Does thalassemia increase the risk of Venous Thromboembolism (VTE)?

Thalassemia and Venous Thromboembolism Risk

Yes, thalassemia significantly increases the risk of venous thromboembolism (VTE), particularly in patients with thalassemia intermedia who are splenectomized. 1, 2

Risk Stratification in Thalassemia

The risk of VTE varies significantly between different types of thalassemia:

• Thalassemia Intermedia: Highest risk group

  • 4% overall prevalence of thrombotic events 2
  • Up to 29% in transfusion-independent patients 1
  • Risk is particularly elevated in splenectomized patients

• Thalassemia Major: Lower risk group

  • 0.9% overall prevalence of thrombotic events 2
  • Only 2% in regularly transfused patients 1

Pathophysiological Mechanisms

Several factors contribute to the hypercoagulable state in thalassemia:

1. Abnormal red blood cells: Damaged RBCs with procoagulant activity circulate in higher numbers in transfusion-independent patients 1

2. Splenectomy: Major risk factor that leads to:

   • Thrombocytosis
   • Increased circulation of abnormal RBCs 3
   • 4.38 times higher risk of thromboembolism compared to non-splenectomized patients 2

3. Inadequate transfusion: Patients receiving less than 154 mL/kg/year of RBC transfusions show higher hypercoagulable risk 4

4. Other factors:

   • Female gender 2
   • Profound anemia (hemoglobin <9 g/dL) 2
   • Platelet activation and endothelial cell activation 3

Clinical Implications and Management

Risk Assessment

• TEG (Thromboelastography) may be useful for identifying high-risk patients 4
• 58.82% of transfusion-dependent thalassemia patients show hypercoagulable state on TEG 4

Prevention Strategies

1. Regular transfusion therapy:

   • Reduces proportion of abnormal RBCs
   • Suppresses erythropoiesis
   • Lowers levels of circulating coagulation markers
   • Reduces elevated pulmonary artery pressure 3

2. Antiplatelet therapy:

   • Aspirin is recommended for splenectomized patients with thrombocytosis 3

3. Reassessment of splenectomy indications:

   • Given the increased risk of thromboembolic events, the rationale for splenectomy should be carefully evaluated 2

Clinical Pearls and Pitfalls

• Pattern of thrombosis: Venous events occur more frequently in thalassemia intermedia, while arterial events are more common in thalassemia major 2

• Monitoring: Regular screening for hypercoagulability should be considered in high-risk patients, especially those who are splenectomized or inadequately transfused

• Transfusion strategy: Maintaining adequate transfusion regimens (>154 mL/kg/year) may help reduce hypercoagulable risk 4

• Vigilance: Despite being relatively rare overall (1.65% of all thalassemia patients), thromboembolic events represent a potentially fatal complication that requires attention 2

The evidence clearly demonstrates that thalassemia, particularly thalassemia intermedia in splenectomized patients, significantly increases the risk of VTE. Clinicians should be vigilant about this risk and consider appropriate preventive measures in high-risk patients.