Incidence and factors predictive of recurrent thrombosis in people with non-cirrhotic portal vein thrombosis

Etiology and Risk Factors for Splanchnic Vein Thrombosis in Non-Cirrhotic, Non-Neoplastic Patients: A Narrative Review

Splanchnic vein thrombosis (SVT) is a heterogeneous group of disorders affecting the portal, mesenteric, splenic, and hepatic veins. While frequently associated with liver cirrhosis and malignancy, SVT also occurs in non-cirrhotic, non-neoplastic patients. This narrative review evaluates the epidemiology and risk factors for SVT in this population. The prevalence and incidence of SVT in non-cirrhotic, non-neoplastic patients remain incompletely characterized, with estimates varying widely across studies. The clinical significance of SVT relates to potential complications, including intestinal ischemia, portal hypertension, and a possible underlying systemic disorder. Risk factors for SVT can be categorized into local abdominal conditions, thrombophilias, and systemic disorders. Local factors include inflammatory bowel disease, pancreatitis, abdominal surgery, and trauma. Thrombophilias, both inherited and acquired, are significant contributors to SVT risk. Systemic conditions associated with SVT include autoimmune disorders, pregnancy, hematological diseases, and infections. The complex interplay of these risk factors highlights the need for a comprehensive evaluation of SVT patients. Early recognition and management of these conditions can prevent potentially life-threatening complications and guide decisions regarding anticoagulation and long-term follow-up.

Anticoagulation for splanchnic vein thrombosis in acute pancreatitis increases bleeding risk without improving outcomes

BACKGROUND/OBJECTIVES

Treatment guidelines on anticoagulation (AC) to treat splanchnic vein thrombosis (SVT) after acute pancreatitis (AP) are not well-established. This research examines the efficacy and safety of AC in SVT.

METHODS

We retrospectively investigated the demographics, clinical progression, radiologic findings, interventions, and outcomes of patients with AP between 2018 and 2022 at a single tertiary care center. The primary and secondary outcomes were development of SVT in AP and effects of AC, respectively.

RESULTS

897 patients developed AP (average 50.5 years old, 46% female, 20% moderately severe AP, 4% severe AP), of whom 4.8% developed SVT. SVT was associated with recurrent and chronic pancreatitis (28%, p = 0.021 and 37%, p < 0.001) and malignancy (21%, p < 0.001). SVT was associated with severe pancreatitis courses (12% vs. 3%, p < 0.001) and an increase in six-month mortality (14% vs. 4%, p = 0.022). AC was used for 47% of patients with SVT. However, AC did not prevent SVT sequelae, including gastroesophageal varices formation (p = 1), variceal hemorrhage (p = 0.68), or splenic infarction (p = 1), and did not improve survival (p = 0.19). While AC did not improve outcomes, it was associated with bleeding episodes in 50% of patients (p < 0.001).

CONCLUSIONS

Approximately half of patients who develop SVT after AP receive AC despite no reduction in adverse events or mortality. Additionally, half of patients receiving AC experience bleeding complications. The limited evidence presented in this study suggests that the risks of AC for SVT in AP may outweigh its benefits and highlights the need for future studies in larger prospective cohorts.

Portal Vein Thrombosis in Patients Without Cirrhosis: Current Practical Approaches and Treatment Strategies

Portal vein thrombosis in non-cirrhotic individuals, although uncommon, is an increasingly explored condition that affects mainly young people, consequently representing a significant disease burden. Reports primarily including western European populations have recently shed light regarding the pathophysiology, risk factors, natural history, treatment, and prognosis of this entity. Underlying predisposing conditions are documented in ~70% of cases, encompassing local risk factors, inherited and acquired thrombophilia, cancer, and systemic inflammatory conditions. Non-cirrhotic portal vein thrombosis can cause significant portal hypertension in the acute setting, but, more frequently, significant portal hypertension-related complications arise when the condition becomes chronic and portosystemic collaterals develop, increasing the risk for variceal bleeding and ascites. The diagnostic approach to screen for underlying thrombophilia remains a challenge, and recommendations in this regard, although scarce and backed by scarce evidence, have changed notably in the last years, leaning toward a universal screen in patients who develop this condition without a clear provoking factor. Recently, studies have shown that long-term anticoagulation may be appropriate even in the absence of clear provoking factors or underlying thrombophilia. Future studies should address which patients may benefit from this approach, which patients may not need it, and what the most appropriate strategies are to approach patients who do not recover portal vein patency with anticoagulation to further prevent portal hypertension-related complications.

Clinical spectrum and long-term outcomes of non-cirrhotic portal venous system thrombosis in Hispanic population

INTRODUCTION AND OBJECTIVES

Portal venous system thrombosis (PVT) outside the setting of cirrhosis is uncommon with limited information available about the etiological and clinical characteristics across varied racial and ethnic groups.

MATERIALS AND METHODS

This retrospective cohort study examines the long-term outcomes of non-cirrhotic, Hispanic adults diagnosed with PVT at a single center in Mexico City between January 2000 and August 2023. Patients with conditions predisposing to PVT were excluded.

RESULTS

We included 100 Hispanic adults diagnosed with non-cirrhotic PVT. Thrombophilia was identified in 49 %, with antiphospholipid syndrome (APS) being the most prevalent thrombophilia (23 %), followed by JAK2 mutation (18 %). Chronic PVT, observed in 70 % of cases, predominantly affected the portal vein (50 %), followed by porto-mesenteric (41 %) and porto-splenic (9 %) territories. At diagnosis, 55 % had esophageal varices. Anticoagulant therapy was administered to over half of the patients for >12 months. Over a median follow-up of 55 months, the 5-year risk of re-thrombosis was 24 %, and the 5-year risk of variceal bleeding (VB) was 45 %. The 4-year overall survival (OS) was 97 %. Comparative analysis between thrombophilia-associated and idiopathic PVT did not reveal significant differences in VB, re-thrombosis, and OS.

CONCLUSIONS

This study underscores the unique clinical profile of Hispanic patients with non-cirrhotic PVT, highlighting a high prevalence of APS and substantial risks of VB. These findings contribute to a better understanding of PVT in Hispanics and emphasize the importance of tailored management strategies. The generalizability of our results may be limited by the thrombophilia testing approach, the excluded populations, and its retrospective, single center nature.

Portal hypertension: recommendations for diagnosis and treatment. Consensus document sponsored by the Spanish Association for the Study of the Liver (AEEH) and the Biomedical Research Network Centre for Liver and Digestive Diseases (CIBERehd)

Portal hypertension is a hemodynamic abnormality that complicates the course of cirrhosis, as well as other diseases that affect the portal venous circulation. The development of portal hypertension compromises prognosis, especially when it rises above a certain threshold known as clinically significant portal hypertension (CSPH). In the consensus conference on Portal Hypertension promoted by the Spanish Association for the Study of the Liver and the Hepatic and Digestive diseases area of the Biomedical Research Networking Center (CIBERehd), different aspects of the diagnosis and treatment of portal hypertension caused by cirrhosis or other diseases were discussed. The outcome of this discussion was a set of recommendations that achieved varying degrees of consensus among panelists and are reflected in this consensus document. The six areas under discussion were: the relevance of CSPH and the non-invasive methods used for its diagnosis and that of cirrhosis, the prevention of the first episode of decompensation and its recurrence, the treatment of acute variceal bleeding and other complications of portal hypertension, the indications for the use of TIPS, and finally, the diagnosis and treatment of liver vascular diseases.

Portal hypertension: recommendations for diagnosis and treatment. Consensus document sponsored by the Spanish Association for the Study of the Liver (AEEH) and the Biomedical Research Network Center for Liver and Digestive Diseases (CIBERehd)

Portal hypertension is a hemodynamic abnormality that complicates the course of cirrhosis, as well as other diseases that affect the portal venous circulation. The development of portal hypertension compromises prognosis, especially when it rises above a certain threshold known as clinically significant portal hypertension (CSPH). In the consensus conference on Portal Hypertension promoted by the Spanish Association for the Study of the Liver and the Hepatic and Digestive diseases area of the Biomedical Research Networking Center (CIBERehd), different aspects of the diagnosis and treatment of portal hypertension caused by cirrhosis or other diseases were discussed. The outcome of this discussion was a set of recommendations that achieved varying degrees of consensus among panelists and are reflected in this consensus document. The six areas under discussion were: the relevance of clinically significant portal hypertension and the non-invasive methods used for its diagnosis and that of cirrhosis, the prevention of the first episode of decompensation and its recurrence, the treatment of acute variceal bleeding and other complications of portal hypertension, the indications for the use of TIPS, and finally, the diagnosis and treatment of liver vascular diseases.

Impact of SARS-CoV-2 vaccination in patients with vascular liver diseases: Observations from a VALDIG multicenter study

Background & Aims

Patients with vascular liver diseases (VLD) are at higher risk of both severe courses of COVID-19 disease and thromboembolic events. The impact of SARS-CoV-2 vaccination in patients with VLD has not been described and represents the aim of our study.

Methods

International, multicenter, prospective observational study in patients with VLD analyzing the incidence of COVID-19 infection after vaccination, severity of side effects, occurrence of thromboembolic events and hepatic decompensation. In a subgroup of patients, the humoral and cellular responses to vaccination were also analyzed.

Results

A total of 898 patients from 14 European centers - part of the VALDIG network - were included, 872 (97.1%) patients received two vaccine doses (fully vaccinated), and 674 (75.1%) three doses. Of the total cohort, 151/898 had a COVID-19 infection prior to vaccination, of whom 9/151 (5.9%) were re-infected. Of the 747/898 patients who were not previously infected, 11.2% (84/747) were diagnosed with a COVID-19 infection during the study period. Two infected patients required intensive care unit admission and infection was fatal in two fully vaccinated patients. Adverse effects were reported in around 40% of patients, with local side effects being the most frequent. During the study period, 31 (3.5%) patients had thromboembolic events and 21 (2.3%) hepatic decompensations. No cases of vaccine-induced thrombocytopenia were reported. Vaccine immunogenicity was assessed in 36 patients; seroconversion reached 100% and IFNy T-cell responses significantly increased post two mRNA-1273 vaccine doses.

Conclusion

Patients with VLD seem to have a preserved immune response to SARS-CoV-2 vaccination, which appears to be safe and effective in preventing severe COVID-19 infection. Our study cannot definitively establish a direct link between vaccination and thrombotic events, though the contribution of vaccination as a cofactor in VLD remains to be elucidated.

Impact and implications

Patients with vascular liver disease (VLD) are at increased risk of both SARS-CoV-2 infection and severe COVID-19 disease. The potential risks associated with vaccination against this infection need thorough investigation. Our research enhances the understanding of the effects of COVID-19 vaccination in patients with VLD, highlighting its good tolerability. Moreover, patients with VLD appear to have a preserved immune response to SARS-CoV-2 vaccination, providing protection against severe COVID-19 infection. Our study cannot definitively establish a direct link between vaccination and thrombotic events, and no cases of vaccine-induced thrombocytopenia were reported.

Management of Portal vein Thrombosis in Cirrhosis

Portal vein thrombosis (PVT) is one of the common complications of cirrhosis. The incidence of PVT correlates with liver disease severity-higher incidence in patients with Child-Turcotte-Pugh (CTP) C, large spontaneous portosystemic shunts, hepatofugal portal flow, and in the presence of hepatocellular carcinoma. PVT may worsen ascites, increase the risk and poor control of variceal bleeding. The occurrence of PVT may increase morbidity and lower survival after a liver transplant. Using statins prevents the occurrence of PVT, whereas beta-blockers may aggravate its occurrence. Cross-sectional imaging is mandatory for the precise diagnosis and classification of PVT. Symptomatic, occlusive PVT and candidacy for liver transplantation are the main indications for anticoagulation. Vitamin K antagonists, low-molecular-weight heparin, and newer anticoagulants are effective and safe in cirrhosis. Direct-acting oral anticoagulants are agents of choice in early cirrhosis (CTP A, B). The duration of anticoagulant therapy, predictors of response, and management of complications of cirrhosis while on therapy require in-depth knowledge and individualized treatment. Transjugular intrahepatic porto-systemic shunt can be considered in nonresponsive cases or when anticoagulants are contraindicated. This manuscript reviews the latest updated knowledge about managing PVT in cirrhosis.

Effect of factor VIII and FVIII/PC ratio on portal vein thrombosis in liver cirrhosis: a systematic review and meta‑analysis

BACKGROUND

To date, there is an ongoing debate regarding the ability to predict PVT development using markers of FVIII or FVIII/PC ratio. This study presents evidence-based medical findings on the influence of FVIII activity levels and FVIII/PC values in the formation of PVT in cirrhosis.

METHODS

The search for original studies on risk factors for portal vein thrombosis (PVT) associated with cirrhosis was conducted, which primarily focused on comparing circulating FVIII activity levels or FVIII/PC ratio in cirrhotic patients with and without PVT. The quality of evidence from each study was assessed using the Newcastle-Ottawa Scale.

RESULTS

The meta-analysis included a total of 10 original studies. In total, 2250 cirrhotic patients were included, with 414 having PVT and 1836 without PVT. The pooled analysis using a random-effects model showed no significant difference in standardized mean difference (SMD) for FVIII activity levels in cirrhotic patients with or without PVT (SMD = 0.12, 95% CI=-0.46 to 0.70, P = 0.68), but there was significant heterogeneity (I2 = 95.52%, P = 0.00). Meta-regression analysis indicated that differences in mean FVIII activity levels in the PVT group, the number of cases in the non-PVT group, and the study design methods partially contributed to the heterogeneity (P < 0.05). However, compared to the non-PVT group, the PVT group had higher FVIII/PC ratio with a statistically significant difference (SMD = 0.39, 95% CI: 0.15 to 0.63, P = 0.00), and there was no significant heterogeneity (I2 = 28.62%).

CONCLUSION

In conclusion, the FVIII/PC ratio not only reflects the severity of liver disease, but also can be used as one of the predictors of PVT development.

Portal Vein Recanalization Transjugular Intrahepatic Portosystemic Shunt for Noncirrhotic Chronic Portal Vein Thrombosis Leading to Successful Pregnancy: Case Report

Portal vein recanalization transjugular intrahepatic portosystemic shunt (PVR-TIPS) is a safe and effective procedure for decompression of portal hypertension (PH). In this short case series, 2 women with chronic noncirrhotic portal vein thrombosis were treated with PVR-TIPS. Both patients hoped to conceive. Without treatment for their PH, their pregnancies posed a significant risk of life-threatening variceal bleeding. Both patients tolerated the procedure well and delivered without complications of PH. In future cases of noncirrhotic portal vein thrombosis in patients hoping to conceive, PVR-TIPS should be considered for definitive treatment of PH.

Recurrent splanchnic and extrasplanchnic thrombotic events in patients with non-cirrhotic portal vein thrombosis associated with local factors

BACKGROUND & AIMS

One-third of non-cirrhotic portal vein thrombosis (NCPVT) cases are associated with local factors. The risk of rethrombosis after anticoagulation withdrawal is unknown. We aimed to determine factors associated with new splanchnic or extrasplanchnic thrombotic events in this setting.

METHODS

We performed a retrospective study including cases of recent NCPVT associated with local factors. High- and low-risk prothrombotic factors, prespecified according to RIPORT study criteria, were assessed. Univariate and multivariate Cox models assessed the influence of different variables on the occurrence of new thrombotic events.

RESULTS

At baseline, 83/154 (53.9%) patients had at least one prothrombotic factor including 50 (32.5%) with a high-risk and 33 (21.4%) with a low-risk prothrombotic factor. Oestrogen-containing contraception was discontinued in all patients. During follow-up, 63/140 (45%) patients had at least one prothrombotic factor, including 47 (33.6%) with a high-risk and 16 (11.4%) with a low-risk prothrombotic factor. Seventeen new thrombotic events occurred after a median follow-up of 52 (IQR 14-62) (min-max 3.0-69.0) months. New thromboses were associated with high-risk factors (hazard ratio [HR] 3.817, 95% CI 1.303-11.180, p = 0.015), but were inversely related to recanalization (HR 0.222, 95% CI 0.078-0.635, p = 0.005) and anticoagulation (HR 0.976, 95% CI 0.956-0.995, p = 0.016). When a high-risk factor was present a new thrombotic event occurred in 7.4%, 14.6%, 14.6% and 28.8% of patients at 1, 3, 5 and 7 years under anticoagulants, respectively, compared to 21.2%, 21.2%, 58% and 58% without anticoagulants, respectively.

CONCLUSIONS

In cases of recent NCPVT associated with local factors, high-risk factors for thrombosis are associated with new thrombotic events. Permanent anticoagulation appears beneficial in this high-risk situation.

IMPACT AND IMPLICATIONS

In non-cirrhotic portal vein thrombosis (NCPVT) associated with local factors, systematic screening for prothrombotic factors is recommended, but the prevalence of the latter is not clearly established, and the risk of recurrent intra or extrasplanchnic thromboembolism is poorly described. Thus, interest in permanent anticoagulation remains. NCPVT associated with local factors is a matter of concern for hepatologists, gastroenterologists and digestive surgeons. Due to a lack of knowledge, practices are heterogeneous. Our findings highlight that systematic screening for prothrombotic factors in NCPVT is needed even when associated with local factors, as it may justify long-term anticoagulation for the prevention of new intra or extrasplanchnic thrombotic events in at least one-third of cases. The interest in long-term anticoagulation should be investigated prospectively in the absence of high-risk prothrombotic factors.

CLINICAL TRIAL NUMBER

NCT0536064.

Portal vein thrombosis: diagnosis, management, and endpoints for future clinical studies

Portal vein thrombosis (PVT) refers to the development of a non-malignant obstruction of the portal vein, its branches, its radicles, or a combination. This Review first provides a comprehensive overview of all aspects of PVT, namely the specifics of the portal venous system, the risk factors for PVT, the pathophysiology of portal hypertension in PVT, the interest in non-invasive tests, as well as therapeutic approaches including the effect of treating risk factors for PVT or cause of cirrhosis, anticoagulation, portal vein recanalisation by interventional radiology, and prevention and management of variceal bleeding in patients with PVT. Specific issues are also addressed including portal cholangiopathy, mesenteric ischaemia and intestinal necrosis, quality of life, fertility, contraception and pregnancy, and PVT in children. This Review will then present endpoints for future clinical studies in PVT, both in patients with and without cirrhosis, agreed by a large panel of experts through a Delphi consensus process. These endpoints include classification of portal vein thrombus extension, classification of PVT evolution, timing of assessment of PVT, and global endpoints for studies on PVT including clinical outcomes. These endpoints will help homogenise studies on PVT and thus facilitate reporting, comparison between studies, and validation of future studies and trials on PVT.

Porto-sinusoidal Vascular Disease: Classification and Clinical Relevance

Non-cirrhotic portal hypertension (NCPH) is a well-recognized clinico-pathological entity, which is associated with clinical signs and symptoms, imaging, and endoscopic features of portal hypertension (PHT), in absence of cirrhosis. In patients with NCPH without known risk factors of PHT or extrahepatic portal vein thrombosis, the condition is called idiopathic non-cirrhotic portal hypertension (INCPH). There are multiple infectious, immune related causes, systemic diseases, drug and toxin exposures, haematological disorders, and metabolic risk factors that have been associated with this INCPH. However, the causal pathogenesis is still unclear. The Vascular liver disorders interest group group recently proposed porto-sinusoidal vascular disease (PSVD) as a syndromic entity, which provides definite histopathological criteria for diagnosis of NCPH (table 1). The three classical histo-morphological lesions specific for PSVD include obliterative portal venopathy, nodular regenerative hyperplasia, and incomplete septal fibrosis. The PSVD definition includes patients with portal vein thrombosis, PVT, and even those without PHT, thus broadening the scope of diagnosis to include patients who may have presented early, prior to haemodynamic changes consistent with PHT. However, this new diagnosis has pros and cons. The cons include mandating invasive liver biopsy to assess the PSVD histological triad in all patients with NCPH, an erstwhile clinical diagnosis in Asian patients. In addition, the natural history of the subclinical forms of PSVD without PHT and linear progression to develop PHT is unknown yet. In this review, we discuss the diagnosis and treatment of INCPH/PSVD, fallacies and strengths of the old and new schema, pathobiology of this disease, and clinical correlates in an Asian context. Although formulation of standardised diagnostic criteria is useful for comparison of clinical cohorts with INCPH/PSVD, prospective clinical validation in global cohorts is necessary to avoid misclassification of vascular disorders of the liver.

Homozygous MTHFR C677T carriers develop idiopathic portal vein thrombosis 20 years earlier than wild type

The aim of this study was to evaluate the impact of methylene tetrahydrofolate reductase (MTHFR) rs1801133 (C→T667 transition) on age at first idiopathic portal vein thrombosis (PVT) and to identify clinical and/or laboratory variables influencing age at first PVT, including plasma homocysteine and the prothrombin rs1799963 PT (G→A transition at position 20210) (PT) mutation. A retrospective cross-sectional cohort, including 15 MTHFR TT, 32 MTHFR TC and 22 MTHFR CC idiopathic PVT participants contributing demographics, age at PVT, plasma concentrations of homocysteine and of natural anticoagulants. MTHFR TT carriers presented with a lower age at PVT than heterozygous or wild-type genotypes (31 ± 8 vs. 48 ± 15 vs. 52 ± 13 years, P  = 0.001) and were more likely to have a plasma HC concentration above the cut-off (73.3 vs. 32 vs. 50%, P  = 0.04). MTHFR TT and protein C predicted age at PVT ( P  < 0.0001 and P  = 0.06); MTHFR TT predicted plasma homocysteine ( P  = 0.05). In the MTHFR TT group, plasma homocysteine inversely related to protein C ( P  = 0.03). Plasma homocysteine predicted the extent of PVT ( P  = 0.03). Compound MTHFR TT + PT GA did not lower age at first PVT compared to MTHFR TT alone (35 ± 9 vs. 30 ± 8 years). MTHFR TT is associated with a 20-year earlier PVT presentation than heterozygous and wild-type MTHFR genotypes. The inverse relation between plasma homocysteine and protein C contributes to the prematurity of PVT in the MTHFR TT group, whereas plasma homocysteine contributes to the extent of PVT. The recent exclusion of MTHFR genotyping from the thrombophilia screen needs revisiting in this setting.

Current concepts in the management of non-cirrhotic non-malignant portal vein thrombosis

Non-cirrhotic non-malignant portal vein thrombosis (NCPVT) is an uncommon condition characterised by thrombosis of the portal vein, with or without extension into other mesenteric veins, in the absence of cirrhosis or intra-abdominal malignancy. Complications can include intestinal infarction, variceal bleeding and portal biliopathy. In this article, we address current concepts in the management of NCPVT including identification of risk factors, classification and treatment, and review the latest evidence on medical and interventional management options.

Transjugular Intrahepatic Portosystemic Shunt in Nonmalignant Noncirrhotic Portal Vein Thrombosis and Portosinusoidal Vascular Disorder

Transjugular intrahepatic portosystemic shunt (TIPS) emerges as a key treatment for portal hypertension (PH) complications. While international guidelines provide clear indications for its use in cirrhosis, empirical knowledge is notably scarcer in non-cirrhotic PH, particularly in nonmalignant noncirrhotic portal vein thrombosis (NNPVT) and in patients with portosinusoidal vascular disorder (PSVD). Patients afflicted by these rare diseases exhibit distinct clinical profiles compared to their cirrhotic counterparts, often characterized by a younger age, predominantly preserved hepatic functionality even in cases of severe PH, and a higher propensity for extensive splanchnic thrombosis, which intricately complicates TIPS placement, posing unique challenges for its creation. The objective of this review is to synthesize existing literature on the effectiveness, safety, specific indications, and clinical outcomes of TIPS in adult patients with NNPVT or PSVD, focusing also on the technical challenges of TIPS insertion in the presence of portal cavernoma.

Clinical outcomes and prognostic factors in non-cirrhotic non-neoplastic patients with portal vein thrombosis: A single-centre experience

INTRODUCTION

The knowledge of natural history and prognostic factors of portal vein thrombosis (PVT) is still based on a limited number of studies.

AIM

To describe our single-center experience with 79 consecutive non-neoplastic non-cirrhotic patients with PVT (15 recent/64 chronic PVT).

RESULTS

Among patients with recent PVT, 7 received anticoagulation alone, 4 systemic thrombolysis, 3 direct thrombolysis through a TIPS and 1 TIPS alone. Portal recanalization was achieved in 11 patients. In patients with chronic PVT, the rate of variceal progression was high (20% at one year and 50% at two years). The thrombotic involvement of splenic and superior mesenteric veins was the only risk factor for variceal enlargement. The cumulative bleeding rates were 10% at one year and 20% at two years. A multisegmental thrombosis and large varices at entry and a previous variceal bleeding were the independent predictors for variceal bleeding. The cumulative rate of new thrombotic events was 14% at one year and 18% at two years. Eight patients died, 2 because of thrombotic events. There were no bleeding-related deaths. Two-year cumulative survival rate was 90%.

CONCLUSIONS

Our study supports the importance of anticoagulation especially when a more extended thrombosis is present. Moreover, in patients with chronic PVT, the timing of follow-up endoscopy should be based on the extension of thrombosis and not, as in cirrhosis, on the size of varices at first endoscopy.

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.