Iliac venous stenting: antithrombotic efficacy of PD0348292, an oral direct Factor Xa inhibitor, compared with antiplatelet agents in pigs

Principles of Optimal Antithrombotic Therapy for Iliac VEnous Stenting (POATIVES): A national expert-based Delphi consensus study

OBJECTIVE

Management of antithrombotic therapy in patients undergoing venous stents has not yet reached consensus, and there are not any recommendations from published guidelines. We undertook a Delphi consensus from Chinese experts to develop recommendations regarding the preferred antithrombotic therapy in patients following venous stenting.

METHODS

The phase 1 questionnaire was comprised of three clinical scenarios of venous stenting for non-thrombotic iliac vein lesions (NIVL), acute deep vein thrombosis (DVT), and post-thrombotic syndrome (PTS) and was sent to venous practitioners across China. In phase 2, the results of phase 1 were distributed to a panel of experts for evaluation along with a questionnaire encompassing a series of statements produced during phase 1. A modified Delphi method was used to reach consensus on recommendations through two rounds of surveys.

RESULTS

The phase 1 questionnaire was completed by 283 respondents. In phase 2, an expert panel consisting of 28 vascular surgeons and interventional radiologists was assembled and voted 17 statements relating to antithrombotic management after venous stenting for NIVL (4 statements), DVT (6 statements), and PTS (7 statements). The majority of the statements about the antithrombotic agent selection received a high consensus strength.

CONCLUSIONS

Based on the national Delphi consensus of Chinese experts regarding antithrombotic therapy following iliac venous stenting in three common scenarios, most of the statements could be used to guide antithrombotic management following venous stenting. Further studies are required to clarify controversial issues including the dose and duration of anticoagulants, the role of antiplatelet agents, especially in patients with NIVL.

Antithrombotic management of patients with deep vein thrombosis and venous stents: an international registry

BACKGROUND

In patients with acute deep vein thrombosis (DVT) treated with catheter-based thrombolysis and venous stenting, poststenting anticoagulant management is uncertain.

OBJECTIVES

To determine the type and duration of antithrombotic therapy used in patients who have received venous stents for treatment of acute lower extremity DVT.

METHODS

We created an international registry of patients with leg DVT from 2005 to 2019 who received venous stents as part of their acute management. We collected data on baseline clinical characteristics and pre-venous and post-venous stent antithrombotic therapy.

RESULTS

We studied 173 patients with venous stents: 101 (58%) were aged ≤50 years, 105 (61%) were female, and 128 (74%) had risk factors for thrombotic disease. DVT was iliofemoral in 150 (87%) patients, and catheter-based treatment was given within 7 days of diagnosis in 92 (53%) patients. After venous stenting, 109 (63%) patients received anticoagulant-only therapy with a direct oral anticoagulant (29%), warfarin (22%), or low-molecular-weight heparin (10%), and 59 (34%) received anticoagulant-antiplatelet therapy. In patients taking anticoagulant-only therapy, 29% received indefinite treatment; in patients on anticoagulant-antiplatelet therapy, 19% received indefinite treatment. Factors associated with combined anticoagulant-antiplatelet therapy vs anticoagulant-only therapy were use of thrombolytic, thrombectomy, and aspiration interventions (odds ratio [OR], 5.11; 95% CI, 1.45-18.05); use of balloon angioplasty (OR, 2.62; 95% CI, 1.20-5.76); and immediate stent restenosis (OR, 7.2; 95% CI, 1.45-5.89).

CONCLUSION

Anticoagulant therapy without concomitant antiplatelet therapy appears to be the most common antithrombotic strategy in patients with DVT and venous stenting. More research is needed to determine outcomes of venous stenting in relation to antithrombotic therapy.

Antithrombotic Therapy after Deep Venous Intervention

Chronic deep venous disease (CVD) can result in significant morbidity and impact on quality of life due to a spectrum of symptoms, including lower extremity edema, venous claudication, and venous ulcers. CVD can be secondary to both thrombotic and nonthrombotic disease processes, including postthrombotic syndrome from prior deep vein thrombosis (DVT) or iliac vein compression syndrome. Endovascular therapy has become a mainstay therapy for CVD patients, with venous stent placement frequently performed. However, the management of anticoagulation following venous stent placement is not well-studied, with no large trials or consensus guidelines establishing an optimal regimen. The current knowledge gap in antithrombotic therapy is magnified by heterogeneity in practice and data collection, along with incomplete reporting in available studies. Furthermore, most published datasets are antiquated in the setting of rapid evolution in technique and technology available for deep venous intervention. Herein, we summarize the current available literature and offer an approach to anticoagulation and antiplatelet management following deep venous intervention for CVD.

Antithrombotic Therapy After Venous Interventions: AJR Expert Panel Narrative Review

Interventions for thrombotic and nonthrombotic venous disorders have increased with technical advances and more trained venous specialists. Antithrombotic therapy is essential to clinical and procedural success; however, post-procedural therapeutic regimens exhibit significant heterogeneity due to limited prospective randomized data as well as incomplete mechanistic understanding of the critical factors driving long-term patency. Post-interventional antithrombotic therapy for thrombotic venous disorders should adhere to existing venous thromboembolism management guidelines, which include 3-6 months of therapeutic anticoagulation at minimum and consideration of extended therapy in patients with higher risk of thrombosis due to procedural or patient factors. The additive benefit of antiplatelet agents in the acute and intermediate period is unknown, having shown improved long-term stent patency in some retrospective studies. Dual and/or triple agent therapy should be limited based on individual risks of thrombosis and bleeding. The treatment of non-thrombotic disorders is more heterogeneous, though patients with limited flow, extensive stent material, or underlying prothrombotic states such as malignancy or chronic inflammation may benefit from single- or multi-agent antithrombotic therapy. However, the agent, dose, and duration of therapy remain indeterminate. Future prospective studies are warranted to improve patient risk stratification and standardize post-procedural antithrombotic therapy in patients receiving venous interventions.

Immediate postprocedure anticoagulation with factor Xa inhibitors of venous stents for nonthrombotic venous lesions does not increase stent patency

BACKGROUND

Many clinicians will prescribe anticoagulation therapy for patients after iliac vein stenting to prevent early or late stent thrombosis. At present, it is unknown whether therapeutic anticoagulation has any effect on stent patency. Thus, we assessed the role of short-term anticoagulation on iliac vein stent patency in patients with nonthrombotic iliac vein lesions (NIVLs).

METHODS

We performed a retrospective medical record review of all iliac vein stents placed for NIVLs at the Center for Vascular Medicine from January 2018 to December 2019. We compared the stent patency in the two groups. The anticoagulation (AC) group had received rivaroxaban or apixaban postoperatively for a minimum of 90 days and were compared with a group that had received no postoperative anticoagulation (NAC). Stent patency was assessed using transabdominal ultrasound at 3, 6, 12, 18, 24, and 30 months. At the discretion of the treating physician, the patients who demonstrated thrombus layering on surveillance ultrasound scanning continued rivaroxaban or apixaban until thrombus resolution was observed. The demographics and stent location, diameter, and length were assessed. Stent patency was analyzed using life table analyses. Differences in stent patency were analyzed using GraphPad Prism, version 8, statistical software (GraphPad Software Inc, La Jolla, Calif) and the log-rank (Mantel-Cox) test.

RESULTS

The number of patients and stents in each group were as follows: AC group, 299 patients and 308 stents; and NAC group, 77 patients and 90 stents. The average age was 52.24 ± 13.44 years and 55.63 ± 14.49 years in the AC and NAC groups, respectively (P ≤ .065). Women constituted 76% of the patients in the AC group and 72% in the NAC group. The average stent diameter and length for the AC group was 20 ± 2 mm and 77 ± 13 mm and for the NAC group was 19 ± 2 mm and 82 ± 9 mm, respectively. The stents had been placed in the right common iliac vein, bilaterally, or left common iliac vein territory in 15%, 3%, and 82% in the AC group and 18%, 2%, and 80% in the NAC group, respectively. The cumulative stent patency at 30 months was 98.7% and 94.6% for the NAC and AC groups, respectively (P ≤ .83). All the stents placed were Wallstents (Boston Scientific, Marlborough, Mass). A total of eight insertion site thromboses occurred that did not affect stent patency: five in the AC group (1.6%) and three in the NAC group (4.5%; P = .15). In addition, 19 patients demonstrated evidence of thrombus layering, with 6 receiving extended anticoagulation.

CONCLUSIONS

Our data indicate that perioperative stent thrombosis in patients with NIVLs is uncommon. Thus, anticoagulation for perioperative stent thrombosis prophylaxis is not necessary. Anticoagulation should only be used for patients with insertion site thromboses and should be considered if thrombus layering is observed on surveillance scanning.

Stent Embolization Mimicking Acute Myocardial Infarction

Venous thromboembolism is associated with significant morbidity and mortality if left untreated. Anticoagulation is the cornerstone of treatment. Venous stents are a relatively newer entity that are increasingly being used to treat venous stenosis/occlusion. It is a safe procedure, but complications include vein rupture, arterial puncture, retroperitoneal bleeding, and in-stent thrombosis. Stent migration is a rare but potentially fatal complication. We present a case of venous stent embolization to the heart that presented as a non-ST segment elevation myocardial infarction.

Antithrombotic Therapy after Venous Stent Placement

Chronic deep venous disease (CVD) affects millions of Americans and can result in significant morbidity, such as debilitating lower extremity oedema, venous claudication, and in severe cases, venous ulcers. CVD can be caused by thrombotic and non-thrombotic disease processes, such as deep venous thrombosis and iliac compression syndrome. Recently, endovascular intervention with percutaneous transluminal angioplasty and venous stent placement has become the mainstay therapy for these patients, with several studies demonstrating its safety and efficacy. However, anticoagulation management following venous stent placement is largely unstudied, and there are no large randomised controlled trials or official guidelines establishing an optimal regimen. Most published studies are plagued with data heterogeneity and incomplete reporting. This is further complicated by rapidly evolving improvements in technique and dedicated devices in endovenous intervention. In this article, the authors discuss the current literature to date and offer an approach to anticoagulation and antiplatelet management following venous stent placement in CVD.

Evaluation of anticoagulant and antiplatelet therapy after iliocaval stenting: Factors associated with stent occlusion

OBJECTIVE

Iliocaval stenting has gained increased use over recent years for a variety of indications, including May-Thurner syndrome (MTS), post-thrombotic syndrome (PTS), and acute deep vein thrombosis (DVT).

METHODS

A retrospective review of 155 patients undergoing iliocaval venous stenting at a large teaching hospital was performed. Clinical and procedural data, mode and duration of anticoagulation or antiplatelet therapy, and outcomes were recorded.

RESULTS

Forty-five patients were treated for MTS, 49 for PTS. and 61 for acute DVT. The median follow-up was 19 months (interquartile range, 9-30 months). Primary patency rates were 97.8% in the MTS group, 85.7% in PTS, and 85.2% for the acute DVT group. Stent restenosis or occlusion occurred in one patient with MTS (2.2%), seven patients with PTS (14%), and nine patients with acute DVT (15%). An ipsilateral DVT recurred in 7 patients with PTS (14%) and 15 patients with acute DVT (25%). The stents that occluded had a tendency toward longer length (162.2 vs 125.2 mm; P = NS) and extension into the common femoral vein (18.8 vs 5.3%; P = NS). The patent stent group had statistically larger nominal diameter stents (P = .013). The duration of anticoagulation did not seem to be a significant factor in stent patency.

CONCLUSIONS

Stent diameter has a significant influence on iliocaval stent patency rates.

Reconstruction of the iliocaval venous confluence using arterial stent technology

Reconstruction of the iliocaval confluence remains a challenge for physicians performing interventions in the deep venous system. We report a case of caval bi-iliac occlusion in which arterial stent technology in the form of the AFX2 unibody stent graft (Endologix, Irvine, Calif) was used to achieve anatomic reconstruction of the iliocaval confluence.

Long-term antithrombotic therapy after venous stent placement

OBJECTIVES

To examine the prescribing patterns and outcomes of antithrombotic regimens after venous stent placement.

METHODS

A total of 87 patients who received inferior vena cava or iliofemoral venous stents were included in the study. A retrospective review was performed to determine the antithrombotic regimens and the subsequent rates of in-stent restenosis, stent thrombosis, and bleeding.

RESULTS

The prescribing patterns of specific antithrombotic regimens were highly variable. In-stent restenosis and stent thrombosis events were observed in 13 of 63 patients (21%) with available follow-up imaging, while major bleeding events were noted in 6 of 87 patients (7%). Triple therapy appeared to reduce the odds of in-stent restenosis/ stent thrombosis when compared to dual antiplatelet therapy (OR = 0.07, P = 0.01).

CONCLUSIONS

Substantial variability exists in antithrombotic therapy following venous stenting at our institution. This study demonstrated a reduction of in-stent restenosis/thrombosis events when utilizing triple therapy compared to antiplatelet-only regimens. However, larger prospective trials are needed to more accurately determine the relative risks and benefits of each antithrombotic regimen.

[A post-thrombotic pelvic congestion syndrome]

INTRODUCTION

Pelvic congestion syndrome is a chronic pelvic pain syndrome related to pelvic varices developed in the setting of primary venous insufficiency or secondary to venous obstruction.

OBSERVATION

We report the case of a 35-year-old patient undergoing anticoagulant therapy for an extensive unprovoked left iliac vein thrombosis, who developed a disabling pelvic congestion syndrome secondary to chronic obstruction of the left iliac vein. Recanalization with stenting of the left iliac vein, combined with antithrombotic treatment with antiplatelet therapy (aspirin 100mg) and anticoagulation (rivaroxaban 20mg) for three months, followed by antiplatelet therapy alone, led to a complete and lasting regression of symptoms.

DISCUSSION

Management of pelvic congestion syndrome secondary to post-thrombotic lesions must take into account its pathophysiology. It involves iliac venous angioplasty with stent placement in combination with antithrombotic therapy, which modalities remain to be specified in long-term follow-up.

Intervention radiology for venous thrombosis: early thrombus removal using invasive methods

The post thrombotic syndrome is one of the most dreaded complications of proximal deep vein thrombosis. This syndrome leads to pain and suffering with leg swelling, recalcitrant ulceration and venous claudication which greatly impairs mobility and quality of life. The prevalence can be high in patients with iliofemoral venous involvement particularly in the setting of a proximal venous stenosis, such as occurs in May Thurner syndrome. Anticoagulation alone does not reduce the likelihood of this outcome. Compression therapy may be effective but garment discomfort limits its implementation. Pharmacomechanical thrombectomy, which combines catheter-directed thrombolysis with mechanical thrombus dissolution, provides an attractive treatment strategy for such patients. The rationale and delivery of pharmacomechanical thrombectomy, including patient selection and adjunctive antithrombotic therapy, will be reviewed in addition to tips and tricks for managing difficult patient scenarios.

Successful sinus restoration for transverse-sigmoid sinus dural arteriovenous fistula complicated by multiple venous sinus occlusions: The usefulness of preoperative computed tomography venography

BACKGROUND

Although sinus restoration for transverse-sigmoid sinus (TSS) dural arteriovenous fistula (DAVF) has rarely been reported over the past decade, its advantage and indication still remain unclear. Herein, we discuss the indications and technical aspects of this therapy with a review of the literature.

CASE DESCRIPTION

A 79-year-old female was referred to our department with generalized convulsion. An angiogram revealed a DAVF at the junction of the right TSS. The right sigmoid and left transverse sinuses were occluded, which resulted in remarkable leptomeningeal venous reflux and cerebral venous congestion. A preoperative computed tomography (CT) venogram precisely revealed the occluded segment of the right sigmoid sinus, which facilitated the sinus restoration with balloon percutaneous transluminal angioplasty and stenting.

CONCLUSION

Sinus restoration is preferable in patients with severe cerebral venous congestion due to multiple sinus occlusions and/or a restricted collateral venous outlet. CT venography is useful for precise evaluation of the length and configuration of the occluded segment, which thus make it possible to evaluate the feasibility of stenting.

Combination of factor Xa inhibition and antiplatelet therapy after stenting in patients with iliofemoral post-thrombotic venous obstruction

OBJECTIVES

Studies addressing optimal postprocedural pharmacological management after endovascular stenting of iliofemoral post-thrombotic venous obstruction are lacking. We report our early clinical experience with a combination of rivaroxaban and clopidogrel in patients after iliofemoral post-thrombotic venous obstruction stenting.

METHODS

Demographic, procedural, and follow-up data of nine patients (seven women; mean age of 32 ± 11 years) undergoing 10 procedures for iliofemoral post-thrombotic venous obstruction performed between August 2012 and January 2014 were retrospectively reviewed. After endovascular intervention, all patients were administered 20 mg rivaroxaban once daily (s.i.d.) and 75 mg clopidogrel s.i.d. or every second day depending on the individual drug responsiveness for at least six months. The adenosine diphosphate-induced platelet aggregation (platelet aggregation, in aggregation units × min) was assessed on a Multiplate analyzer. Patency was verified venographically at procedure end and was evaluated with duplex ultrasound in regular follow-ups.

RESULTS

Iliofemoral venous flow was successfully re-established by percutaneous endovascular angioplasty and stent implantation in nine left-sided and one bilateral iliofemoral post-thrombotic venous obstruction. Under dual treatment strategy of rivaroxaban and clopidogrel with platelet aggregation control (median (range): 285 aggregation units × min (192; 402)), none of the patients experienced restenosis or stent thrombosis, respectively. After a median follow-up of 14 months (range: 6-26 months), the primary patency rate was 100% and no in-stent restenosis, stent occlusion or relevant minor or major bleeding occurred.

CONCLUSION

Combined factor Xa inhibition and tailored antiplatelet therapy after stenting of iliofemoral post-thrombotic venous obstruction were safe and performed favorably in terms of vessel patency.

Latest developments in anticoagulant drug discovery

Thromboembolic diseases have increased in number over the past years. Oral anticoagulants impair the formation and progression of thrombotic processes and are therefore of great importance in the treatment of these diseases. Until recently, vitamin K antagonists were used to block the coagulation system. But these agents display a lot of interactions besides their narrow therapeutic range and have potential risk of hemorrhage complications. Therefore, other factors of the coagulation cascade are currently being explored as therapeutic targets for the development of novel anticoagulants. This review will provide an overview of new drugs promising more effectiveness in the treatment of arterial and venous embolism. Furthermore, pharmacodynamics and drug interactions regarding new anticoagulants will be reported.

Platelet recruitment to venous stent thrombi

Thrombosis following venous stent placement is a morbid clinical outcome. Whether to target platelets or coagulation factors for venous stent thromboprophylaxis remains unclear. We sought to determine whether integrin α(IIb)β3 antagonism with lamifiban would inhibit platelet recruitment to venous stent thrombosis. Anti-thrombotic efficacy was compared between venous and arterial circulations. Pigs received either lamifiban (0.2 mg/kg bolus plus 0.2 mg/kg/h infusion; n = 6) or saline (n = 12). Carotid arteries were crush injured and then harvested 30 min later to provide an assessment of antithrombotic efficacy in the arterial circulation. Iliac venous stents were then deployed and thrombi allowed to propagate for 2 h before harvesting. Platelet deposition was measured by scintillation detection of autologous (111)In-platelets. Venous thrombi were quantified by weight and compared to platelet, Von Willebrand factor (VWF) and fibrinogen content. Arterial platelet deposition (×10(6)/cm(2)) was reduced >80% by lamifiban (398 ± 437) compared to controls (1,540 ± 883; p < 0.005). Lamifiban also reduced venous thrombus platelet deposition (139 ± 88 vs. 281 ± 167) however did not prevent thrombosis. In control animals, venous stent platelet deposition correlated with plasma fibrinogen content (R(2) = 0.29; p = 0.03). Fibrinogen content correlated directly with venous stent platelet deposition (p = 0.03) but not thrombus weight. Neither venous platelet deposition nor thrombus weights varied by VWF content. Platelet recruitment to venous stent thrombi occurs in part through the integrin α(IIb)β3 receptor. Unlike arterial thrombosis, inhibition of this receptor is insufficient to prevent venous stent thrombosis.

Intramural delivery of rapamycin with alphavbeta3-targeted paramagnetic nanoparticles inhibits stenosis after balloon injury

BACKGROUND

Drug eluting stents prevent vascular restenosis but can delay endothelial healing. A rabbit femoral artery model of stenosis formation after vascular injury was used to study the effect of intramural delivery of alpha(v)beta(3)-integrin-targeted rapamycin nanoparticles on vascular stenosis and endothelial healing responses.

METHODS AND RESULTS

Femoral arteries of 48 atherosclerotic rabbits underwent balloon stretch injury and were locally treated with either (1) alpha(v)beta(3)-targeted rapamycin nanoparticles, (2) alpha(v)beta(3)-targeted nanoparticles without rapamycin, (3) nontargeted rapamycin nanoparticles, or (4) saline. Intramural binding of integrin-targeted paramagnetic nanoparticles was confirmed with MR molecular imaging (1.5 T). MR angiograms were indistinguishable between targeted and control arteries at baseline, but 2 weeks later they showed qualitatively less luminal plaque in the targeted rapamycin treated segments compared with contralateral control vessels. In a first cohort of 19 animals (38 vessel segments), microscopic morphometric analysis of the rapamycin-treated segments revealed a 52% decrease in the neointima/media ratio (P<0.05) compared to control. No differences (P>0.05) were observed among balloon injured vessel segments treated with alpha(v)beta(3)-targeted nanoparticles without rapamycin, nontargeted nanoparticles with rapamycin, or saline. In a second cohort of 29 animals, endothelial healing followed a parallel pattern over 4 weeks in the vessels treated with alpha(v)beta(3)-targeted rapamycin nanoparticles and the 3 control groups.

CONCLUSIONS

Local intramural delivery of alpha(v)beta(3)-targeted rapamycin nanoparticles inhibited stenosis without delaying endothelial healing after balloon injury.