What are the guidelines for using tranexamic acid (TXA) in off-pump and on-pump Coronary Artery Bypass Grafting (CABG)?

Guidelines for Tranexamic Acid Use in Off-Pump and On-Pump CABG

Lysine analogues such as tranexamic acid (TXA) are strongly recommended for both on-pump and off-pump CABG procedures to reduce perioperative blood loss and transfusion requirements. 1

Evidence-Based Recommendations

On-Pump CABG

• Class I, Level of Evidence A: Tranexamic acid or epsilon aminocaproic acid is recommended during on-pump cardiac surgical procedures 1
• TXA significantly reduces:
  • Perioperative blood loss
  • Allogeneic blood transfusion requirements
  • Risk of reoperation due to bleeding 2

Off-Pump CABG

• Class IIa, Level of Evidence A: It is reasonable to consider off-pump CABG to reduce perioperative bleeding and allogeneic blood transfusion 1
• When TXA is used in off-pump CABG:
  • Significantly reduces overall risk of allogeneic blood component transfusion (risk ratio = 0.47) 3
  • Reduces packed red blood cell transfusions (risk ratio = 0.51) 3

Dosing Recommendations

Standard Dosing Protocol

• Maximum recommended total dose: 100 mg/kg to minimize risk of seizures 1

Dosing Options

1. High-dose protocol:

   • Loading dose: 30 mg/kg after anesthesia induction
   • Maintenance: 15 mg/kg/h until end of surgery
   • CPB circuit priming dose: 2 mg/kg 4, 5

2. Low-dose protocol:

   • Loading dose: 15 mg/kg after anesthesia induction
   • Maintenance: 6 mg/kg/h until end of surgery
   • CPB circuit priming dose: 1 mg/kg 4

Research indicates that low-dose protocols are as effective as high-dose protocols for antifibrinolysis in primary CABG with CPB, with comparable chest tube output, perioperative blood product transfusion, and incidence of reoperation for bleeding 4.

Safety Considerations

• Higher doses of TXA (>100 mg/kg total) appear to be associated with increased risk of seizures 1
• Current evidence shows no significant association between TXA use and adverse events such as:
  • Myocardial infarction
  • Stroke
  • Pulmonary embolism 3

However, it's important to note that most studies have insufficient sample sizes to detect rare but clinically significant adverse events 3.

Implementation in Practice

• TXA should be administered as part of a multimodal approach to blood conservation
• Class I, Level of Evidence A: A multimodal approach with transfusion algorithms, point-of-care testing, and a focused blood conservation strategy should be used to limit the number of transfusions 1
• For patients on antiplatelet therapy:
  • Clopidogrel and ticagrelor should be withheld for at least 5 days before elective CABG
  • Prasugrel should be withheld for at least 7 days before elective CABG 1

Special Considerations

• Topical application of TXA (1g diluted in 100ml normal saline) in the mediastinal cavity before chest closure has not been shown to reduce postoperative bleeding in on-pump CABG and is not recommended 6
• For patients continuing dual antiplatelet therapy up to surgery, TXA has demonstrated particular efficacy in reducing blood loss, major bleeding, reoperation, and allogeneic transfusion 2

TXA administration should be incorporated into standardized protocols for both on-pump and off-pump CABG procedures as part of comprehensive blood conservation strategies to improve patient outcomes by reducing bleeding complications and transfusion requirements.