What is the management of endovenous heat-induced thrombosis?

Classification and Management of Endovenous Heat-Induced Thrombosis (EHIT)

For endovenous heat-induced thrombosis (EHIT), treatment should be tailored according to the EHIT classification, with aspirin recommended for class 1-2 EHIT and systemic anticoagulation required for class 3-4 EHIT to prevent progression to deep vein thrombosis or pulmonary embolism.

Classification of EHIT

The American Venous Forum (AVF) EHIT classification system combines the previously used Kabnick and Lawrence classification systems 1:

• Class I: Thrombus extends to saphenofemoral junction (SFJ) but does not enter the deep venous system
• Class II: Thrombus extends into the deep venous system with ≤50% occlusion
• Class III: Thrombus extends into the deep venous system with >50% occlusion
• Class IV: Complete occlusion of the deep venous system

Risk Factors for EHIT

Several factors increase the risk of developing EHIT:

• Larger vein diameter 2, 3
• Male sex 3
• Multiple concomitant phlebectomies 3
• Concomitant sclerotherapy 2
• Older age (median age 59 vs 56 years in patients without EHIT) 3

Management Algorithm Based on EHIT Classification

Class I EHIT

• Treatment: Observation and aspirin (81-325mg daily) 4, 3
• Follow-up: Duplex ultrasound in 1-2 weeks to assess progression 4
• Duration: Continue until resolution, typically 2-4 weeks 3

Class II EHIT

• Treatment: Aspirin (81-325mg daily) 4, 3
• Follow-up: Duplex ultrasound in 1-2 weeks 4
• Duration: Continue until resolution, typically 2-4 weeks 3
• Note: Consider anticoagulation in patients with history of DVT or other risk factors 3

Class III EHIT

• Treatment: Systemic anticoagulation 4, 1
  • Options include:
    • LMWH (preferred over unfractionated heparin) 5, 6
    • Direct oral anticoagulants (DOACs) 5, 6
    • Vitamin K antagonists (target INR 2.0-3.0) 5
• Follow-up: Duplex ultrasound in 1-2 weeks 4
• Duration: Minimum 3 months of anticoagulation 6

Class IV EHIT

• Treatment: Immediate systemic anticoagulation 4, 1
  • LMWH or unfractionated heparin initially, followed by oral anticoagulation 5, 6
• Follow-up: More frequent ultrasound monitoring (e.g., weekly until improvement) 4
• Duration: 3-6 months of anticoagulation 5, 6

Efficacy and Outcomes

• Systemic anticoagulation is highly effective in preventing progression of class 3-4 EHIT with a low risk of bleeding complications 4
• Aspirin treatment for class 1-2 EHIT has a low progression rate of approximately 3% 4
• Overall incidence of EHIT is approximately 1.5-3% of all endovenous ablation procedures 4, 3
• Pulmonary embolism is rare, occurring in only 0.03-0.11% of cases 3, 7

Special Considerations

• Most EHIT cases (87%) are asymptomatic and detected on routine post-procedure ultrasound 4
• Symptomatic patients may present with pain (10%) or swelling (2.9%) 4
• Routine duplex ultrasound should be performed within 1-2 weeks after endovenous ablation to detect EHIT 4, 2
• Consider earlier ultrasound in patients with multiple risk factors or symptoms suggestive of venous thromboembolism 2
• EHIT resolution typically occurs within 2-4 weeks in most patients 3

Preventive Measures

• Consider prophylactic aspirin in high-risk patients (large vein diameter, multiple phlebectomies) 3
• Maintain adequate distance from the saphenofemoral junction during ablation 1
• Consider limiting the extent of concomitant procedures in high-risk patients 2, 3

Pitfalls to Avoid

• Failure to perform routine post-procedure ultrasound surveillance
• Undertreatment of class 3-4 EHIT (requires systemic anticoagulation)
• Overtreatment of class 1-2 EHIT (typically requires only aspirin)
• Inadequate follow-up imaging to ensure resolution
• Neglecting to identify and address risk factors in high-risk patients

The management of EHIT should focus on preventing progression to clinically significant deep vein thrombosis or pulmonary embolism while avoiding unnecessary anticoagulation in low-risk cases.