What is the recommended anticoagulation regimen for a patient with May-Thurner syndrome and a history of Deep Vein Thrombosis (DVT) who has undergone venous stenting?

Anticoagulation Regimen for May-Thurner Syndrome with DVT Post-Stenting

Patients with May-Thurner syndrome who have undergone venous stenting for DVT should receive therapeutic anticoagulation with a direct oral anticoagulant (DOAC) such as apixaban, rivaroxaban, edoxaban, or dabigatran for a minimum of 3 months, followed by indefinite anticoagulation due to the persistent anatomic compression risk factor. 1

Initial Treatment Phase (First 3 Months)

DOAC therapy is strongly preferred over warfarin for the initial treatment phase. 2, 1 The recommended options include:

• Apixaban: 10 mg twice daily for 7 days, then 5 mg twice daily 3
• Rivaroxaban: 15 mg twice daily with food for 21 days, then 20 mg once daily with food 4
• Edoxaban or dabigatran at standard treatment doses 2, 1

The superiority of DOACs over warfarin is based on moderate-certainty evidence demonstrating better efficacy and safety profiles in acute VTE treatment. 2

If warfarin must be used (patient preference or contraindication to DOACs), maintain a target INR of 2.5 with a therapeutic range of 2.0-3.0, preceded by parenteral anticoagulation (LMWH, fondaparinux, or UFH) for at least 5 days and until INR ≥2.0 for 24 hours. 2, 1

Extended Anticoagulation (Beyond 3 Months)

Indefinite anticoagulation is recommended for May-Thurner syndrome even after successful stenting. 1 This recommendation is based on the understanding that May-Thurner represents a chronic, persistent anatomic risk factor rather than a transient provocation. 2

The rationale for extended therapy includes:

• Recurrent VTE occurs more frequently with anticoagulation alone compared to those receiving continued anticoagulation after stenting 2
• Primary stent patency with anticoagulation approaches 60-100% at one year, highlighting the protective role of continued anticoagulation 1
• The anatomic compression persists despite stenting, warranting ongoing thromboprophylaxis 1

Dosing Options for Extended Phase

Two acceptable approaches exist for extended anticoagulation beyond 3 months:

Standard-dose DOAC (preferred for most patients):

• Continue the same therapeutic dose used in the initial treatment phase 1
• Provides maximum protection against recurrent thrombosis

Reduced-dose DOAC (for patients with higher bleeding risk):

• Rivaroxaban 10 mg once daily with or without food 1, 4
• Apixaban 2.5 mg twice daily 1, 3

The choice between standard and reduced dosing should be based on bleeding risk assessment, with standard dosing preferred unless bleeding concerns are significant. 1

Critical Considerations and Pitfalls

Anticoagulation alone without stenting is insufficient for May-Thurner syndrome. The mechanical compression must be addressed via stenting, as anticoagulation alone leads to higher recurrence rates. 2, 1 However, this question assumes stenting has already been performed.

Reassess the benefit-risk ratio periodically (e.g., annually) for patients on extended anticoagulation, evaluating for changes in bleeding risk, patient preference, and stent patency. 2

Monitor for stent thrombosis, which can occur even with appropriate anticoagulation. Case reports document partial stent thrombosis occurring 5-12 months post-procedure despite therapeutic anticoagulation. 5, 6

Special Populations

For patients with active cancer and May-Thurner syndrome:

• Oral factor Xa inhibitors (apixaban, edoxaban, rivaroxaban) are preferred over LMWH 2, 1
• Extended anticoagulation with no scheduled stop date is recommended 2, 1

For patients unable to tolerate DOACs:

• LMWH is an acceptable alternative for both initial and extended therapy 2
• Warfarin with INR 2.0-3.0 remains an option, though less preferred 2, 1

Evidence Quality and Consensus

The recommendation for indefinite anticoagulation after stenting represents expert consensus rather than high-quality randomized trial evidence. 2 No prospective randomized controlled trials have rigorously tested anticoagulation duration after stenting for May-Thurner syndrome. 2 However, the consistent observation of higher recurrence rates with limited anticoagulation, combined with the persistent anatomic abnormality, supports indefinite therapy. 2, 1

The general consensus among vascular specialists is to treat iliac vein obstructive lesions with stents plus indefinite anticoagulation, as recurrent VTE in the affected limb occurs more frequently with time-limited anticoagulation. 2