Splanchnic vein thrombosis: Impact on survival outcomes in younger patients with PV or ET

Splanchnic vein thrombosis (SVT) occurs in approximately 5% of patients with myeloproliferative neoplasms (MPN) and development is commonly associated with the Janus kinase 2^V617F driver mutation either at diagnosis or follow-up.¹

Here, we summarize a study published by Garrote et al.¹ in Annals of Hematology on the role of SVT and genomic characteristics in the outcomes and survival of patients with polycythemia vera and essential thrombocythemia.

Patient population¹

• A cohort of 255 patients aged 37–60 years were included:
  • 90 patients with SVT, with 59 of those presenting at MPN diagnosis, 10 before diagnosis, and 21 during follow-up.
  • 165 patients with MPN but without SVT as a control group
• Localization of SVT:
  • Splenoportal area, 64%
  • Hepatic vein (Budd-Chiari syndrome), 32%
  • Both locations, 3%
• The incidence of heterozygous Janus kinase 2 mutation was more common in patients with SVT compared with the control group (87% vs 69%, respectively; p < 0.05).

Key findings¹

• Compared with the control cohort, patients with SVT presented with a higher risk of:
  • Venous rethrombosis; hazard ratio (HR) 3.0 (95% confidence interval [CI], 1.5–6.0; p = 0.003) and after correction by age; HR 1.1, (95% CI, 1.08–1.15; p < 0.001)
  • Total thrombosis; HR 3.2, (95% CI, 1.6–6.4; p = 0.001) and after correction by age; HR 1.03 (95% CI, 0.99–1.06; p = 0.07)
  • Thrombosis at 10 years was 27% and 8%, respectively (p = 0.001).
• Patients with SVT also presented with:
  • lower rates of event-free survival; HR 3.0 (95% CI, 1.9–4.8; p < 0.001); and
  • association between molecular high-risk status and an increased risk of venous rethrombosis; HR 5.8 (95% CI, 1.4–24.0, p = 0.01).

• Patients who developed SVT during the follow-up period were more likely to be molecular high-risk than those with SVT present at diagnosis (52% vs 13%, respectively; p < 0.05).
• Median overall- and event-free survival was poorer in patients with SVT (Figure 1)

EFS, event-free survival; OS, overall survival; SVT, splanchnic vein thrombosis.
*Data from Garrote, et al.¹

Key learnings

Patients with SVT had shorter overall and event-free survival compared with patients, matched by age and sex without SVT. Molecular high-risk status was associated with the development of thrombotic events in patents with SVT. Clinical characteristics differ in patients with SVT, depending on whether SVT occurred at diagnosis or during follow-up; therefore, establishing the presence of SVT in younger patients allows for risk assessment for thrombosis and disease progression.