Active clinical trials for "Thrombosis"

The main venous thromboembolism (VTE) risk prediction model for ambulatory cancer patients is Khorana. Cancer thrombosis is associated with elevated thrombin generation. Its quantification is a promising method for evaluating patient's thrombotic profile. This study aims to develop a predictive model of VTE risk in ambulatory cancer patients, combining thrombosis biomarkers (D-dimers and thrombin generation potential) with the Khorana score. This is a prospective observational study that includes newly diagnosed cancer patients proposed for anti-tumor treatment (chemotherapy, immunotherapy or targeted therapies). Patients with disease progression are allowed if chemotherapy-free for 3 months. A 6-month mean incidence of VTE 6-10% is expected, requiring a sample size of 600 patients. Blood sample is collected at inclusion to analyze thrombosis biomarkers and blood count. The primary endpoint is the occurrence of symptomatic or incidental VTE within 6 months of inclusion. Models will follow a logistic approach with K-fold cross-validation (k=10). Model quality will be assessed with Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC). Decision for entering predictors in multivariate models will be based on p <.10 in the univariate analysis.

Atrial fibrillation (AF) is the most frequently encountered cardiac arrhythmia. Emerging data suggests that common genetic variants are associated with the development of AF. The main feature of the structural remodelling in AF is atrial fibrosis and is considered the substrate for AF perpetuation. Genome-wide association studies suggest that AF-susceptibility variants may modulate atrial fibrosis. However, the association between atrial fibrosis and genetic polymorphisms in humans has not yet been specifically investigated. In this study, we plan to investigate the relationship between genetic polymorphisms, atrial fibrosis and other components of thrombogenic substrate in patients with non-valvular AF. Primary objectives of this study are to assess associations between (i) polymorphic genetic variants and atrial fibrosis (detected by magnetic resonance imaging), (ii) polymorphic genetic variants and components of thrombogenic substrate (inflammation, endothelial function, prothrombotic state, atrial functions).

In pregnant women with suspected DVT, a sure diagnosis is mandatory. In non-pregnant patients, sequential diagnostic strategies based on 1) the assessment of clinical probability, 2) D-dimer measurement and 3) compression ultrasonography (CUS) have been well validated. Clinical probability assessment by clinical prediction rules (CPRs) is a crucial step in the management of suspected DVT. However, the most commonly used CPR for DVT, the Wells' score, has never been validated in pregnant women. Recently, the 'LEFt' clinical prediction rule was derived and internally validated. A prospective validation of this rule is now warranted, and we plan to use it in our prospective study. The second step used in the diagnostic strategy including non-pregnant patients is D-dimer measurement. The test has been widely validated in non-pregnant patients and, in association with a non-high clinical probability, it allows to safely rule out DVT. As D-dimer level raise steadily during pregnancy, the specificity of the test decreases and it is less useful in pregnant women. Data from the literature clearly suggest that the usual cut-off set a 500 ng/ml would safely rule out DVT in pregnant women [6]. As the usual cut-off has never been prospectively validated in pregnant women with suspected DVT, we would like to use it in our study. Some studies suggested that complete CUS is safe to rule out DVT in pregnant women. However, this test is not always available. Therefore, a strategy in which the association of clinical probability assessment and D-dimer measurement would allow to safely rule out DVT in a significant proportion of patients without performing a complete CUS, would be of great help in everyday clinical practice and would probably be cost-effective. Therefore, we plan a prospective study to assess the safety of a sequential diagnostic strategy based on the assessment of clinical probability with the LEFt rule, D-dimer measurement and complete CUS in pregnant women with suspected DVT.

This prospective observational follow-up study is designed to assess the long-term outcomes after Venous thromboembolism (VTE) and to assess the effect of the new oral anticoagulant (NOAC) rivaroxaban on the prevalence of post-thrombotic syndrome (PTS). The study will not be testing any formal hypothesis.

To clarify the effectiveness and safety of the direct factor Xa inhibitor rivaroxaban in domestic clinical use for patients with deep vein thrombosis and pulmonary embolism

Approximately half a million Americans annually experience venous thromboembolic disease, including deep venous thrombosis (DVT) and pulmonary embolism (PE). Since 2010, four new oral anticoagulants have been approved for marketing in addition to the vitamin K antagonist warfarin. Very limited head-to-head data exists comparing these treatment options, leaving patients, clinicians, and other stakeholders with little guidance for selecting the best strategy that balances recurrence reduction with risk of bleeding. In the DARE Warfarin CER Study, the researchers compare all five currently available oral anticoagulant agents for the extended treatment of DVT and PE, as well as no extended treatment. This study also aims to evaluate whether treatment heterogeneity exists for specific populations, such as older patients or those with renal dysfunction. In a secondary aim, the study will also leverage a database of linked electronic health record-insurance claims to validate diagnosis definitions and account for potential residual confounding by factors unmeasured in claims data. As the patient population includes all Medicare novel anticoagulant users and large numbers of commercially insured and Medicaid patients, the results will likely be transportable to the majority of US patients experiencing a DVT or PE. Pursuant to the objectives of the Patient-Centered Outcomes Research Institute, a study advisory committee consisting of key stakeholders will be actively involved in the study design and dissemination of results.

This is prospective cohort study in pregnant women who present with signs and symptoms of possible deep vein thrombosis (DVT). All patients will have the same method of assessment of their DVT symptoms (the LEFt clinical decision rule will be applied and D-dimer test will be done) to determine if a compression ultrasound is required. All patients will be followed for a period of 3 months.

Rationale: Cardiovascular diseases are important causes of morbidity and mortality in the industrialized world. Clinical studies indicate an important role for the proteins of the contact activation system (coagulation factor XII (FXII), FXI, prekallikrein and high molecular weight kininogen (HMWK)) on the risk of cardiovascular disease. There is substantial evidence from mouse studies that FXII and FXI participate in the formation and stability of thrombi and in vitro studies showed that collagen is able to activate FXII and hereby stimulate thrombin formation and potentiate the formation of platelet-fibrin thrombi. The investigators want to determine the role of the proteins of the contact activation system in platelet mediated thrombus formation in human blood. Objective: The investigators will study the effects of the proteins of the contact activation system on platelet mediated thrombus formation, embolization and degradation on collagen in a perfusion flow model. Study design: Blood will be collected from human volunteers via a venipuncture in the forearm. Each volunteer will donate maximally four times 30 ml of blood over a period of two days. This blood is used in perfusion flow experiments: blood flows over a coverslip covered with collagen in a flow chamber. The investigators will vary several conditions such as the concentration of the proteins and the shear rate. For perfusion flow experiments, the investigators need fresh whole blood because platelets are viable for four hours. After this time, new blood is needed. Study population: For this study the investigators need blood from human volunteers with a coagulation defect in one of the proteins of the contact activation system, e.g. FXII, FXI, prekallikrein or HMWK and controls without any coagulation defects. Main study parameters/endpoints: The investigators main study endpoint is the ex vivo formation of platelet-mediated thrombi on collagen in a perfusion flow model. The investigators hypothesize that thrombi formed from blood of patients deficient in FXII or FXI are less stable than those formed from blood from controls.

Background: During the repair process of deep venous thrombosis, capillary formation is seen from day 18 to day 25. Contrast agent investigation is well known to detect small vessels in arterial disease. We intend to use this method to detect early vascularisation in the thrombus, in order to get more information about the evolution of the thrombosis in vivo. Aims of the study: Investigation of a newly diagnosed occluding venous thrombus with duplexsonography, using contrast agent and compare the degree of vascularization in the same patient after 3 weeks and 3 months. The relative signal intensity difference (baseline to peak) of the time intensity curve (TIC) is measured in defined region of interests (ROI). Comparison of the visibility of revascularisation between color duplexsonography, power mode and contrast agent will be done. Method: Patients with venous thrombosis of the proximal limb veins (femoral or popliteal vein) will be investigated with ultrasound agent in supine position. 5 ml of the contrast agent sulfur hexafluoride is given intravenously into a vein of the dorsal foot. The measurements are done in a defined area, where the thrombus is fully occluding in color Doppler investigation. The regions of interest will be the vessel walls and the centre of the thrombus in cross section view. The signal intensities are measured at baseline and peak (in decibel) in the centre and in the peripheral part of the vein. 20 patients with acute deep venous thrombosis will be included in this pilot study and investigated at baseline, after 3 weeks and 3 months. Previously (before contrast agent application), the veins are investigated with color - and power Doppler to test visibility in comparison to the contrast agent investigation.

Antiplatelet therapy plays a key role in the prevention of complications related to coronary angioplasty and stenting (PCI) including procedure related myocardial damage. Aspirin and clopidogrel are now universally prescribed in patients undergoing these procedures. However, loading and maintenance doses have not been established and variation in individual response is emerging. New tests to assess the effects of these drugs are being developed but have yet to be incorporated into routine clinical practice. We will assess the effects of aspirin and clopidogrel in a consecutive series of patients undergoing angioplasty using new assays which can be carried out at the bedside. We will compare the results with alternative laboratory based tests and look for an association between the results, peri-procedural myocardial necrosis and subsequent cardiovascular events.