Great Debates in Vascular Medicine: Extended duration anticoagulation for unprovoked venous thromboembolism - Coming to consensus when the debate rages on

PATHOPHYSIOLOGICAL MECHANISMS OF DEEP VEIN THROMBOSIS

Deep venous thrombosis is a frequent multifactorial disease and most of the time is triggered by the interaction between acquired risk factors, particularly immobility, and hereditary risk factors such as thrombophilias. The mechanisms underlying deep venous thrombosis are not fully elucidated; however, in recent years the role of venous flow, endothelium, platelets, leukocytes, and the interaction between inflammation and hemostasis has been determined. Alteration of venous blood flow produces endothelial activation, favoring the adhesion of platelets and leukocytes, which, through tissue factor expression and neutrophil extracellular traps formation, contribute to the activation of coagulation, trapping more cells, such as red blood cells, monocytes, eosinophils, lymphocytes. The coagulation factor XI-driven propagation phase of blood coagulation plays a major role in venous thrombus growth, but a minor role in hemostasis. In this work, the main mechanisms involved in the pathophysiology of deep vein thrombosis are described.

PROS1 variant c.1574C>T p.Ala525Val causes portal vein thrombosis with Protein S Deficiency

BACKGROUND

Protein S (PS) is a vitamin K-dependent plasma glycoprotein, and the deficiency of PS increases the risk of venous thromboembolism (VTE). PS deficiency has been found in 1.5-7% of selected groups of thrombophilic patients. However, the reported PS deficiency patients with portal vein thrombosis are scarce.

CASE REPORT AND RESULTS

Our case described a 60-year-old male patient presented portal vein thrombosis with protein S deficiency. Imaging findings of the patient revealed extensive thrombosis involving the portal vein and superior mesenteric vein. His medical history revealed lower extremity venous thrombosis 10 years ago. The level of PS activity was greatly reduced (14%, reference: 55-130%). Acquired thrombophilia caused by antiphospholipid syndrome, hyperhomocysteinemia, or malignancy were excluded. Whole exome sequencing revealed a heterozygous missense variation c.1574C>T, p.Ala525Val in the PROS1 gene. The in-silico analysis of the variant was performed by SIFT and PolyPhen-2. The results showed that the variant is a pathogenic and likely pathogenic variation respectively (SIFT, -3.404; PolyPhen-2, 0.892), the amino acid substitution A525V is presumed to result in unstable PS protein which is degraded intracellularly. Mutation site of the proband and his family members was validated by Sanger sequencing.

CONCLUSION

According to the clinical manifestation, imaging findings, protein S level, and the genetic results, a diagnosis of portal vein thrombosis with PS deficiency was made. To the best of our knowledge, our case is the second reported PS deficiency patient caused by PROS1 c.1574C>T, p.Ala525Val variant in Asia, and the case is also the only reported case with PROS1 c.1574C>T, p.Ala525Val variant presents portal vein thrombosis.

Inflammation, Infection and Venous Thromboembolism

The association between inflammation, infection, and venous thrombosis has long been recognized; yet, only in the last decades have we begun to understand the mechanisms through which the immune and coagulation systems interact and reciprocally regulate one another. These interconnected networks mount an effective response to injury and pathogen invasion, but if unregulated can result in pathological thrombosis and organ damage. Neutrophils, monocytes, and platelets interact with each other and the endothelium in host defense and also play critical roles in the formation of venous thromboembolism. This knowledge has advanced our understanding of both human physiology and pathophysiology, as well as identified mechanisms of anticoagulant resistance and novel therapeutic targets for the prevention and treatment of thrombosis. In this review, we discuss the contributions of inflammation and infection to venous thromboembolism.

Impact of multidisciplinary team meetings on the management of venous thromboembolism. A clinical study of 142 cases

OBJECTIVE

Numerous guidelines have been published on the management of venous thromboembolism (VTE). However, therapeutic decision-making may prove challenging in routine clinical practice. With this in mind, multidisciplinary team (MDT) meetings have been set up in Rennes University Hospital, France. This study sought to describe the situations discussed during MDT meetings and to assess whether the meetings bring about changes in the management of these patients.

MATERIALS AND METHODS

A retrospective single-center study conducted at the Rennes University Hospital included cases presented from the beginning of the MDT meetings (February 2015) up to May 2017.

RESULTS

In total, 142 cases were presented in 15 MDT meetings, corresponding to a mean of 10±4 cases per meeting. Of these, 129 related to VTE patients: 33 provoked VTEs, 22 unprovoked VTEs, 49 cancer-related VTEs, and 25 unspecified VTEs. MDT meetings led to significant changes in the anticoagulation type (therapeutic, prophylactic, or discontinuation) and duration, but not in the anticoagulant choice (direct oral anticoagulants, vitamin K antagonists, heparins, etc.).

CONCLUSION

Requests for MDT meetings are made for all VTE types, and these meetings have an impact on VTE management.

Risk Of Recurrence After Withdrawal Of Anticoagulation In Patients With Unprovoked Venous Thromboembolism: External Validation Of The Vienna Nomogram And The Dash Prediction Score

INTRODUCTION

Scales for predicting venous thromboembolism (VTE) recurrence are useful for deciding the duration of the anticoagulant treatment. Although there are several scales, the most appropriate for our setting has not been identified. For this reason, we aimed to validate the DASH prediction score and the Vienna nomogram at 12 months.

METHODS

This was a retrospective study of unselected consecutive VTE patients seen between 2006 and 2014. We compared the ability of the DASH score and the Vienna nomogram to predict recurrences of VTE. The validation was performed by stratifying patients as low-risk or high-risk, according to each scale (discrimination) and comparing the observed recurrence with the expected rate (calibration).

RESULTS

Of 353 patients evaluated, 195 were analyzed, with an average age of 53.5 ± 19 years. There were 21 recurrences in 1 year (10.8%, 95% CI: 6.8%-16%). According to the DASH score, 42% were classified as low risk, and the rate of VTE recurrence in this group was 4.9% (95% CI: 1.3%-12%) vs. the high-risk group that was 15% (95% CI: 9%-23%) (p <.05). According to the Vienna nomogram, 30% were classified as low risk, and the rate of VTE recurrence in the low risk group vs. the high risk group was 4.2% (95% CI:0.5%-14%) vs. 16.2% (95% CI: 9.9%-24.4%) (p <.05).

CONCLUSIONS

Our study validates the DASH score and the Vienna nomogram in our population. The DASH prediction score may be the most advisable, both because of its simplicity and its ability to identify more low-risk patients than the Vienna nomogram (42% vs. 30%).