose reduction in pediatrics).Secondary outcomes:Reoperation for bleeding: 5.3%.Transfusion needs were variable but not excessive.ICU stay: 2–4 days; hospital stay: 7–10 days.No ECMO or mechanical circulatory support was required.