What are the oral anticoagulant (OAC) recommendations for patients with May-Thurner syndrome, and is lifelong anticoagulation necessary?

Oral Anticoagulation Recommendations for May-Thurner Syndrome

For patients with May-Thurner syndrome who have experienced a deep vein thrombosis (DVT), lifelong anticoagulation is recommended following endovascular intervention with stent placement to prevent recurrent thrombotic events.

Understanding May-Thurner Syndrome

May-Thurner syndrome (MTS) is an anatomical variant where the left common iliac vein is compressed by the overlying right common iliac artery against the lumbar vertebrae, leading to venous outflow obstruction and increased risk of left-sided DVT.

Management Approach

Initial Treatment

1. Endovascular intervention is the primary treatment for MTS with DVT:

   • Catheter-directed thrombolysis/mechanical thrombectomy
   • Angioplasty and stent placement in the compressed iliac vein

2. Anticoagulation therapy must be initiated immediately:

   • Begin with parenteral anticoagulation (LMWH or UFH) during the acute phase
   • Transition to oral anticoagulation after endovascular intervention

Anticoagulation Duration

• Lifelong anticoagulation is recommended based on case reports showing high recurrence rates even after stent placement 1, 2, 3
• Multiple case studies demonstrate recurrent thrombosis despite stent placement when anticoagulation is discontinued 4, 5

Choice of Anticoagulant

1. Direct Oral Anticoagulants (DOACs):

   • Can be used effectively in MTS patients following stent placement 1
   • Rivaroxaban has been successfully used in case reports, though partial stent thrombosis has been observed in some cases requiring repeat intervention 1

2. Vitamin K Antagonists (Warfarin):

   • Traditionally used in MTS patients with target INR 2.0-3.0
   • Has been shown effective in multiple case reports with follow-up periods of 6-18 months 3, 4

Special Considerations

Monitoring and Follow-up

• Regular vascular imaging (duplex ultrasound) every 3-6 months in the first year, then annually
• Assess for:
  • Stent patency
  • Recurrent thrombosis
  • Post-thrombotic syndrome

Anticoagulation Management for Procedures

• For patients requiring temporary interruption of anticoagulation:
  • Hold DOACs 24-48 hours before low bleeding risk procedures 6
  • Hold DOACs 48-72 hours before high bleeding risk procedures 6
  • Resume anticoagulation 24 hours after low bleeding risk procedures 6
  • For high bleeding risk procedures, delay resumption for 48-72 hours 6

Renal Function Monitoring

• For patients on DOACs with creatinine clearance ≥50 mL/min: monitor renal function every 6-12 months 7
• For patients on DOACs with creatinine clearance <50 mL/min: monitor renal function approximately every 3 months 7

Pitfalls and Caveats

• Anticoagulation alone without stent placement is insufficient for MTS treatment and leads to high recurrence rates 3, 5
• Failure to diagnose MTS in patients with left-sided DVT (especially young women) can lead to inappropriate treatment and recurrent thrombosis 4
• Some patients may require combination therapy with antiplatelet agents and anticoagulants if they develop arterial thrombosis or have recurrent events despite standard therapy 2

Conclusion

The evidence strongly supports lifelong anticoagulation for patients with May-Thurner syndrome following endovascular intervention to prevent recurrent thrombotic events and post-thrombotic syndrome. While case reports have shown success with both warfarin and DOACs, the decision should prioritize the prevention of recurrent thrombosis, which poses significant morbidity risks.