Outcomes of splanchnic vein thrombosis in patients with myeloproliferative neoplasms in a single center experience

Genomic classification and outcomes of young patients with polycythemia vera and essential thrombocythemia according to the presence of splanchnic vein thrombosis and its chronology

To elucidate the role of splanchnic vein thrombosis (SVT) and genomic characteristics in prognosis and survival, we compared patients with polycythemia vera (PV) or essential thrombocythemia (ET) presenting SVT at diagnosis (n = 69, median age 43 years) or during follow-up (n = 21, median age 46 years) to a sex- and age-matched control group of PV/ET without SVT (n = 165, median age 48 years). The majority of patients presenting with SVT at diagnosis were classified as myeloproliferative neoplasm with heterozygous JAK2 mutation (87% of cases vs. 69% in PV/ET control group, p < 0.05), characterized by low JAK2 allele burden and no high-risk mutations. Despite this lower molecular complexity, patients presenting with SVT showed a higher risk of death (HR 3.0, 95% CI 1.5-6.0, p = 0.003) and lower event-free survival (HR 3.0, 95% CI 1.9-4.8, p < 0.001) than age- and sex-matched PV/ET controls. In patients presenting with SVT, molecular high-risk was associated with increased risk of venous re-thrombosis (HR 5.8, 95% CI 1.4-24.0, p = 0.01). Patients developing SVT during follow-up were more frequently allocated in molecular high-risk than those with SVT at diagnosis (52% versus 13%, p < 0.05). In the whole cohort of patients, molecular classification identified PV/ET patients at higher risk of disease progression whereas DNMT3A/TET2/ASXL1 mutations were associated with higher risk of arterial thrombosis. In conclusion, clinical and molecular characteristics are different in PV/ET patients with SVT, depending on whether it occurs at diagnosis or at follow-up. Molecular characterization by NGS is useful for assessing the risk of thrombosis and disease progression in young patients with PV/ET.

The molecular landscape of myeloproliferative neoplasms associated with splanchnic vein thrombosis: Current perspective

BCR::ABL1-negative myeloproliferative neoplasms (MPNs) are classically represented by polycythemia vera, essential thrombocythemia, and primary myelofibrosis. BCR::ABL1-negative MPNs are significantly associated with morbidity and mortality related to an increased risk of thrombo-hemorrhagic events. They show a consistent association with splanchnic vein thrombosis (SVT), either represented by the portal, mesenteric or splenic vein thrombosis, or Budd-Chiari Syndrome. SVT is also a frequent presenting manifestation of MPN. MPNs associated with SVT show a predilection for younger women, high association with JAK2V617F mutation, low JAK2V617F variant allele frequency (generally <10 %), and low rates of CALR, MPL, or JAK2 exon 12 mutations. Next-Generation Sequencing techniques have contributed to deepening our knowledge of the molecular landscape of such cases, with potential diagnostic and prognostic implications. In this narrative review, we analyze the current perspective on the molecular background of MPN associated with SVT, pointing as well future directions in this field.

Splanchnic Vein Thrombosis in Myelofibrosis-An Underappreciated Hallmark of Disease Phenotype

Splanchnic vein thrombosis (SVT) encompasses thrombosis in the vessels of the splanchnic basin and has a relatively rare occurrence with a reported frequency in the general population of 1-2%. An episode of seemingly unprovoked SVT almost always triggers a diagnostic work-up for a Philadelphia chromosome-negative myeloproliferative neoplasm (MPN), since atypical site thrombosis is a hallmark of MPN-associated thrombophilia. Primary myelofibrosis (PMF) is a rare MPN with an estimated incidence between 0.1 and 1/100,000 per year. Although prothrombotic tendency in PMF is not envisioned as a subject of specific therapeutic management, unlike other MPNs, such as polycythemia vera (PV) and essential thrombocythemia (ET), thrombotic risk and SVT prevalence in PMF may be comparably high. Additionally, unlike PV and ET, SVT development in PMF may depend more on procoagulant mechanisms involving endothelium than on blood cell activation. Emerging results from registry data also suggest that PMF patients with SVT may exhibit lower risk and better prognosis, thus highlighting the need for better thrombotic risk stratification and identifying a subset of patients with potential benefit from antithrombotic prophylaxis. This review highlights specific epidemiological, pathogenetic, and clinical features pertinent to SVT in myelofibrosis.

Splanchnic Vein Thrombosis in Myeloproliferative Neoplasms: Treatment Considerations and Unmet Needs

Patients who develop splanchnic vein thrombosis (SVT) in the setting of a myeloproliferative neoplasm (MPN) are at risk for complications including portal hypertension, bleeding, thrombosis, and death. Prompt multidisciplinary treatment is thus necessary to prevent long-term sequelae. However, optimal management strategies are not well established due to a paucity of data. In this review, we very briefly discuss the epidemiology, pathophysiology, and prognosis of MPN-SVT and then more comprehensively explore treatment considerations of MPN-SVT, including anticoagulation, endovascular/surgical intervention, and cytoreductive therapy. We will also highlight current gaps in our knowledge of MPN-SVT and conclude by suggesting future directions to optimize the treatment of MPN-SVT and improve outcomes.

Primary Myelofibrosis in the Prefibrotic Stage Presenting as Portal, Splenic, and Superior Mesenteric Vein Thrombosis: A Case Report and Review of the Literature

INTRODUCTION

Myeloproliferative neoplasms are the most common cause of splanchnic vein thrombosis in the absence of cirrhosis or nearby malignancy.

CASE PRESENTATION

A 31-year-old male presented to the emergency department with epigastric pain associated with mild thrombocytosis and elevated levels of aminotransferases, lactate dehydrogenase, and C-reactive protein. Contrast-enhanced abdominal computed tomography revealed splanchnic venous thrombosis that involved the portal, splenic, and superior mesenteric veins, without signs of chronic liver disease. Anticoagulation with warfarin was immediately started. Diagnostic work-up was remarkable for the presence of the JAK2 V617T mutation and hypercellular bone marrow, with increased myeloid cells and atypical megakaryocytes, consistent with primary myelofibrosis in a prefibrotic stage. No other hypercoagulable conditions were identified.

DISCUSSION

We present a rare case of primary myelofibrosis in the prefibrotic stage presenting as portal-splenic-superior mesenteric vein thrombosis. This demonstrates that extensive splanchnic vein thrombosis may be the onset manifestation of myeloproliferative neoplasms, even in early stages and in the absence of concomitant hypercoagulable conditions. The presence of the JAK2 mutation is an important prothrombotic risk factor that can, per se, contribute to large venous thrombosis.

Anticoagulation management post-transjugular intrahepatic portosystemic shunt in portal hypertension associated with myeloproliferative neoplasms

Portal hypertension (pHTN) complicates myeloproliferative neoplasms (MPNs), and usually occurs due to Budd-Chiari syndrome or splanchnic vein thrombosis. Current management modalities for MPN-associated pHTN include anticoagulation, transjugular intrahepatic portosystemic shunt (TIPS), and orthotopic liver transplant. Data on the thrombotic and bleeding outcomes of this practice is of poor quality, and whether direct oral anticoagulants (DOACs) are effective in this setting is unknown. We describe failure of DOACs to prevent post-TIPS complications in two case reports of patients with MPN-associated pHTN and review the associated literature. We conducted a comprehensive search in Embase (embase.com), Scopus (scopus.org), and PubMed for existing data on MPN-associated pHTN post-TIPS procedure. Four studies (n = 251) of patients with pHTN post-TIPS were eligible (MPN, n = 143). A review of the literature suggests that patients with MPN-associated pHTN may be at higher risk for post-TIPS complications including stent thrombosis and stenosis, compared with other causes of thrombotic pHTN. DOAC use has not been studied in this setting. While further studies to guide optimal management of MPN-associated pHTN post-TIPS are needed, available evidence suggests that life-long anticoagulation is warranted. DOACs should not be considered standard of care because of lack of evidence of efficacy.

Overview of Myeloproliferative Neoplasms: History, Pathogenesis, Diagnostic Criteria, and Complications

Myeloproliferative disorders are a group of diseases morphologically linked by terminal myeloid cell expansion that frequently evolve from one clinical phenotype to another and eventually progress to acute myeloid leukemia. Diagnostic criteria for the Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) have been established by the World Health Organization and they are recognized as blood cancers. MPNs have a complex and incompletely understood pathogenesis that includes systemic inflammation, clonal hematopoiesis, and constitutive activation of the JAK-STAT pathway. Complications, such as thrombosis and progression to overt forms of myelofibrosis and acute leukemia, contribute significantly to morbidity and mortality of patients with MPN.

Evaluation of Therapeutic Strategies to Reduce the Number of Thrombotic Events in Patients With Polycythemia Vera and Essential Thrombocythemia

Thrombosis is the largest contributor to morbidity and mortality in patients with polycythemia vera (PV) and essential thrombocythemia (ET). Our understanding of the risk factors and pathophysiology of thrombosis in PV and ET patients is developing, including recent insights into the role of aberrant platelet-neutrophil interactions, JAK2 mutated endothelial cells and the pro-thrombotic inflammatory milieu. To date, few available therapies have demonstrated the ability to reduce the thrombotic burden in patients with these diseases. Although numerous therapeutic agents have been investigated in both PV and ET patients, few studies are designed to assess their impact on thrombotic events. In this review, we first describe the burden of thrombosis in patients with these myeloproliferative neoplasms (MPNs) and briefly explore their pathophysiologic mechanisms. We then critically assess and summarize the evidence behind currently available therapies with attention toward thrombotic endpoints. Finally, we describe a path forward for clinical research in MPNs that involves surrogate endpoint validation, biomarker development, and clinical trial design strategies in order to accurately assess reduction of thrombotic events when evaluating novel therapies.

Outcomes of long-term anticoagulant treatment for the secondary prophylaxis of splanchnic venous thrombosis

BACKGROUND

Splanchnic vein thrombosis (SVT) is an uncommon but potentially life-threatening disease usually related to different underlying clinical conditions. The risk of SVT recurrences is high over time in patients with an underlying permanent prothrombotic condition. Vitamin K antagonists (VKA) represent the mainstay of treatment for SVT. Data about the efficacy and safety of direct oral anticoagulants (DOACs) are reported in the literature for the treatment of acute SVT, but less is known about their application for the secondary prophylaxis of venous thromboembolism (VTE). The aim of this study was to assess the efficacy and safety of long-term DOACs therapy in patients at high-risk of thrombosis, compared to VKA.

METHODS

This is a retrospective single-centre study including 70 patients with SVT on long-term anticoagulant treatment with VKA followed-up at our Units between January 2017 and December 2019. All the patients were at high thrombotic risk defined as the presence of a permanent prothrombotic condition requiring long-term anticoagulation. During follow-up, 28 patients were shifted to DOACs and their clinical outcomes were compared to those of the patients who continued VKA therapy. All the arterial and venous thrombotic events of the splanchnic and extra-splanchnic districts as well as the haemorrhagic adverse events occurring during follow-up were recorded.

RESULTS

Of the seventy patients enrolled in the study, 36 patients (51.4%) had a single-segment involvement thrombosis (28.5% of portal vein, 7.1% of superior mesenteric vein, 4.3% of splenic vein, 11.5% of hepatic veins) and 34 patients (48.6%) had multi-segment involvement at the time of diagnosis. 42 patients (60%) continued VKA therapy and 28 (40%) were switched to DOACs. Median follow-up was 6 years (range 2-8) during VKA and 1.9 years (range 1-5.2) during DOACs. The incidence of thrombotic events was similar between patients on VKA and those on DOACs. Patients on VKA developed deep vein thrombosis (DVT), and of the patients on DOACs 1 developed NSTEMI and 1 DVT. No major haemorrhagic events occurred. Minor bleedings occurred in 26% of patients on VKA and in none of the DOACs patients (P: 0.09).

CONCLUSIONS

Our results highlight that DOACs could represent an effective and safe alternative to the VKA for secondary prophylaxis in SVT patients at high risk of thrombosis.

The utility of thrombophilia testing in patients with newly diagnosed portal vein thrombosis

: Thrombophilia testing is frequently performed in both seemingly provoked and unprovoked portal vein thrombosis (PVT), yet the clinical implications of these expensive laboratory tests are unknown. We investigated the frequency of clinical management changes in patients with newly diagnosed PVT. This is a retrospective analysis of adult patients with a newly diagnosed PVT at a single institution. The primary outcome is change in clinical management, defined as documented change in choice, dose, or duration of anticoagulation, future thromboprophylaxis, or counseling of asymptomatic family members. Five-hundred and forty-four patients with PVT were identified, 438 (80.5%) of whom had an identifiable pretesting provoking factor, most commonly cirrhosis (39.2%). Two-hundred ninety-one patients (53.5%) had at least one hypercoagulable laboratory test performed. The most frequently positive test was PAI-1 polymorphism, followed by elevated homocysteine and MTHFR mutational analysis. However, the only test that was frequently positive and consistently altered management was JAK2 mutational analysis (15.3%). Factor V Leiden was commonly positive but rarely changed clinical decision-making (1.5%), as was flow cytometric testing for paroxysmal nocturnal hemoglobinuria (0.8%), and antiphospholipid antibodies (0.7%). Patients with cirrhosis rarely had thrombophilia testing results that were clinically significant. A rough cost estimate was dramatically reduced from $231 000 to $76 000 if only clinically meaningful tests were employed in the hypercoagulable work-up. These results highlight the need for focused thrombophilia testing in patients with PVT.