Splanchnic vein thromboses associated with myeloproliferative neoplasms: An international, retrospective study on 518 cases

Myeloproliferative Neoplasms (MPN) course can be complicated by thrombosis involving unusual sites ads the splanchnic veins (SVT). Their management is challanging, given their composite vascular risk. We performed a retrospective, cohort study in the framework of the INternational Working Group fo MPN Research and Treatment (IWG-MRT),a nd AIRC- Group Italiano Malattie Mieloproliferative (AGIMM). A total of 518 MPN-SVT cases were collected and compared with 1628 unselected, control MPN population, mached for dysease type. Those with MPN-SVTwere younger (median 44 years) and enriched in females compared to controls; PV (37.1%) and ET (34.4%) were the most frequent diagnoses. JAK2V617F mutation was highly prevalent (90.2%) and 38.6% of cases had an additional hypercoagulable disorder. SVT recurrence rate was 1.6 per 100 patients-years. VItamin-K antagonist (VKA) halved the incidence of recurrence (OR 0.48), unlike cytoreduction (OR 0.96), and were not associated with overall or gastrointestinal bleeding in multivariable analysis. Esophageal varices were the only independent predictor for major bleeding (OR17.4): Among MPN-SVT, risk of subsequent vascular events was skwed towards venous thromboses compared to controls. However, MPN-SVT clinical course was overall benign: SVT were enriched in PMF with lower IPSS, resulting in significantly longer survival than controls; survival was not affected by PV and sightly reduced in ET. MPN-U with SVT (n=55) showed a particularly indolent phenotype, with no signs of disesase evolution. in the to-date largest, contemporary cohort of MPN-SVT, VKA were confirmed effective in preventing recurrence, unlike cytoreduction, and safe; the major risk factor for esophageal varices that therefore represent a major therapeutic target