Haemostasis is a complex process affected by many factors including both cellular and plasma components. It is a multistep process starting with platelet adhesion to damaged endothelium and ending in clot fibrinolysis. There are several methods available to study different aspects of haemostasis including adhesion, aggregation, coagulation and fibrinolysis. This review describes the different methods, what aspects of haemostasis they measure and their limitations. Methods discussed include methods to study adhesion (e.g. PFA-100, cone and platelet(let) analyzer and perfusion chambers) and aggregation (e.g. Multiplate, VerifyNow and Plateletworks). Furthermore the principles behind viscoelastic haemostatic assays are presented as well as methods that can analyse aspects of haemostasis in plasma or platelet-rich-plasma samples (thrombin generation, overall haemostasis potential and Thrombodynamics Analyzer).
Coagulation; Haemostasis; Platelets; Coagulation assays; Platelet function testing
Behçet’s disease (BD) is a rare vasculitis in sub-Saharan Africa. Vascular thrombosis, especially venous, is common in this condition and also constitutes a basic diagnostic criterion. Its affection of the superior vena cava is rather rare with only a few cases described in the literature.
A 42-year-old male patient was seen at consultation presenting with a pulsatile, warm and slightly painful right latero-cervical swelling extending to the supraclavicular fossa with the presence of collateral venous circulation for three weeks prior to presentation associated with a mild headache. There were oral and genital ulcerations and erythematous skin lesions associated with a history of inflammatory recurrent arthralgia. Chest computed tomo-angiography showed cruoric internal jugular vein thrombosis extending to the superior vena cava with significant venous collateral circulation. The patient was treated with prednisolone (1 mg/kg/day) and colchicine (2 mg/day), as well as anticoagulation with heparin and vitamin K antagonist (Acenocoumarol) with regular INR monitoring. Clinical evolution was favorable during hospitalization, with residual discrete right supraclavicular swelling. There was no bleeding associated with anticoagulants use.
The case stresses the importance of maintaining a high degree of suspicion for Behçet’s disease in all cases of venous thrombosis.
Superior vena cava syndrome; Thrombosis; Behçet; Dakar
Edoxaban is an oral, direct, factor Xa inhibitor approved in Japan for thromboembolic prophylaxis after lower-limb orthopedic surgery (LLOS), but contraindicated in patients with severe renal impairment (SRI; creatinine clearance [CLCR] ≥15 to <30 mL/min).
This open-label study compared the safety of edoxaban 15 mg once daily in Japanese patients with SRI to that of edoxaban 30 mg in patients with mild renal impairment (MiRI; CLCR ≥50 to ≤80 mL/min; N = 30) undergoing LLOS. Patients with CLCR ≥20 to <30 mL/min were randomized to receive edoxaban 15 mg (N = 22) or subcutaneous fondaparinux 1.5 mg once daily (N = 21). All patients with CLCR ≥15 to <20 mL/min received edoxaban 15 mg (N = 7). Treatment was administered for 11 to 14 days.
Major or clinically relevant non-major bleeding occurred in 6.7%, 3.4%, and 5.0% of patients in the MiRI edoxaban 30-mg, SRI edoxaban 15-mg, and SRI fondaparinux groups, respectively; there were no major bleeding events. No thromboembolic events occurred. At all time points assessed, edoxaban plasma concentrations and changes in coagulation biomarkers were similar between the SRI and MiRI groups.
These results suggest edoxaban 15 mg once daily is well tolerated in Japanese patients with SRI undergoing LLOS.
Clinicaltrials.gov Identifier: NCT01857583.
Electronic supplementary material
The online version of this article (doi:10.1186/s12959-014-0034-9) contains supplementary material, which is available to authorized users.
Edoxaban; Renal impairment; Thromboprophylaxis; Orthopedic surgery
Thrombosis is a deadly malfunctioning of the hemostatic system occurring in numerous conditions and states, from surgery and pregnancy to cancer, sepsis and infarction. Despite availability of antithrombotic agents and vast clinical experience justifying their use, thrombosis is still responsible for a lion’s share of mortality and morbidity in the modern world. One of the key reasons behind this is notorious insensitivity of traditional coagulation assays to hypercoagulation and their inability to evaluate thrombotic risks; specific molecular markers are more successful but suffer from numerous disadvantages. A possible solution is proposed by use of global, or integral, assays that aim to mimic and reflect the major physiological aspects of hemostasis process in vitro. Here we review the existing evidence regarding the ability of both established and novel global assays (thrombin generation, thrombelastography, thrombodynamics, flow perfusion chambers) to evaluate thrombotic risk in specific disorders. The biochemical nature of this risk and its detectability by analysis of blood state in principle are also discussed. We conclude that existing global assays have a potential to be an important tool of hypercoagulation diagnostics. However, their lack of standardization currently impedes their application: different assays and different modifications of each assay vary in their sensitivity and specificity for each specific pathology. In addition, it remains to be seen how their sensitivity to hypercoagulation (even when they can reliably detect groups with different risk of thrombosis) can be used for clinical decisions: the risk difference between such groups is statistically significant, but not large.
Global assays of hemostasis; Hypercoagulation; Thrombosis
Ideal conditions for platelet reactivity testing are critical for optimal selection of a P2Y12 inhibitor. Data are inconsistent regarding the impact of high-fat meals on test assessment.
Participants included 12 healthy subjects not taking antiplatelet drugs after a 12-hour fast. After baseline assessment, subjects were given a 600 mg dose of clopidogrel. Four hours later, maximum platelet inhibition was tested in the fasting state by light transmission aggregometry (LTA), VerifyNow P2Y12, vasodilator-stimulated phosphoprotein (VASP), and whole blood aggregometry (WBA). Subjects were then provided a high-fat meal, and platelet function was evaluated two hours later. Change in measured platelet aggregation by LTA was the primary endpoint of the study. The Wilcoxon Rank Sum test was used to compare the change in platelet reactivity between fasting and non-fasting conditions. The Spearman rho (ρ) correlation coefficient was used to evaluate the association between fasting platelet reactivity and the change following a high-fat meal.
No significant change occurred in maximal light transmission, as assessed by LTA with 5 μM ADP (p = 0.15) and with 20 μM ADP (p = 0.07). There was a significant change in the area under the curve with 5 μM ADP (p = 0.03) but not with 20 μM ADP (p = 0.18). Although there was no significant change with the VerifyNow P2Y12 assay (p = 0.16), the change was correlated with the initial fasting value (Spearman’s rho p = 0.008). The VASP assay and WBA varied minimally.
The high-fat meal did not significantly alter platelet function assessment of commonly used platelet function tests. Greater intra-subject variability existed for the optically-dependent compared with non-optically dependent tests.
Clopidogrel; Blood platelets; Platelet function tests; P2Y12 purinoceptor antagonist; Diet; High-fat
Homocysteine is an amino acid that is toxic to vascular endothelial cells, and plasma elevations have been associated with venous thromboembolism. Severe hyperhomocysteinemia (>100 μmol/L) may result from mutations in the genes coding for enzymes in the trans-sulfuration or the folate/vitamin B12-dependent re-methylation pathways. Here, we report the case of a young woman with severe, recurrent thrombo-embolic events associated with severe hyperhomocysteinemia (111 μmol/L). We identified a homozygous mutation in the cystathionine β -synthase gene (p.I278T) and the presence of the Factor V Leiden mutation. Family study shows segregation of elevated homocysteine in heterozygous relatives for the mutation in the cystathionine β -synthase gene. Management consisted of anticoagulation with warfarin and supplementation with folate, vitamin B6 (pyridoxine) and vitamin B12. After twelve years of follow-up, plasma homocysteine levels remain in the moderate range (~20 μmol/L, reference range 8-12 μmol/L) and no further thromboembolic events were identified.
Mild therapeutic hypothermia is considered standard care in the treatment of patients resuscitated from cardiac arrest. With increasingly more frequent concomitant use of platelet-inhibiting drugs, clinicians must be cognizant of the ramifications of hypothermia on platelet function as part of hemostasis. The effects of hypothermia on platelet function have been studied for more than 50 years, but the results are inconsistent and may be related to the circumstances during which hypothermia is achieved. This review summarizes current knowledge of platelet function during hypothermia and the impact on hemostasis.
Platelets; Hypothermia; Coagulation; Hemostasis
Venous thromboembolism (VTE), comprising deep vein thrombosis and pulmonary embolism, is a common condition associated with a significant clinical and economic burden. Anticoagulant therapy is the mainstay of treatment for VTE, having been shown to reduce the risk of death in patients with pulmonary embolism, and recurrence or extension of thrombi in patients with deep vein thrombosis during the initial treatment period. Long-term anticoagulation is indicated in some individuals with VTE, depending on individual risk of VTE recurrence and anticoagulant-related bleeding. Management of VTE in clinical practice is often complex because patients’ characteristics and treatment needs may differ considerably from those encountered in clinical trials. Current guidelines recommend the use of either low molecular weight heparins or fondaparinux overlapping with and followed by a vitamin K antagonist for the initial treatment of VTE, with the vitamin K antagonist continued when long-term anticoagulation is required. These traditional anticoagulants have practical limitations that have led to the development of direct oral anticoagulants that directly target either Factor Xa or thrombin and are administered at a fixed dose without the need for routine coagulation monitoring. This review discusses practical considerations for hospital physicians and haematologists in the management of VTE treatment, including the potential for the direct oral anticoagulants to simplify treatment.
Apixaban; Dabigatran; Disease management; Edoxaban; Rivaroxaban; Venous thromboembolism
In clinical trials new oral anticoagulants (NOAC) have proved to be
as effective as warfarin for thromboprophylaxis in atrial fibrillation. The aim of
this study was to evaluate the efficacy and safety of these drugs in clinical
Methods and results
All patients treated with new oral anticoagulants at Skåne
University hospital and Halland County Hospital Halmstad between 2009 and
September 2013 was identified in the Swedish national quality registry for atrial
fibrillation and anticoagulation (AuriculA). Medical records were reviewed to
identify thromboembolism and major bleeding and compared to a warfarin cohort with
a time in therapeutic range (TTR) of 76%. There were 826 patients, mean age 70.6,
follow up 591 years, with atrial fibrillation treated with NOAC. Dabigatran was
the initial drug in 79% of the cohort. The incidences of ischemic stroke/ TIA and
major bleeding were 1.9 (95% CI; 1.0-3.2) and 2.0 (95% CI; 1.1-3.5) per 100
patient-years respectively. The corresponding incidences for warfarin were 1.5
(95% CI; 1.0-2.2) and 2.5 (95% CI; 1.8-3.3), with no statistical significance
between the groups. Two subdural hematomas occurred 0.4 (95% CI; 0.06-1.1) per 100
patient-years. Mean age of patients with complications was 77.9 (±5.9) and 69.3
(±11.3) for those without (p < 0.001). The discontinuation rate was 6.5% and
1.7% was due to dyspepsia for dabigatran, lower than the RE-LY trial.
This study, largely based on dabigatran shows that treatment is
efficient and safe in everyday clinical practice and not significantly different
compared to a warfarin cohort with tight anticoagulation control.
Electronic supplementary material
The online version of this article (doi:10.1186/s12959-014-0029-6) contains supplementary material, which is available to authorized
Novel oral anticoagulants; Dabigatran; Atrial fibrillation; Thromboembolism; Major bleeding
Venous thromboembolism (VTE) requires urgent diagnosis and treatment to avoid related complications. Clinical presentations of VTE are nonspecific and require definitive confirmation by imaging techniques. A clinical pretest probability (PTP) score system helps predict VTE and reduces the need for costly imaging studies. d-dimer (DD) assay has been used to screen patients for VTE and has shown to be specific for VTE. The combined use of PTP and DD assay may improve exclusion of VTE and safely avoid imaging studies.
Materials and methods
We prospectively used the Wells PTP score and a DD test to evaluate 230 consecutive patients who presented with VTE symptoms. The receiver operating characteristic curve was used to identify a new DD cutoff value, which was applied to VTE diagnosis and compared with the upper limit of locally established reference range for prediction of thrombosis alone and in combination with the clinical PTP score.
We evaluated 118 patients with VTE symptoms fulfilling the inclusion criteria, 64 (54.2%) with clinically suspected deep vein thrombosis (DVT) and 54 (45.8%) with symptoms of pulmonary embolism (PE). The PTP was low in 28 (43.8%) and moderate/high in 36 (56.25%) of the suspected DVT patients, and low in 29 (53.7%) and moderate/high in 25 (46.3%) of the suspected PE patients. Eighteen cases were confirmed by imaging studies: 9 DVT and 9 PE. The agreement between confirmed cases and PTP was significant with PE but not DVT. The negative predictive value for both DVT and PE with current DD cutoff value of <250 μg/L DDU was 100%, whereas with the calculated cutoff the NPV was 88%.
We confirm that PTP score is valuable tool for medical residents to improve the detection accuracy of VTE, especially for PE. The DD cutoff value of 250 μg/L FEU is ideal for excluding most cases of low PTP; however, the calculated cutoff was less specific for the exclusion of VTE.
d-dimer; Clinical probability; Deep vein thrombosis; Pulmonary embolism
Statins may reduce the risk of first and recurrent venous thromboembolism (VTE). No data are available on their potential benefit in patients treated with the oral anticoagulant rivaroxaban.
The EINSTEIN DVT/PE and EINSTEIN Extension studies compared rivaroxaban with standard of care (n=8280) and placebo (n=1188), respectively. The incidences of recurrent VTE and major bleeding per 100 patient-years for exposure (or not) to statins were calculated. A Cox proportional hazards model was constructed, stratified by index event and intended treatment duration, with statin use as a time-dependent variable, for each treatment group (rivaroxaban vs enoxaparin/vitamin K antagonist or placebo) and adjusted for relevant variables.
In EINSTEIN DVT/PE, 1509 (18.3%) patients used statins during the at-risk period, and 6731 (81.7%) did not. Overall, 2.6 recurrent VTEs occurred per 100 patient-years with statin use compared with 3.8 per 100 patient-years without statins (adjusted hazard ratio [HR] 0.76; 95% confidence interval [CI] 0.46–1.25). HRs for recurrent VTE were similar for concomitant use of rivaroxaban-statin and enoxaparin/VKA-statin. Major bleeding events occurred in 3.0 per 100 patient-years with statin use compared with 2.3 per 100 patient-years without statins (adjusted HR 0.77; 95% CI 0.46–1.29). Due to adjustments in the Cox regression model, the direction of this HR is in contrast to the crude comparison. In EINSTEIN Extension, no recurrent VTEs occurred with statin use in the rivaroxaban group compared with 1.6 per 100 patient-years without statins. In the placebo group, 12.2 recurrent VTEs occurred per 100 patient-years with statin use compared with 13.2 per 100 patient-years without (adjusted HR 0.81; 95% CI 0.35–1.86).
The effect of statins in this secondary analysis of the EINSTEIN VTE treatment program is consistent with other studies that suggest a reduced risk of recurrent VTE, but conclusive evidence of this benefit is lacking. Statins are simple to use, inexpensive, very safe and do not cause bleeding. Therefore, the potential effect on reducing recurrent VTE, which is in the range of that of acetylsalicylic acid, deserves evaluation in a large randomized trial.
Trial registration number
ClinicalTrials.gov: EINSTEIN PE, NCT00439777; EINSTEIN DVT, NCT00440193; EINSTEIN Extension, NCT00439725.
Anticoagulant therapy; Rivaroxaban; Statins; Venous thromboembolism
Patients with deep vein thrombosis or pulmonary embolism are recommended to receive anticoagulation for acute treatment and secondary prevention of venous thromboembolism (VTE). Fast-acting direct oral anticoagulants, with or without parenteral heparin, have the potential to replace vitamin K antagonists in this setting. Rivaroxaban, a direct Factor Xa inhibitor, is approved in the European Union and the United States for the single-drug treatment of deep vein thrombosis and pulmonary embolism and the secondary prevention of recurrent VTE in adults. The approved rivaroxaban dose schedule (15 mg twice daily for 3 weeks followed by 20 mg once daily) was derived based on pharmacological data from the clinical development programme to achieve a strong antithrombotic effect in the acute treatment phase and address the need to balance efficacy and bleeding risk for long-term treatment with a once-daily dose in the maintenance phase. Data from dose-ranging studies, pharmacokinetic modelling and randomised phase III trials support the use of this regimen. Other direct oral anticoagulants have also shown favourable efficacy and safety compared with standard treatment, and apixaban (European Union) and dabigatran (European Union and United States) have been approved in this indication. There are practical aspects to rivaroxaban use that must be considered, such as treatment of patients with renal and hepatic impairment, drug–drug interactions, monitoring of effect and management of bleeding. This review discusses the derivation of the VTE treatment regimen for rivaroxaban, summarises the clinical data for rivaroxaban and other direct oral anticoagulants in VTE treatment, and considers the practical aspects of rivaroxaban use in this setting.
Dosing; Pharmacokinetics; Rivaroxaban; Venous thromboembolism treatment
Increasing age and renal impairment are risk factors for venous thrombosis but also for anticoagulant-induced bleeding. In large-scale phase III trials, non-VKA oral anticoagulants (NOACs) were at least as effective and safe for the treatment of acute venous thromboembolism as warfarin. Here, we review the efficacy and safety of dabigatran, rivaroxaban, apixaban and edoxaban in the subgroups of elderly patients (≥75 years) and patients with impaired renal function (creatinine clearance ≤50 ml/min). In all phase III trials, the efficacy of NOACs in the prevention of recurrent VTE was conserved both in the elderly subgroup and in the subgroup with impaired renal function. In a meta-analysis of the pooled results, NOACs reduced VTE recurrence compared with warfarin in elderly patients. In elderly patients and patients with impaired renal function, the safety of NOACs was in line with the results of the overall study.
NOACs may offer an effective, safer and more convenient alternative for VKAs also in the elderly. However, the efficacy/safety profile of NOACs in the aged population needs to be confirmed in real-life.
Venous thromboembolism; Elderly; Renal insufficiency; Novel oral anticoagulants; Non-VKA-acting oral anticoagulants
Warfarin is known for its interaction with many drugs, resulting in undesired treatment outcomes such as bleeding. The study aimed to assess the prevalence of drug-drug interactions and determinants of bleeding among inpatients on warfarin therapy.
A cohort of inpatients on warfarin treatment was prospectively followed from date of admission until discharge. The study was carried out from January to October 2013 in Ayder Referral Hospital, Northern Ethiopia. Patients on warfarin therapy during the study period and willing to participate were included as study subjects. Each concurrent medication was collected and checked for drug-drug interactions using Micromedex® online drug reference. Data were analyzed using statistical software, SPSS for windows version 16. The relationship between bleeding complications and independent variables (age, sex, residence, type and number of co-medications, dose and duration of warfarin treatment, INR value) was assessed using binary logistic regression analysis (Odds ratio, 95% confidence interval).
Of the total 133 patients enrolled in the study, 78 (58.9%) were females. The mean age of the study participants was 40.81 ± 17.6 years. The prevalence of drug-drug interactions was 99.2%. Among these, 65 (49.2%) patients had at least one major while the others had moderate level of drug-drug interaction. Twenty two (16.5%) patients have developed bleeding complications. Increase in international normalized ratio value was found to be strongly associated with risk of bleeding (P value = 0.00; OR = 0.03 (0.00-0.46)).
Drug-drug interactions with warfarin were prevalent in the study hospital. Bleeding complications due to warfarin were also high. Thus, clinicians should be aware of potential interactions and monitor patients’ international normalized ratio closely.
Drug-drug interaction; Warfarin; Bleeding; Ethiopia
Enoxaparin displays fibrinolytic activity through stimulation of endothelial release of tissue plasminogen activator. Moreover, enoxaparin increases the release of tissue factor pathway inhibitor, which inhibits coagulation activity. However, there are only few reports regarding the use of enoxaparin for the treatment of children with thrombosis complicating congenital heart disease. We report the clinical findings from two patients, one child with an A. cerebri media infarction and another with a left ventricular thrombus. In both cases successful thrombolysis was obtained by intravenous administration of enoxaparin. The first patient was a 12-year-old girl with an atrioventricular septal defect, who underwent biventricular repair at the age of 8 months. She presented with right-sided middle cerebral artery infarction. Thrombolysis was contraindicated, because she was beyond the therapeutic window recommended by accepted guidelines. Enoxaparin 2.5 mg/kg/d was administered as a continuous intravenous infusion (CII). The MRI 10 days later revealed a reopened middle cerebral artery and she experienced complete remission of the neurological signs. The second patient was a 16-year-old boy who had tetralogy of Fallot corrected in late infancy. He presented with severe heart failure and a mural thrombus in the left ventricular apex. Enoxaparin was administered and resulted in complete disappearance of the thrombus within a week. According to our experience, CII of enoxaparin was safe and well tolerated without secondary bleeding and resulted in complete dissolution of the thrombi without secondary embolization. Therefore, CII of enoxaparin may be a possible alternative for the treatment of thrombotic complications in children with contraindications against conventional thrombolytic therapy.
Enoxaparin; Low-molecular-weight heparin; Children; Thrombosis
Erythropoietin (Epo) has been shown to improve myocardial function in models of experimental myocardial infarction, but has also been associated with a rise in thromboembolic events. Thus, the aim of this study was to investigate the influence of Epo on platelet activation and coagulation in patients with acute myocardial infarction (AMI).
The study was designed as a substudy of the randomised, double-blind, placebo controlled REVIVAL-3 (REgeneration of VItal Myocardium in ST-Segment EleVation MyocardiAL Infarction by Erythropoietin) study that investigated the effects of recombinant human Epo in AMI. Serial venous blood samples were collected before and after study medication. Circulating prothrombin fragment F1 + 2, FVII, active FVII, beta thromboglobulin (TG) and P-Selectin were measured before and 60 hours after randomization by immunoassay (n = 94). In a randomly selected subgroup platelet aggregation was measured using whole blood aggregometry (Multiplate Analyzer, n = 45).
After 5 days an increase in FVII was observed after Epo as compared to placebo (P = 0.02), yet active FVII and prothrombin fragment F1 + 2 remained unchanged. Moreover, no statistically significant differences in circulating TG or P-selectin were observed between the groups. As an expected response to peri-interventional therapy with clopidogrel and aspirin, platelet aggregation after stimulation with ADP, TRAP, ASPI or collagen decreased 12 hours and 2 days after PCI. However, no difference between the Epo and the placebo group was observed.
After treatment with Epo in patients with AMI a slight increase in circulating FVII after Epo was not associated with an increase in active FVII, prothrombin fragment F1 + 2, TG or P-selectin. Moreover, platelet aggregation was not altered after treatment with Epo as compared to placebo.
ClinicalTrials.gov Identifier: NCT01761435
Platelet activation; Erythropoietin; AMI; PCI
To evaluate the association between angiotensin I-converting enzyme insertion/deletion (ACE I/D) gene polymorphism and retinal vein occlusion (RVO). A total of 80 patients with retinal vein occlusion who was admitted to the Eye Department of Kartal Training and Research Hospital between 2008 and 2011, and 80 subjects were enrolled in this retrospective case–control study. Patients who experienced RVO within one week to six months of study enrolment were included, and those with coronary artery diseases, prior myocardial infarction history and coagulation disturbances were excluded from the study. The diagnosis was made by ophthalmoscopic fundus examination and fluorescein angiography. The ACE gene I/D polymorphism was determined by polymerase chain reaction, and the ACE gene was classified into three types: I/I, I/D and D/D. In multivariate logistic regression analysis, ACE D/D genotype (p = 0.035), diabetes-mellitus (p = 0.019) and hypertension (p = 0.001) were found to be independent predictive factors for RVO. The results of the present study reveal that ACE D/D polymorphism is an independent predictive factor for RVO. However, one cannot definitely conclude that ACE gene polymorphism is a risk factor for retinal vein occlusion.
Retinal vein occlusion; Angiotensin I-converting enzyme; Polymorphism
Venous thromboembolism (VTE), comprising deep vein thrombosis (DVT) and pulmonary embolism, poses a substantial clinical risk, and the incidence of these thrombotic-related diseases remains high. Anticoagulation aims to prevent thrombus extension and reduce the risk of recurrent events, particularly fatal pulmonary embolism. In EINSTEIN DVT, rivaroxaban was non-inferior to enoxaparin/vitamin K antagonists for the reduction of recurrent VTE, with a similar safety profile and a net clinical benefit. EINSTEIN EXT investigated patients receiving long-term treatment in whom there was no clear decision about continuing or stopping anticoagulation; rivaroxaban was superior to placebo in the reduction of recurrent VTE, showing an acceptable benefit–risk balance. Rivaroxaban has the potential to replace standard therapy, usually parenteral low molecular weight heparin overlapping with and followed by a vitamin K antagonist, for the treatment of acute symptomatic DVT and the secondary prevention of VTE. As the use of rivaroxaban for DVT treatment increases in clinical practice, a fundamental understanding of its clinical benefits in everyday patient care is essential. XALIA (XArelto for Long-term and Initial Anticoagulation in venous thromboembolism) is a multicentre, prospective, non-interventional, observational study investigating the effectiveness and safety of a single-drug approach with rivaroxaban compared with standard therapy in patients with DVT. The study cohort will include approximately 4800 patients (≥18 years old) with objectively confirmed acute DVT who will be treated for a period of ≥3 months. The primary outcomes will be the incidence of treatment-emergent adverse events (primarily major bleeding), symptomatic recurrent venous thromboembolic events and all-cause mortality. Secondary outcomes include: major cardiovascular events; patient-reported treatment satisfaction and adherence; healthcare resource utilization; reasons for drug switching or interruption of treatment; and adverse events. XALIA will follow an international cohort of patients in more than 20 European countries, and others including Israel and Canada. The first patient was enrolled in June 2012, with results expected in 2015. It is anticipated that XALIA will provide important information on the treatment of DVT in a heterogeneous, unselected patient population in a real-world setting and provide important supplementary information to that obtained from the EINSTEIN DVT phase III study.
Deep vein thrombosis; Outcomes; Real-world experience; Rivaroxaban
Venous thromboembolic disease (VTE) is associated with high morbi-mortality. Adherence rate to the recommendations of antithrombotic prophylaxis guidelines (ATPG) is suboptimal. The aim of this study was to describe the adequacy of antithrombotic prophylaxis (ATP) in hospitalized patients as the initial stage of a program designed to improve physician adherence to –ATP recommendations in Argentina.
This study was a multicenter, cross-sectional study that included 28 Institutions throughout 5 provinces in Argentina.
1315 patients were included, 729 (55.4%) were hospitalized for medical (clinical) reasons, and 586 (44.6%) for surgical reasons. Adequate ATP was provided to 66.9% of the patients and was more frequent in surgical (71%) compared to clinical (63.6%) subjects (p < 0.001). Inadequate ATP resulted from underuse in 76.6% of the patients. Among clinical, 203 (16%) had increased bleeding risk and mechanical ATP was used infrequently.
The adequacy of ATP was better in low VTE risk clinical and surgical patients and high VTE risk in orthopedic patients. There was worse adequacy in high risk patients (with active neoplasm) and in those with pharmacological ATP contraindications, in which the use of mechanical methods was scarce. The adequacy of ATP was greater at institutions with < 150 beds compared with larger institutions. This is the first multicentric study reporting ATP in Argentina. Understanding local characteristics of medical performance within our territory is the first step in order to develop measures for improving ATP in our environment.
Thrombosis; Thromboprophylaxis; Venous thromboembolic disease; Adequacy; Pulmonary embolism; Deep vein thrombosis
Atrial fibrillation (AF) patients frequently require anticoagulation with vitamin K antagonists (VKAs) to prevent thromboembolic events, but their use increases the risk of hemorrhage. We evaluated time spent in therapeutic range (TTR), proportion of international normalized ratio (INR) measurements in range (PINRR), adverse events in relation to INR, and predictors of INR control in AF patients using VKAs.
We searched MEDLINE, CENTRAL and EMBASE (1990-June 2013) for studies of AF patients receiving adjusted-dose VKAs that reported INR control measures (TTR and PINRR) and/or reported an INR measurement coinciding with thromboembolic or hemorrhagic events. Random-effects meta-analyses and meta-regression were performed.
Ninety-five articles were included. Sixty-eight VKA-treated study groups reported measures of INR control, while 43 studies reported an INR around the time of the adverse event. Patients spent 61% (95% CI, 59–62%), 25% (95% CI, 23–27%) and 14% (95% CI, 13-15%) of their time within, below or above the therapeutic range. PINRR assessments were within, below, and above range 56% (95% CI, 53–59%), 26% (95% CI, 23–29%) and 13% (95% CI, 11-17%) of the time. Patients receiving VKA management in the community spent less TTR than those managed by anticoagulation clinics or in randomized trials. Patients newly receiving VKAs spent less TTR than those with prior VKA use. Patients in Europe/United Kingdom spent more TTR than patients in North America. Fifty-seven percent (95% CI, 50-64%) of thromboembolic events and 42% (95% CI, 35 – 51%) of hemorrhagic events occurred at an INR <2.0 and >3.0, respectively; while 56% (95% CI, 48-64%) of ischemic strokes and 45% of intracranial hemorrhages (95% CI, 29-63%) occurred at INRs <2.0 and >3.0, respectively.
Patients on VKAs for AF frequently have INRs outside the therapeutic range. While, thromboembolic and hemorrhagic events do occur patients with a therapeutic INR; patients with an INR <2.0 make up many of the cases of thromboembolism, while those >3.0 make up many of the cases of hemorrhage. Managing anticoagulation outside of a clinical trial or anticoagulation clinic is associated with poorer INR control, as is, the initiation of therapy in the VKA-naïve. Patients in Europe/UK have better INR control than those in North America.
Vitamin K antagonists; Atrial fibrillation; International normalized ratio; Anticoagulation
Atrial fibrillation (AF) is a common cardiac arrhythmia, and leading cause of ischemic stroke. Despite proven effectiveness, warfarin remains an under-used treatment in atrial fibrillation patients. We sought to study, across three physician specialties, a range of factors that have been argued to have a disproportionate effect on treatment decisions.
Cross-sectional survey of Canadian Family Doctors (FD: n = 500), Geriatricians (G: n = 149), and Internal Medicine specialists (IMS: n = 500). Of these, 1032 physicians were contactable, and 335 completed and usable responses were received. Survey questions and clinical vignettes asked about the frequency with which they see patients with atrial fibrillation, treatment practices, and barriers to the prescription of anticoagulants.
Stated prescribing practices did not significantly differ between physician groups. Falls risk, bleeding risk and poor patient adherence were all highly cited barriers to prescribing warfarin. Fewer geriatricians indicated that history of patient falls would be a reason for not treating with warfarin (G: 47%; FD: 71%; IMS: 72%), and significantly fewer changed reported practice in the presence of falls risk (χ2 (6) = 45.446, p < 0.01). Experience of a patient having a stroke whilst not on warfarin had a significant impact on vignette decisions; physicians who had had patients who experienced a stroke were more likely to prescribe warfarin (χ2 (3) =10.7, p = 0.013).
Barriers to treatment of atrial fibrillation with warfarin affect physician specialties to different extents. Prior experience of a patient suffering a stroke when not prescribed warfarin is positively associated with intention to prescribe warfarin, even in the presence of falls risk.
Low-molecular-weight heparin (LMWH) is frequently recommended for the treatment of pregnancy associated venous thromboembolism (PAVTE). Given that prior reports have suggested a wide variation in dosing of LMWH in pregnancy and the use of anti-Xa monitoring in pregnancy, the principal aim of this survey was to assess current practices for the management of PAVTE.
An electronic survey was conducted. The target sample was members of the North American Society of Obstetric Medicine and Thrombosis Interest Group of Canada.
The final sample consisted of 27/69 hematologists (39.1%), 30/69 internists (43.5%), 8/69 obstetricians (11.6%), and 4/69 from other specialties (5.7%). For the acute treatment of patients pregnant patients with deep vein thrombosis 42/69 (60.8%) preferred LMWH given twice a day 42/69 (60.8%), whereas 25/69 (36.2%) preferred once daily. These results were similar for patients with pulmonary embolism (PE). For long-term treatment more than 70% of the respondents favoured treatment with full doses of LMWH given once a day or twice a day and 16/69 (23.2%) intermediate doses for patients diagnosed with DVT. These results were similar for patients with PE. Fourteen physicians out of 69 (20.3%) did not measure anti-Xa monitoring during acute treatment period and 24/69 (34.8%) never used anti-Xa levels during the long term treatment period. Management during the peri-partum period varied widely according to the time of the diagnosis of PAVTE.
In conclusion, our survey shows wide variation in practice regarding LMWH dosing and anti-Xa monitoring in pregnancy associated VTE and calls for trials comparing different long term strategies using LMWH in patients with PAVTE.
Pregnancy; Thrombosis; Heparin
Deep venous thrombosis (DVT), which is often associated with pulmonary embolism (PE), is a serious complication after total knee arthroplasty (TKA). In the present study, we examined the overall thrombotic and thrombolytic status using Global Thrombosis Test (GTT) in non-anticoagulated blood of patients undergoing TKA to develop the predictable marker for the incidence of DVT.
DVT was diagnosed using doppler ultrasonography a day after the surgery in 31 patients with osteoarthritis (n = 24), rheumatoid arthritis (n = 6) and ankylosing spondylitis (n = 1) by the well-trained operator. We measured overall thrombotic and thrombolytic status using GTT and other biomarkers, which is associated with blood coagulation and fibrinolysis, before and immediately after the surgery.
Newly-generated DVT during the operation was detected in 11 of 31 patients (35.4%) 1 day after TKA. There were no differences in markers of coagulation (PT and APTT), platelet activity (platelet aggregation-induced by ADP and collagen) and fibrinolysis (FDP and D-dimer) between non-DVT and DVT group both before and after the surgery. Both Pre- and Post-operative GTT-occlusion times (OT), an index of platelet reactivity, were tended to be shorter, but not significant, in DVT group compared with non-DVT group. Pre-operative GTT-lysis time (LT), an index of thrombolytic activity, was significantly shorter in DVT group compared with non-DVT group, while there were no differences in post-operative value of this index between DVT group and non-DVT group, suggesting overall thrombolytic activity was enhanced in DVT group before surgery.
Our data suggest that enhancement of pre-operative thrombolytic activity assessed by GTT may be a predictable marker for the incidence of DVT after TKA.
Deep venous thrombosis; Global thrombosis test; Thrombolysis
Platelet inhibitors are commonly used to reduce the risk of atherothrombotic events. The aim of this study was to determine the impact of platelet inhibitors, specifically clopidogrel and aspirin, on clot kinetics, strength, and/or structure during the use of thrombin based gelatin matrices and fibrin sealants.
Blood was collected and heparinized from donors on clopidogrel (and aspirin) and age matched control donors. Blood component analysis, whole blood platelet aggregometry, and activated clotting time (ACT) were used to monitor compliance to therapy and identify any differences between donor groups. Clot kinetics and strength were analyzed using thrombelastography (TEG). Field Emission Scanning Electron Microscopy (FESEM) was used to analyze clot structure.
Blood component profiles were similar for both donor groups. Aggregometry indicated that aggregation response to adenosine diphosphate (ADP) for clopidogrel donors was 12% of that for the controls (p = 0.0021), an expected result of clopidogrel induced platelet inhibition. However, blood from both donor groups had an elevated thrombin induced aggregation response. Heparinization of donor blood resulted in similarly elevated ACTs for both donor groups. TEG results indicated similar clot kinetics and strength between clopidogrel and control donor groups for blood alone and when clotting was induced using thrombin based gelatin matrices and fibrin sealants. FESEM images supported TEG findings in that similar morphologies were observed in ex vivo formed clots from both donor groups when thrombin based gelatin matrices and fibrin sealants were used.
These results suggest that platelet inhibitors do not negatively impact clot kinetics, strength, and structure when clotting is initiated with thrombin based gelatin matrices and fibrin sealants.
Floseal; Tisseel; Clopidogrel; Thrombelastography; Thrombin; Hemostasis