Antithrombotic Treatment of Splanchnic Vein Thrombosis: Results of an International Registry
Authors: Ageno Walter , Riva Nicoletta , Bang Soo-Mee , Sartori Maria Teresa , Grandone Elvira , Beyer-Westendorf Jan , Barillari Giovanni , Minno Matteo ND Di , Duce Rita , Malato Alessandra , Santoro Rita , Poli Daniela , Verhamme Peter , Martinelli Ida , Kamphuisen Pieter W. , Alatri Adriano , Oh Doyeun , Amico Elbio D. , Schulman Sam , Dentali Francesco 
Published: October 2019

Abstract
Abstract 499

Background:
Treatment of splanchnic vein thrombosis (SVT) is a clinical challenge due to heterogeneity of clinical presentations, increased bleeding risk and lack of evidences from clinical trials. We carried out an international registry aimed to describe current treatment strategies and factors associated with therapeutic decisions in a large prospective cohort of SVT patients.

Methods:
Between May 2008 and January 2012, consecutive SVT patients were enrolled in the registry and information on clinical presentation, risk factors, and therapeutic strategies was collected in an electronic database. Clinical outcomes during the first month of treatment were documented. A two-year follow up is ongoing.

Results:
613 patients from 12 countries were enrolled in the registry. Mean age was 53.1 (SD ± 14.8) years (range 16–85); 62.6% were males, 74.4% Caucasians. SVT occurred in the portal vein in 470 patients, in the mesenteric vein in 266, in the splenic vein in 139, and in the supra-hepatic veins in 56; 38.8% of patients had multiple vein segments involved. In 29.8% of patients SVT diagnosis was incidental. Most common risk factors included cirrhosis (27.8%), solid cancer (22.3%), intra-abdominal inflammation/infection (11.5%), surgery (8.9%), and myeloproliferative neoplasm (MPN)(8.2%); in 27.6% of patients SVT was idiopathic.
During the acute phase, 471 (76.8%) patients were treated with anticoagulant drugs: unfractionated heparin (10.4%), low molecular weight heparin or fondaparinux (66.4%), vitamin K antagonists (VKA) (48.5%). Four patients received aspirin, 9 received thrombolysis. A total of 135 patients (22.0%) remained untreated. Of patients with incidentally diagnosed SVT, 61.1% received anticoagulant treatment.
Incidental diagnosis (p<0.0001), single vein thrombosis (p<0.0001), gastrointestinal bleeding (p0.008), thrombocytopenia (p0.0003), cancer (p0.009) and cirrhosis (p<0.0001) were significantly associated with no anticoagulant treatment. History of venous thrombosis (p0.003), myeloproliferative neoplasm (p0.003), surgery (p0.001), and hormonal treatment (p0.013) were significantly associated with the use of anticoagulant treatment.
Decision to start patients on VKA was significantly associated with younger age (p<0.0001), symptomatic onset (p<0.0001), multiple veins involvement (p0.012) and unprovoked thrombosis (p<0.0001). Continued treatment with parenteral anticoagulants was significantly associated with anaemia (p0.013), thrombocytopenia (p<0.0001), cancer (p<0.0001), and cirrhosis (p<0.0001).
During the first month after diagnosis, 2 patients on anticoagulant treatment (0.4%) and 3 untreated patients (2.2%) had thrombosis extension, 2 (0.4%) treated and 2 (1.5%) untreated patients had major bleeding, 11 patients died (7 and 4, respectively).

Conclusions:
Despite the increased bleeding risk and recent guidelines suggesting not to treat incidentally detected SVT, 76.8% of newly diagnosed SVT receive anticoagulant therapy in clinical practice. Treatment strategies vary according to patients characteristics, with this patient selection resulting safe and effective during the acute phase of therapy. The ongoing two-year follow up will provide additional information.

Disclosures:
No relevant conflicts of interest to declare.