What is the recommended anticoagulation regimen for cardiac bridging?

Cardiac Bridging Anticoagulation Regimen

For patients requiring temporary interruption of oral anticoagulation therapy, bridging anticoagulation should be individualized based on thromboembolic risk, with therapeutic-dose LMWH recommended for high-risk patients with mechanical heart valves, particularly those with mitral valve replacements or additional risk factors. 1

Risk Stratification for Bridging Therapy

High Thromboembolic Risk (Bridging Recommended)

• Mechanical mitral valve replacement
• Older-generation mechanical valves (ball-cage or tilting disc)
• Recent thromboembolic event (within 3 months)
• Multiple mechanical valves
• Mechanical valve plus additional risk factors:
  • Atrial fibrillation
  • Previous thromboembolism
  • Hypercoagulable condition
  • Left ventricular dysfunction (EF <35%)

Lower Thromboembolic Risk (Bridging May Be Considered)

• Bileaflet aortic valve prosthesis without additional risk factors

Standard Bridging Protocol

Preoperative Management

1. Stop oral VKA (warfarin) 3-4 days before procedure
2. Begin bridging anticoagulation when INR falls below therapeutic threshold (2.0-2.5):
   • Usually 36-48 hours before surgery
   • For high-risk patients: Therapeutic-dose LMWH (1 mg/kg twice daily)
   • For moderate/low-risk patients: Prophylactic-dose LMWH (40 mg daily)
3. Last preoperative dose timing:
   • LMWH: Administer last dose approximately 24 hours before surgery rather than 12 hours before 1
   • IV UFH: Stop infusion 4-6 hours before procedure 1

Postoperative Management

1. Resume anticoagulation based on bleeding risk:
   • Low bleeding risk: Resume therapeutic-dose anticoagulation 24 hours after procedure
   • High bleeding risk: Consider delayed resumption or reduced-dose regimen initially
2. Restart oral VKA 12-24 hours postoperatively once hemostasis is achieved 1
3. Continue bridging until INR returns to therapeutic range

Choice of Bridging Agent

Unfractionated Heparin (UFH)

• Preferred for:
  • Patients with severe renal impairment (CrCl <30 ml/min)
  • Patients on dialysis
  • Situations requiring rapid reversal
• Dosing: IV infusion to achieve aPTT 1.5-2.0 times control 1
• Alternative: SC regimen (250 International Units/kg twice daily) 1

Low-Molecular-Weight Heparin (LMWH)

• Standard dosing for high-risk patients:
  • Enoxaparin 1 mg/kg twice daily 1
  • Dose reduction for renal impairment
• Monitoring: Consider anti-Xa monitoring for high-risk patients

Special Considerations

Mechanical Heart Valve Patients

• Evidence for bridging in mechanical valve patients is based primarily on observational studies rather than RCTs 1
• Recent data suggest bridging may increase bleeding risk without significantly reducing thromboembolism 1
• Despite this, bridging remains recommended for high-risk mechanical valve patients, particularly those with mitral valve replacements 1, 2

Emergency Procedures

• For emergency surgery in patients on VKA therapy, consider:
  • Fresh frozen plasma
  • Prothrombin complex concentrate 1

Potential Pitfalls

1. Bleeding complications: Bridging therapy increases bleeding risk compared to no bridging
2. Inadequate anticoagulation: Subtherapeutic dosing may increase thrombotic risk in high-risk patients
3. Renal impairment: Failure to adjust LMWH dosing can lead to accumulation and bleeding
4. Delayed resumption: Extended periods without anticoagulation increase thrombotic risk

Monitoring

• Monitor INR regularly during bridging period
• For patients on LMWH, consider anti-Xa monitoring in high-risk cases
• Vigilant assessment for signs of bleeding or thromboembolism

The decision to bridge should carefully weigh thrombotic risk against bleeding risk, with the understanding that recent evidence suggests bridging may increase bleeding complications without significantly reducing thromboembolism in many patients 1.