Evaluation of the frequency, risk factors, and outcomes of splanchnic vein thrombosis in myeloproliferative neoplasms: a retrospective cohort study

Splanchnic vein thrombosis (SVT) is an uncommon but clinically significant complication of myeloproliferative neoplasms (MPNs), contributing to morbidity and management complexity. Evidence regarding prognostic factors and optimal anticoagulation strategies remains limited. We aimed to evaluate the clinical characteristics, risk factors, treatment strategies, and survival outcomes in patients with SVT associated with MPNs. In this multicenter retrospective cohort study, 289 adult patients with SVT associated with MPNs were analyzed. The median age at SVT diagnosis was 49 years, with 74% of patients < 60 years, indicating a predominance in younger individuals. Portal vein thrombosis was the most common presentation (87.5%). Over a median follow-up of 82 months, survival was significantly better in patients < 60 years (p < 0.01). In multivariable analysis, age ≥ 60 years and myelofibrosis were independent predictors of inferior survival (both p < 0.01), whereas early recanalization was not associated with survival. Bleeding complications occurred in 27% of anticoagulated patients, with no fatal events. Direct oral anticoagulants and vitamin K antagonists showed comparable bleeding profiles, although major bleeding was more frequent with vitamin K antagonists. Despite early recanalization, most patients continued long-term anticoagulation. In conclusion, MPN-associated SVT predominantly affects younger patients, underscoring an age-independent prothrombotic risk. Survival is primarily driven by age and disease subtype rather than thrombotic characteristics. Given the persistent thrombotic risk despite bleeding complications, long-term anticoagulation remains central to management and requires individualized decision-making. Prospective studies are needed to optimize treatment strategies.