Use of Micronized Purified Flavonoid Fraction Together with Rivaroxaban Improves Clinical and Ultrasound Outcomes in Femoropopliteal Venous Thrombosis: Results of a Pilot Clinical Trial

Risk of developing post thrombotic syndrome after deep vein thrombosis with different anticoagulant regimens: A systematic review and pooled analysis

BACKGROUND

Post-thrombotic syndrome (PTS) is common in patients with deep vein thrombosis (DVT). It is unclear if different types of anticoagulant therapies (e.g. vitamin K antagonists (VKA), direct oral anticoagulants (DOACs) or low molecular weight heparin (LMWH)) are associated with different risks of PTS. We sought to assess the incidence rates of PTS development following a proximal DVT of the lower extremity managed with different types of anticoagulation regimens.

METHODS

A systematic search of MEDLINE, EMBASE and PubMed, from inception to June 2023 was performed. The primary outcome was development of PTS. The secondary outcomes included severe PTS, venous ulcers, and major bleeding. Incidence rates were pooled using the random effects model and expressed as event per 100 patient-years with its associated 95 % confidence intervals (CI) using R software.

RESULTS

A total of 21 (4342 patients) articles were included in the analysis. The adjusted pooled incidence of PTS was 15.1 (95 % CI: 8.7 to 26.1), 18.2 (95 % CI: 9.4 to 35.1) and 24.6 (95 % CI: 9.2 to 65.5) per 100 patient-years patients managed with VKA, DOAC and LMWH, respectively. The adjusted pooled incidence of severe PTS was 5.1 (95 % CI: 2.6 to 10.0) and 0.2 (95 % CI: 0.01 to 2.7) per 100 patient-years for VKAs and DOACs, respectively.

CONCLUSIONS

The development of PTS is common in patients with proximal lower extremity DVT. The incidence rates of PTS seem to be similar across the different anticoagulation regimens, but severe PTS may be lower among patients receiving a DOAC.

Acute phase determinant of post-thrombotic syndrome: A review of the literature

BACKGROUND

Post-thrombotic syndrome (PTS) is the main long-term complication of deep vein thrombosis (DVT). Several therapies are being evaluated to prevent or to treat PTS. Identifying the patients most likely to benefit from these therapies presents a significant challenge.

OBJECTIVES

The objective of this review was to identify risk factors for PTS during the acute phase of DVT.

ELIGIBILITY CRITERIA

We searched the PubMed and Cochrane databases for studies published between January 2000 and January 2021, including randomized clinical trials, meta-analyses, systematic reviews and observational studies.

RESULTS

Risk factors for PTS such as proximal location of DVT, obesity, chronic venous disease, history of DVT are associated with higher risk of PTS. On the initial ultrasound-Doppler, a high thrombotic burden appears to be a predictor of PTS. Among the evaluated biomarkers, some inflammatory markers such as ICAM-1, MMP-1 and MMP-8 appear to be associated with a higher risk of developing PTS. Coagulation disorders are not associated with risk of developing PTS. Role of endothelial biomarkers in predicting PTS has been poorly explored. Lastly, vitamin K antagonist was associated with a higher risk of developing PTS when compared to direct oral anticoagulants and low molecular weight heparin.

CONCLUSIONS

Several risk factors during the acute phase of VTE are associated with an increased risk of developing PTS. There is a high-unmet medical need to identify potential biomarkers for early detection of patients at risk of developing PTS after VTE. Inflammatory and endothelial biomarkers should be explored in larger prospective studies to identify populations that could benefit from new therapies.

Anticoagulation Management Post Pulmonary Embolism

Pulmonary embolus (PE) carries a significant impending morbidity and mortality, especially in intermediate and high-risk patients, and the choice of initial anticoagulation that allows for therapeutic adjustment or manipulation is important. The preferred choice of anticoagulation management includes direct oral anticoagulants. Vitamin K antagonists and low-molecular-weight heparin are preferred in special populations or selected patients such as breastfeeding mothers, those with end-stage renal disease, or obese patients, among others. This article reviews the primary and longer-term considerations for anticoagulation management in patients with PE and highlights special patient populations and risk factor considerations.

Flavonoids as a therapeutical option for the treatment of thrombotic complications associated with COVID-19

The SARS-CoV-2 outbreak has been one of the largest public health crises globally, while thrombotic complications have emerged as an important factor contributing to mortality. Therefore, compounds that regulate the processes involved in thrombosis could represent a dietary strategy to prevent thrombotic complications involved in COVID-19. In August 2022, various databases were consulted using the keywords "flavonoids", "antiplatelet", "anticoagulant", "fibrinolytic", and "nitric oxide". Studies conducted between 2019 and 2022 were chosen. Flavonoids, at concentrations mainly between 2 and 300 μM, are capable of regulating platelet aggregation, blood coagulation, fibrinolysis, and nitric oxide production due to their action on multiple receptors and enzymes. Most of the studies have been carried out through in vitro and in silico models, and limited studies have reported the in vivo and clinical effect of flavonoids. Currently, quercetin has been the only flavonoid evaluated clinically in patients with COVID-19 for its effect on D-dimer levels. Therefore, clinical studies in COVID-19 patients analyzing the effect on platelet, coagulant, fibrinolytic, and nitric oxide parameters are required. In addition, further high-quality studies that consider cytotoxic safety and bioavailability are required to firmly propose flavonoids as a treatment for the thrombotic complications implicated in COVID-19.

Bioactive compounds and functional foods as coadjuvant therapy for thrombosis

Cardiovascular diseases (CVDs) are the leading cause of death. The most common cardiovascular pathologies are thromboembolic diseases. Antithrombotic therapy prevents thrombus formation or dissolves that previously constituted. However, it presents a high rate of accidents such as gastric bleeding and cerebrovascular embolism. Plant foods and their secondary metabolites have been reported to regulate blood hemostasis. This review article aims to propose plant foods and their metabolites as adjuvant therapy for the management of thromboembolic diseases. Various databases were consulted, using antiplatelet, anticoagulant, and fibrinolytic as key terms. In total, 35 foods and 24 secondary metabolites, via in vitro, in vivo, and clinical studies, have been reported to regulate platelet aggregation, blood coagulation, and fibrinolysis. According to the studies presented in this review, plant foods with effects at concentrations less than 50 μg mL^-1 and secondary metabolites with IC₅₀ less than 100 μM can be considered agents with high antithrombotic potential. This review suggests that plant foods and their secondary metabolites should be used to develop foods, ingredients and nutraceuticals with functional properties. The evidence presented in this review shows that plant foods and their bioactive compounds could be used as adjuvants for the treatment and prevention of thrombotic complications. However, further in vivo and clinical trials are required to establish effective and safe doses.

[Risk of post-thrombotic syndrome following direct oral anticoagulant intake: a systematic review and meta-analysis]

OBJECTIVE

To perform a systematic review and meta-analysis of data devoted to the risk of post-thrombotic syndrome (PTS) following direct oral anticoagulant (DOAC) intake.

MATERIAL AND METHODS

A systematic review and meta-analysis of trials available in the PubMed database were performed in March 2021. Analysis included the reports with known Villalta score for PTS in patients receiving DOACs or alternative anticoagulation. We analyzed the incidence and risk of any form of PTS.

RESULTS

We found 10 comparative studies comprising 3161 patients. Incidence of PTS under DOAC therapy was 30.8% (95% confidence interval (CI) 22.2-39.3%), severe PTS - 2.2% (95% CI 1.0-3.4%). DOACs were associated with significantly less risk of any form of PTS (odds ratio (OR) 0.57; 95% CI 0.48-0.68; p<0.001) and severe PTS (OR 0.56; 95% CI 0.36-0.87; p=0.010) compared to vitamin K antagonists. Among various DOACs, specified data were available only for rivaroxaban (OR 0.54, 95% CI 0.42-0.71, p<0.001 for any PTS; OR 0.49, 95% CI 0.27-0.89, p=0.019 for severe PTS). The use of flavonoids in adjunction to rivaroxaban was associated with additional risk reduction for PTS (OR 0.14; 95% CI 0.06-0.31; p<0.001).

CONCLUSION

Moderate quality evidence suggests that DOACs are associated with significant less risk of any PTS and severe PTS compared to VKA in patients with deep vein thrombosis. Among all DOACs, only rivaroxaban has clear data confirming PTS risk reduction. The use of flavonoids in adjunction to rivaroxaban can further improve treatment outcomes.

Oral treatment with a chemically characterized parsley (Petroselinum crispum var. neapolitanum Danert) aqueous extract reduces thrombi formation in rats

Petroselinum crispum var. neapolitanum Danert (Apiaceae) (PC), popularly known as parsley, is an herb native to the Mediterranean region widely cultivated around the world for culinary and ethnomedicinal purposes. The herb is traditionally used in various parts of the world to treat arterial hypertension, hemorrhoid, nose bleeding, hyperlipidemia, and pain, among other indications. The aim of this study was to evaluate the antithrombotic activity of an aqueous extract PC in rats. Aerial parts of a flat-leaf variety of parsley were extracted by decoction. In vivo thrombosis in rat models as well as ex vivo assays were used in the evaluation of PC antithrombotic effects. Intravenous administration of PC (25 mg/kg.b.w), 5 min before thrombosis induction, reduced the venous thrombus formation by 98.2%, while oral administration (125 mg/kg.b.w) impaired it by 76.2%. In the arterial thrombosis model, the oral administration of PC at 15 or 25 mg/kg.b.w, 60 min before thrombosis induction, increased the carotid artery occlusion time by 150% (37.0 ± 6.44 min) and 240% (more than 60 min), respectively. A HPLC-DAD-MS/MS profile of PC extract used in this study was provided. Apiin showed to be the most abundant phenolic compound in the extract. It also revealed the presence of many coumaric acid derivatives. Our results indicate that PC is a potential candidate for the development of a phytotherapeutic drug in the treatment of thromboembolic diseases and provide a detailed chemical profile useful for controlling PC extract production in view of phytotherapy.

Micronized purified flavonoid fraction for the treatment of chronic venous insufficiency, with a focus on postthrombotic syndrome: A narrative review

INTRODUCTION

Postthrombotic syndrome (PTS) is a form of secondary chronic venous insufficiency (CVI) that occurs after deep vein thrombosis (DVT). Effective treatments for PTS are lacking. Micronized purified flavonoid fraction (MPFF) is a venoactive drug used in the treatment of CVI.

OBJECTIVE

To determine whether MPFF is a good candidate to explore as a therapeutic agent for PTS.

METHODS

We performed a narrative review in which we identified 14 systematic reviews, 33 randomized controlled trials, and 19 observational studies that discussed the use of MPFF in CVI, as well as studies that reported on the mechanistic action of MPFF in relation to the pathophysiology of PTS.

RESULTS

MPFF targets a number of pathophysiologic components of PTS. Based on animal models and human studies investigating objective vascular and lymphatic measures, MPFF promotes venous recanalization after DVT, decreases venous remodeling and reflux, inhibits inflammatory processes, improves venous tone and stasis, improves lymphatic circulation, improves capillary hyperpermeability, and decreases tissue hypoxia. Furthermore, MPFF shows promise in improving clinical manifestations, quality of life, and objective venous parameters of CVI. Studies suggest good patient acceptability and tolerability with the use of MPFF in CVI.

CONCLUSION

MPFF is a good candidate to explore as a potential therapy for PTS. Confirmatory high-quality studies are still needed to reinforce the evidence supporting the use of MPFF in CVI. Double-blind randomized controlled trials with clinical endpoints are needed to assess the clinical efficacy of MPFF in the treatment of PTS.