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Patients on anticoagulant treatment are constantly increasing, with an estimated prevalence in Italy of 2% of the total population. The recent spreadout of the COVID-19 pandemic requires a re-organization of Anticoagulation Clinics to prevent person-to-person viral diffusion and continue to offer the highest possible quality of assistance to patients. In this paper, based on the Italian Federation of Anticoagulation Clinics statements, we offer some advice aimed at improving patient care during COVID-19 pandemic, with particular regard to the lockdown and reopening periods. We give practical guidance regarding the following points: (1) re-thinking the AC organization, (2) managing patients on anticoagulants when they become infected by the virus, (3) managing anticoagulation surveillance in non-infected patients during the lockdown period, and (4) organizing the activities during the reopening phases.

Direct oral anticoagulants (DOAC) possess high bioavailability, and their anticoagulant effect is more predictable than that of vitamin K antagonists, hence they do not require routine dose adjustment based on laboratory testing. However, there are circumstances when laboratory testing may be useful, including patients who need to undergo surgery or invasive procedures. Most guidelines state that patients on DOAC may safely undergo surgery/invasive procedures by stopping anticoagulation for a few days before intervention without testing if renal function is within normal limits. This review article discusses the pros and cons of measuring (or not measuring) DOAC levels before surgery/invasive procedures by a multidisciplinary team of experts with different background, including the thrombosis laboratory, clinical thrombosis, internal medicine, cardiology and nephrology. The conclusion is that measuring DOAC with dedicated tests before surgical or invasive procedures is important for patient safety. It provides the best and most direct evidence to rule in (or to rule out) clinically relevant concentrations of residual drugs. Regulatory agencies should urgently approve their use in clinical practice. Hospital administrators should make them available, and clinical laboratories should set up the relative methods and make them available to clinicians.

Background Parenteral anticoagulants and vitamin K antagonists (VKAs) have constituted the cornerstone of venous thromboembolism (VTE) treatment. Meanwhile, direct oral anticoagulants (DOACs) provide physicians with an alternative. The Global Anticoagulant Registry in the FIELD (GARFIELD)-VTE observes real-world treatment practices. Objectives Describe initial anticoagulation (AC) treatment patterns in VTE patients who received parenteral AC, VKAs, and/or DOACs within ±30 days of diagnosis. Methods VTE patients were categorized into parenteral AC only, parenteral AC with transition to VKA, VKA only, parenteral AC with transition to DOAC, and DOAC only. Results A total of 9647 patients were initiated on AC treatment alone. 4781 (49.6%) patients received DOACs ± parenteral ACs; 3187 (33.0%), VKA ± parenteral ACs; and 1679 (17.4%) parenteral ACs alone. Rivaroxaban was the most frequently used DOAC (79.4%). DOACs were more frequently used in North America/Australia (58.1%), Europe (52.2%), and Asia (47.6%) than in Latin America (29.7%) and the Middle East/South Africa (32.5%). In patients with suspected VTE, most received parenteral AC monotherapy (67.7%). Patients with deep vein thrombosis were more likely to receive DOACs alone than those with pulmonary embolism with or without deep vein thrombosis (36.2% vs 25.9%). Active cancer patients received parenteral AC alone (58.9%), with 25.5% receiving DOAC ± parenteral AC and 12.8% parenteral AC and VKA. A total of 46.5% of pregnant patients received parenteral AC monotherapy, 34.0% were treated with VKA ± parenteral AC, and 19.5% received a DOAC (± parenteral AC). Conclusion AC treatment patterns vary by patient population, geographic region and site of VTE. Guidelines for AC therapy are not always adhered to.

Oral anticoagulants (OA) are effective drugs for treating and preventing the formation of blood clots in patients with atrial fibrillation, mechanical heart valves and venous thromboembolism but their therapeutic effect is always counterbalanced by an increased risk of bleeding. Direct oral anticoagulants (DOACs) have brought advantages in the management of many patients, with evidence of a lower risk of intracranial bleeding in comparison to vitamin K antagonists (VKAs). However, due to the increased number of anticoagulated patients worldwide, major and life threatening OA-related bleeding is also increasing, and effective reversal strategies are needed. We reviewed the reversal strategies for both VKAs and DOACs in the light of the latest evidence and recent guidelines, taking into account non-specific methods with fresh frozen plasma (FFP), prothrombin complex concentrate (PCC) or four factor PCC, as well as specific reversal antidotes that are already approved or in approval phase. Most published studies on OA reversal have drawbacks, such as lacking a control arm or data on clinically relevant outcomes, and current guidelines’ recommendations are mainly based on panellists’ judgment. There is an urgent need for well-designed studies in this field. In the meanwhile, to improve the correct use of available resources and patients’ outcomes, we suggest a seven-element bundle for an optimal management of OA-associated major bleeding, including the implementation of fast turnaround time for laboratory tests in emergency, i.e. INR and DOAC plasma levels, and to build up a ‘bleeding team’ that includes experts of hemostasis, lab, trauma, emergency medicine, endoscopy, radiology, and surgery in every hospital.

Background/aims Information on coagulation for cirrhotics on anticoagulants is scanty. We investigated plasma from 23 cirrhotics treated with low-molecular-weight-heparin (LMWH) followed by vitamin K antagonists (VKA). Methods On days 1–4 patients received full-dose LMWH. On day-5 VKA was started and LMWH was terminated when INR therapeutic-interval was reached. Blood was collected at peak and trough during LMWH, LMWH + VKA and VKA. Non-cirrhotics on VKA were included as controls. Results Anti-factor Xa increased from baseline-to-peak during LMWH. During LMWH + VKA was high and reverted to zero during VKA. INR was slightly high at baseline, trough or peak during LMWH and increased to 2.2 during LMWH + VKA or VKA. Mean VKA weekly-doses for cirrhotics and controls were 28.5 mg and 28.6 mg. Protein C decreased upon VKA, but not to the expected extent. Endogenous-thrombin-potential (ETP) decreased from baseline (1436 nM min) to trough (1258 nM min) and peak (700 nM min) during LMWH and was further reduced during LMWH + VKA (395 nM min). Conclusions Target-INR for cirrhotics can be reached by VKA dosages similar to those for non-cirrhotics. ETP reduction parallels the effect of LMWH and/or VKA. Whether these parameters represent the antithrombotic action elicited by these drugs remains to be determined by clinical-trials and laboratory-measurements. ETP, being a global-test reflecting both pro- and anti-coagulants targeted by antithrombotic drugs, seems the candidate for these trials.

Summary Introduction Patients on anticoagulant therapy with vitamin K antagonists (VKA) need frequent INR monitoring. Reliability of point-of-care (POC) devices for measuring INR needs rigorous evaluation, particularly in patient with the antiphospholipid syndrome (APS). The aim of this study was to evaluate the accuracy of the ProTime InRhythm™ System (here called device) for INR measurement in patients with APS on VKA. Methods We compared the device INR vs. the laboratory INR measurement for blood samples from 29 APS-positive and 31 APS-negative patients consecutively enrolled. APS was confirmed by positive serological and/or phospholipid-dependent coagulation tests. Chromogenic factor X assay was used to evaluate anticoagulation. Bland–Altman difference plot for paired INR (POC vs. laboratory) was used to evaluate agreement between the device and the laboratory. The device INR relationship with factor X chromogenic assay was evaluated by orthogonal regression analysis. Results Overall, 97% of the device INR measurements were similar to laboratory INR values with an absolute difference less than 0.4 units. Correlation coefficient for the device INR vs. factor X was −0.69 (P < 0.0001, CI 95% −0.80 to −0.52). Conclusions The ProTime InRhythm System™ is an accurate point-of-care device for measuring INR also in patients with and without APS.

Direct oral anticoagulants (DOACs) do not require dose adjustment based on laboratory testing. However, it might be necessary to measure their plasma concentrations in the following specific situations: 1) before thrombolytic therapy in patients with stroke; 2) before surgery or invasive procedure; 3) in case of adverse events (thrombosis or hemorrhage); 4) when immediate reversal of anticoagulation is needed; 5) in patients with extreme body weight; 6) when administering additional drugs potentially interfering with DOACs; and 7) when overdosage is suspected regardless of concomitant bleeding. Basic coagulation tests, such as prothrombin and activated partial thromboplastin time, should not be used as standalone tests to assess the levels of anticoagulation as they are not specific for DOACs and their results are dependent on the type of reagent used for testing. Plasma DOAC concentrations should be assessed by dedicated tests: dilute thrombin time or ecarin tests (for dabigatran) or anti-factor Xa assays (for anti-factor Xa inhibitors). Dedicated tests should be calibrated against their respective plasma calibrators at certified DOAC concentrations and results should be expressed as ng/ml. Caution should be exerted when interpreting the results of the most common hemostatic parameters such as antithrombin, proteins C and S, lupus anticoagulant, or individual coagulation factors, as they may be strongly affected by the presence of a DOAC. Whenever possible, these parameters should be measured 4 to 5 days after discontinuation of DOAC anticoagulation.

The article Reversal agents for oral anticoagulant-associated major or life-threatening bleeding, written by Marco Moia, Alessandro Squizzato was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 24 August 2019 without open access.

Once chronic anticoagulation has been attained (1–2 weeks after initiation), DOAC reaches the steady-state of anticoagulation, and the prolongations of clotting tests reach the values that are characteristic for each patient. Owing to the large inter-individual variability among treated patients [3], it is useful for clinicians to know these values to correctly interpret results of testing on subsequent occasions (see below).

[This corrects the article DOI: 10.1371/journal.pone.0201476.].

Background & Aims Vitamin K antagonists (VKAs) promote recanalization of portal vein thrombosis (PVT) in patients with cirrhosis. However, the benefit of PVT recanalization might be offset by major and minor bleeding associated with use of anticoagulants. We evaluated harmful and beneficial effects of VKA in patients with PVT and cirrhosis. Methods We performed a retrospective study of 63 consecutive patients with cirrhosis given anticoagulants for the first detection of non-neoplastic PVT from 2003 to 2015 in Italy. We collected data on bleeding events in these patients and compared them with those from patients without cirrhosis with venous thromboembolism (VTE) (n = 160) for up to 4 years. Time in the therapeutic range, based on the international normalized ratio, was used to determine the quality of anticoagulation. We also collected data from 139 patients with cirrhosis who did not receive VKAs (controls), to analyze portal hypertension-related events. We performed survival analyses to determine the effects of VKA in patients with PVT vs controls. Results The group with VTE and the group with PVT were comparable in age, sex, and time in the therapeutic range, but patients with VTE received VKAs for a longer time period (31.1 ± 16.9 mo vs 23.3 ± 16.2 mo; P = .002). The incidence of major or minor bleeding was higher in patients with PVT than patients with VTE (major, 24% vs 7%; P = .012; minor, 29% vs 19%; P = .024). Patients with PVT had a higher rate of major bleeding from the upper-gastrointestinal tract than patients with VTE (P = .019), but there were no significant differences in other types of major bleeding (P = .376). Patients with PVT and controls had the same rate of upper-gastrointestinal bleeding. Complete recanalization in patients with PVT receiving VKA (n = 31) was independently associated with increased portal hypertension–related event-free and transplantation-free survival times. Conclusions In a retrospective analysis of 63 patients with cirrhosis given anticoagulants for PVT, we found VKA use to increase risk of minor bleeding, compared with patients without cirrhosis given VKA. However, this risk is offset by the ability of VKA to increase portal hypertension–related, event-free, and transplantation-free survival of patients with PVT recanalization. Portal hypertension, rather than anticoagulants, could account for the difference in risk of major bleeding between patients with PVT vs patients with VTE.

Objective: A study was undertaken to investigate the in vivo pathogenic role of Toll-like receptor 4 (TLR-4) in the antiphospholipid syndrome (APS) by studying the thrombogenic antiphospholipid (aPL) activity in lipopolysaccharide (LPS) non-responsive (LPS–/–) mice and the association between tlr4 gene polymorphisms and APS in patients. Methods: IgGs from two patients with APS, one with aPL negative systemic lupus erythematosus (SLE) and one with normal human serum (NHS), were evaluated for thrombosis, tissue factor (TF) activity and endothelial cell activation in LPS–/– mice displaying a tlr4 spontaneous mutation vs LPS responsive (LPS+/+) mice. Human tlr4 Asp299Gly and Thr399Ile polymorphisms were evaluated by allele-specific PCR in 110 patients with APS with arterial/venous thrombosis and in 220 controls of the same ethnic origin. Results: IgG-APS produced significantly larger thrombi and more leucocytes (WBC) adhering to endothelial cells in the cremaster muscle microcirculation of LPS+/+ mice than IgG-NHS or aPL negative SLE-IgG. These effects were abrogated after absorption of the anti-β 2 glycoprotein I activity by an affinity column. The two IgG-APS induced significantly smaller thrombi and fewer WBC adhering to endothelial cells in LPS−/− mice than in LPS+/+ mice. IgG-APS induced higher TF activity in carotid artery homogenates of LPS+/+ mice than in LPS−/− mice. The prevalence of Asp299Gly and Thr399Ile tlr4 polymorphisms was significantly lower than in controls. Conclusions: These findings in LPS−/− mice and the reduction in the “protective” polymorphism in patients with APS with thrombosis suggest that TLR-4 is involved in the interaction of aPL with endothelial cells in vivo.

Antiphospholipid syndrome (APS) is an acquired cause of venous thromboembolism (VTE), i.e., deep vein thrombosis and/or pulmonary embolism in patients with systemic lupus erythematosus or other autoimmune diseases, as well as in the general population. Antiphospholipid antibodies (aPLs), particularly lupus anticoagulant, are important thrombotic risks factors [1]. Growing evidence demonstrates that aPLs, particularly antibodies specific for β2 glycoprotein I, are not merely a marker of thrombophilia but are pathogenic, directly contributing to hypercoagulability. Current management of VTE in patients with APS does not substantially differ from that in the general population of patients with VTE and without APS. However, a more problematic monitoring of the anticoagulant treatment, both in the acute and in the long-term management, and the high risk of recurrences makes the treatment of VTE in patients with APS more challenging and deserves some special considerations. The intensity and duration of anticoagulation with vitamin K antagonists (VKA) for longer-term secondary prophylaxis are therefore important issues.

A main goal in clinical management of patients with antiphospholipid syndrome (APS) is to prevent thrombotic recurrences and/or miscarriages. For many decades, the only available oral anticoagulant drugs have been vitamin K antagonists (VKA), which are still the cornerstone of long-term treatment of thromboembolism. However, the limits of VKA treatment are well known: narrow therapeutic window and high patient-to-patient variability of response. Moreover, in some patients with APS a higher international normalized ratio (INR) therapeutic target was suggested, and INR inaccuracy due to antiphospholipid antibodies was reported. Therefore, VKA management in APS patients is frequently cumbersome, requires close INR monitoring and may affect patient’s quality of life. A new class of oral anticoagulant agents has been developed, the Direct Oral Anticoagulants (DOA), which directly inhibit a single enzyme of the coagulation cascade. Compared with VKA, they have more stable pharmacokinetic and pharmacodynamic profiles, little interaction with food or drugs with a predictable anticoagulation effect, they can thus be prescribed in a fixed dose, without requiring frequent laboratory monitoring. The efficacy and safety of DOA has been shown in large phase III clinical trials. Unfortunately, translating these good results to APS patients is not straightforward: currently, at least three randomized controlled clinical trials are ongoing.

Tissue factor pathway inhibitor (TFPI) inhibits tissue factor-induced coagulation. The major part of TFPI is releasable by heparin. We recently found eight patients with thrombosis and low levels of heparin-releasable TFPI in whom we investigated the TFPI gene for mutations. A transition of G to A coding for Valine264Methionine in the heparin-binding domain was found. The Val264Met polymorphism had an allele frequency of 3% in 96 healthy individuals. A silent polymorphism was identified in TFPI exon IV (TC), which does not alter Tyrosine 56. Apart from Val264Met, which was detected in one out of the eight patients, no other mutations in the TFPI gene were found in patients with low heparin-releasable TFPI. Analysis of Val264Met in 317 patients with deep vein thrombosis (DVT) and 292 controls showed no association between Val264Met and DVT. However, a study of total TFPI antigen levels in 122 DVT patients and 126 controls demonstrated an association between TFPI levels and venous thrombosis (P = 0·0001). These results provide evidence for a relationship between venous thrombosis and total TFPI level as a possible risk factor, whereas they do not support a link between DVT and mutations in the nine exons of the TFPI gene.

Duration of anticoagulant treatment and recurrence of venous thromboembolism in patients with and without thrombophilic abnormalities

Most cardiopulmonary diseases share at least one symptom with pulmonary embolism (PE). The aim of this study was to identify the most common acute causes of dyspnea, chest pain, fainting or palpitations, which diagnostic procedures were performed and whether clinicians investigate them appropriately. An Italian multicenter collaboration gathered 17,497 Emergency Department (ED) records of patients admitted from January 2007 to June 2007 in six hospitals. A block random sampling procedure was applied to select 800 hospitalised patients. Results of the overall 17,497 patients were obtained by weighting sampled cases according to the probability of the randomisation block variables in the whole population. The case-mix of enrolled patients was assessed in terms of cardiopulmonary symptoms, and the prevalence of acute disorders. The actual performance of procedures was compared with a measure of their accuracy as expected in the most common clinical presentations. PE occurred in less than 4% of patients with cardiopulmonary symptoms. Acute heart failure, pneumonia and chronic obstructive pulmonary disease exacerbation were the most likely diagnoses in patients with dyspnea. Acute myocardial infarction was present in roughly 10% of patients with chest pain. Atrial fibrillation was the prevalent diagnosis in patients with palpitations. Echocardiography, computed tomographic pulmonary angiography, perfusion lung scan, D-dimer test and B-type natriuretic peptide were performed less than expected from their accuracy. Diagnostic strategies, starting from non-specific symptoms and coping with the eventuality of PE, are likely to benefit from an increased awareness of the examination’s accuracy in discriminating among several competing hypotheses, rather than in testing the single PE suspicion.

New anticoagulant drugs alternative to vitamin K antagonists are currently under clinical evaluation. Patient's preferences should be considered in the development of new therapeutic strategies. Our study aim was to elicit patient preferences, and estimate their willingness to pay for the different treatment options. A Discrete Choice Experiment was administered to patients consecutively attending an anticoagulation clinic, either on stable oral anticoagulant therapy, or during their first visit at the time of starting therapy. Six treatment characteristics were analysed: route and number of medication administrations, frequency of monitoring, risk of some minor bleeding, the amount of attention required for drug/food interactions, requirement for dose adjustment, and out-of-pocket treatment cost. Relationships between patient's preferences and their characteristics were analysed. 255 patients participated (55 % men, with a mean age 64 years; 35. 7 % on stable therapy). A statistically significant importance was attributed to all but two characteristics (the amount of attention required for interaction with other drugs/food and for dose adjustment.) Monthly patient willingness to pay was € 79 for tablets versus injections; € 41 for once-daily versus twice-daily tablets, € 25 for drugs without risk of minor bleeding events and € 20 for once-monthly versus twice-monthly monitoring. Patients on stable therapy considered more important the amount of attention required for drug/food interactions than did the starters. Younger or working patients considered the reduction of monitoring frequency more important than did the older or not working patients (retired, housewives). This study elicited preferences from patients on oral anticoagulant therapy with a simple and well established method, which allows to obtain information warranted for planning optimal healthcare. © 2012 SIMI.

Within-individual biological variation of INR (CV(B)) was assessed in 245 selected stable warfarin-treated patients monitored by three thrombosis centers. Selection criteria were: treatment period of six months or longer before the observation period; at least six consecutive INRs within the therapeutic range of 2.0 - 3.0; interval between consecutive INR measurements of two weeks or longer; no change in warfarin dose; no changes in the patient's circumstances which may influence the INR, such as intercurrent diseases, invasive procedures, starting or stopping drugs interacting with warfarin. The minimum, maximum and mean within-individual coefficient of variation CV(B) of the INR measurements in the 245 selected patients were 0.4%, 14.5%, and 9.0%, respectively Analytical performance goals for the INR measurement (imprecision) could be derived from the mean CV(B). For a therapeutic range of 2.0 - 3.0 with warfarin, the desirable and optimum imprecision of INR determination is

Summary. In this overview we address the three phase III studies that compared new oral anticoagulants (dabigatran, rivaroxaban and apixaban) with warfarin in the setting of stroke prevention in atrial fibrillation. Strengths and weaknesses of the studies were examined in detail through indirect comparison. We analyze and comment the inclusion and exclusion criteria, the characteristics of randomized patients, the primary efficacy and safety end points and side effects. All new oral anticoagulants resulted in being non-inferior to vitamin K antagonists in reducing stroke or systemic embolism in patients with atrial fibrillation. Dabigatran 150 mg and apixaban were superior to vitamin K antagonists. Importantly, new oral anticoagulants significantly reduced hemorrhagic stroke in all three studies. Major differences among new oral anticoagulants include the way they are eliminated and side effects. Both dabigatran and apixaban were tested in low- to moderate-risk patients (mean CHADS2 [Congestive heart failure, Hypertension, Age, Diabetes, Stroke] score = 2.1–2.2) whereas rivaroxaban was tested in high-risk patients (mean CHADS2 score = 3.48) and at variance with dabigatran and apixaban was administered once daily. Apixaban significantly reduced mortality from any cause. The choice of a new oral anticoagulant should take into account these and other differences between the new drugs.

The prevalence of major risk factors for VTE may differ according to age, gender and clinical presentation. We tested this hypothesis in a large Italian VTE population. MASTER is a multicenter registry aimed to prospectively collect information on a large cohort of patients with acute VTE. The presence of major risk factors was captured by an electronic data network in consecutive patients with objectively confirmed acute VTE. We enrolled 2,119 patients (49.8% men) of whom 424 (20%)40 years, 529 (25%) between 41 and 60 years, 943 (44.5%) between 61 and 80 years, and 223 (10.5%)80 years. The prevalence of known risk factors in the four age groups is 63.9, 52.6, 54.6, and 58.3%, respectively (p = 0.002). Immobilization and severe medical disorders are more commonly associated with VTE in patients80 years, trauma is significantly more common in patients40 years than in older patient groups. The prevalence of unprovoked events is the highest in patients 41-60 years, and lowest in patients less than 40 years. After logistic regression analysis, patients with pulmonary embolism are more likely to have known risk factors for VTE than patients with deep vein thrombosis at presentation (p = 0.0021), and women are less likely than men to have an unprovoked VTE (p 0.0001). In conclusion, a substantial proportion of VTE events remain classified as unprovoked. Unprovoked events are more common in middle aged patients, in men, and in patients presenting with deep vein thrombosis.

Summary. Background: Knowledge of independent, baseline risk factors for catheter-related thrombosis (CRT) may help select adult cancer patients who are at high risk to receive thromboprophylaxis. Objectives: We conducted a meta-analysis of individual patient-level data to identify these baseline risk factors. Patients/Methods: MEDLINE, EMBASE, CINAHL, CENTRAL, DARE and the Grey literature databases were searched in all languages from 1995 to 2008. Prospective studies and randomized controlled trials (RCTs) were eligible. Studies were included if original patient-level data were provided by the investigators and if CRT was objectively confirmed with valid imaging. Multivariate logistic regression analysis of 17 prespecified baseline characteristics was conducted. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated. Results: A total sample of 5636 subjects from five RCTs and seven prospective studies was included in the analysis. Among these subjects, 425 CRT events were observed. In multivariate logistic regression, the use of implanted ports as compared with peripherally implanted central venous catheters (PICCs), decreased CRT risk (OR, 0.43; 95% CI, 0.23–0.80), whereas past history of deep vein thrombosis (DVT) (OR, 2.03; 95% CI, 1.05–3.92), subclavian venipuncture insertion technique (OR, 2.16; 95% CI, 1.07–4.34) and improper catheter tip location (OR, 1.92; 95% CI, 1.22–3.02), increased CRT risk. Conclusions: CRT risk is increased with use of PICCs, previous history of DVT, subclavian venipuncture insertion technique and improper positioning of the catheter tip. These factors may be useful for risk stratifying patients to select those for thromboprophylaxis. Prospective studies are needed to validate these findings.

Endothelial cells (EC) were isolated from the umbilical vein of a newborn girl with type I 'platelet low' von Willebrand disease (I vWD) and endothelial localization and release and the ability of subendothelial von Willebrand factor (vWF) to support platelet adhesion were compared with those of normal EC. vWF was detectable by immunofluorescence in Weibel-Palade bodies, but the number of Weibel-Palade bodies positive for vWF was lower than in control EC. Patient EC released into the medium significantly smaller amount of vWF, both constitutively and after their stimulation. The vWF content of the extracellular matrix of patient EC was 38% that of control EC matrix. Platelet adhesion studies were performed under flow conditions with umbilical arteries and EC matrices of cultured EC. Using normal citrated whole blood as perfusate, platelet adhesion was lower in the umbilical artery of the patient (9 +/- 1% v 35 +/- 4% for the control) and in her EC matrix (7 +/- 1% v 21 +/- 2% of control). When patient EC matrix was perfused with vWF-deficient reconstituted blood, adhesion was 17 +/- 3% v 32 +/- 3% for control EC matrix; preincubation of patient EC matrix with 1 U/ml vWF increased the adhesion to 30 +/- 6%. These data establish that low contents of vWF in EC and subendothelium are important characteristics of type I vWD 'platelet low', and that such characteristics correlate with low platelet adhesion to the subendothelium.

Oral anticoagulants and antiplatelets are used in the longterm treatment and prevention of thromboembolic diseases. For more than 50 years, vitamin K antagonists (VKA), i.e. warfarin, acenocoumarol, and phenprocoumon, have been the only available oral anticoagulants. New oral anticoagulant drugs will soon be available: those at a more advanced stage of development are a direct thrombin inhibitor (dabigatran etexilate) and two direct factor Xa inhibitors (rivaroxaban and apixaban). Antiplatelet drugs interfere with some steps in the activation process, including adhesion, release, and/or aggregation. Aspirin and thienopyridines (ticlopidine and clopidogrel) are the currently used drugs, but new molecules are coming. VKA are used in the primary and secondary prevention of venous thromboembolism, in the prophylaxis of cardioembolic events in patients with mechanical or biological prosthetic heart valves, in patients with atrial fibrillation, and in some other ischemic myocardial diseases; antiplatelets are used mainly to prevent and/or to treat myocardial infarction, stroke, and peripheral arterial diseases. Combined anticoagulant‐antiplatelet treatment has been attempted in order to increase the efficacy of the antithrombotic treatment in some clinical conditions. Moreover, one patient already on anticoagulant treatment may develop also the indication for antiplatelet treatment, or vice versa. For both anticoagulants and antiplatelets, the efficacy in treating and preventing thromboembolic diseases cannot be dissociated from an increased risk of bleeding; therefore, the combination of these drugs can be not only more effective, but also more dangerous, and should be considered with caution. Overall, the evidence of benefit of combined treatment is limited, and the increased risk of bleeding is proven. However, combined anticoagulant and antiplatelet treatment is frequently prescribed in clinical practice: an aggressive therapeutic approach seems currently to be more attractive and popular than an evidence-based one. Sometimes it may be difficult to assess

The prognostic value of hemostatic parameters after orthotopic liver transplantation was evaluated in 37 consecutive patients. Six simple hemostatic parameters (prothrombin time, activated partial thromboplastin time, thrombin time, thrombin coagulase time, plasma fibrinogen and platelet count) were obtained for each patient pre-transplantation and daily post-transplantation for at least 8 days. Using the results of these tests, the degree of hemostatic impairment was arbitrarily scored from 0 to 6. Starting from the first day post-transplantation, hemostatic parameters improved progressively, reaching plateau values on day 7 post-transplantation. On day 8 there were significant differences in the activated partial thromboplastin time, prothrombin time, and in the overall hemostatic scores between patients who survived at least 6 months and those who died. Comparing these hemostasis parameters with such liver function tests as AST, ALT and serum bilirubin, univariate analysis showed that activated partial thromboplastin time, coagulation score and AST were significant predictors of 6-month survival, but by multivariate analysis (Cox proportional hazard rate model) only the activated partial thromboplastin time was an independent predictor. Hence, a simple coagulation test is useful for predicting the survival of patients undergoing liver transplantation.

To the Editor: Nonvalvular atrial fibrillation (NVAF) is the most common sustained arrhythmia encountered in clinical practice and is associated with a 5-fold increased risk for stroke [(1)][1]. Moreover, patients with NVAF often suffer from atherosclerotic complications such as acute myocardial

Enoxaparin is the most frequently used low-molecular weight heparin in the world, given in order to prevent venous thromboembolism (VTE) in patients undergoing major orthopaedic surgery (MOS). Fondaparinux is an effective and safe alternative. The aim of our study was to compare the cost-effectiveness of enoxaparin and fondaparinux in the extended thromboprophylaxis of patients undergoing MOS in Italy. A decision-tree model was developed: probabilities of symptomatic events were derived from the published trials; use of resources in Italy was evaluated by means of a questionnaire administered to a panel of experts. Only the direct costs of VTE (acute treatment of events and of complications) were considered. Cost units were derived from the current cost of drugs, and from the Italian National Healthcare tariffs in 2007. Incremental cost-effectiveness ratios were analysed at three time points: 30 days, 1 year and 5 years. The higher cost of fondaparinux was counterbalanced by reduced rates of early DVT, early PE and prophylaxis-related major bleeding. If compared with enoxaparin, after 30 days of extended prophylaxis, fondaparinux is associated with a savings ofeuro48.83 per patient; at the end of the first year, the savings increased toeuro72.13, and after 5 years, the savings areeuro74.36. One-way sensitivity analysis shows that the results are robust to the variation in unit costs for VTE-related care, or in event rates for both treatments. In conclusion, our model shows that, when administered for extended prophylaxis of VTE following MOS, fondaparinux is more effective and cost saving than enoxaparin.

Eight healthy volunteers were given single subcutaneous doses of dermatan sulfate (DS, 100, 200 and 400 mg), heparin (5,000 IU) and placebo in random order. Wash-out between treatments was greater than or equal to 10 days. Serial blood samples were taken before and up to 24 hours after treatment to measure coagulation and fibrinolytic parameters. Thrombin generation was significantly inhibited by DS and heparin as compared to placebo. The effect of DS was dose-dependent. Peak inhibition after 200 mg DS was comparable to that of 5,000 IU heparin, but lasted longer. A small, bordeline significant prolongation of APTT was observed after 400 mg DS and heparin. The changes in PAI and fibrinolytic activities were those of the circadian variation. No changes were seen in the other parameters tested. In conclusion, single s.c. doses of DS (200, or 400 mg) inhibit ex vivo thrombin generation equally or more than 5,000 IU heparin and for a longer time. The effect of both treatments on fibrinolysis is negligible.

Introduction Whether patients with hereditary or acquired thrombophilia have an increased risk for recurrence of venous thromboembolism (deep vein thrombosis and/or pulmonary embolism) is still controversial. The aim of this study was to evaluate the incidence of recurrence of venous thromboembolism in patients with and without thrombophilic abnormalities treated with standardized anticoagulant treatment. Material and methods Database was from a prospective multicenter randomized study aimed at evaluating the long-term clinical benefit of extending to 1 year the 3-month oral anticoagulant treatment after a first episode of idiopathic proximal deep vein thrombosis. The screening for thrombophilia included antithrombin, protein C, protein S deficiencies, resistance to activated protein C and/or factor V R506Q mutation, the mutation 20210GA of the prothrombin gene, hyperhomocysteinemia and antiphospholipid antibodies. The diagnosis of venous thromboembolism recurrence was done by objective tests and adjudicated by a panel unaware of the results of the thrombophilia screening. Results A screening for thrombophilic abnormalities was performed in 195 patients. Twenty of 57 (35.1%) thrombophilic patients experienced a recurrence of venous thromboembolism as compared with 29 of 138 (21.0%) patients without thrombophilia (HR=1.78, 95% CI 1.002–3.140, p =0.046). The difference in VTE recurrence between patients with and without thrombophilia was accounted for by those who received 3 months of oral anticoagulation (HR=3.21, 95% CI 1.349–7.616, p =0.008). No difference between thrombophilic and non-thrombophilic patients was observed in the time interval from the index episode to recurrent venous thromboembolism (29.1±23.9 and 30.6±19.8 months, respectively). Conclusions Thrombophilic abnormalities are associated with an increased risk of venous thromboembolism recurrence. The role of thrombophilia in the long-term management of venous thromboembolism should be addressed in prospective management studies.

Objective Variant alleles of the CYP2C9 gene encoding the cytochrome P450 (CYP) enzyme (2C9*2 [Arg144Cys] and 2C9*3 [Ile359Leu]) are known to increase the anticoagulant effect of warfarin and decrease the mean daily dose required to maintain the international normalized ratio (INR) of the prothrombin time within the target therapeutic range. However, little information is available on the effect of CYP2C9 polymorphisms on dose requirements during the most critical step of anticoagulant therapy, the induction phase. Methods This retrospective study evaluated the dosages given to 125 patients who started therapy with warfarin in a clinical center where physicians used the same approach for dosing and frequency of monitoring. CYP2C9 allelic variants were evaluated by polymerase chain reaction followed by restriction enzyme analysis. Results From the time of the first INR estimate (day 4) until the end of the induction phase (arbitrarily established at day 24), patients with 2C9*2 or 2C9*3 variant alleles required lower mean daily doses than patients carrying only wild-type alleles 2C9*1 (−17% and −40%, P < .0001). They also more frequently had INR values above the upper limit of the target range (3.0) (65% for 2C9*2/− and 66% for 2C9*3/− versus 33% for 2C9*1/*1; P = .006 and .012, respectively). Conclusions The requirement of smaller doses of warfarin in relation to CYP2C9 polymorphisms is already manifest on the fourth day of treatment, at the time of the first INR estimate. CYP2C9 genotyping is as yet not warranted, but frequent INR monitoring with appropriate dose adjustments is recommended during the first 3 weeks of treatment to avoid overanticoagulation and the inherent risk of bleeding in carriers of variant alleles. Clinical Pharmacology & Therapeutics (2004) 75, 198–203; doi: 10.1016/j.clpt.2003.09.015

In this prospective study, we evaluated the predictive value of activated partial thromboplastin time on day 8 post transplantation for event-free survival in patients who had had orthotopic liver transplants; both death and retransplantation within 6 months were the events considered. In a 4-year period, 109 patients had orthotopic liver transplants in our hospital, and 104 were eligible for the study since they survived and were not given new transplants within 8 days. The activated partial thromboplastin time was significantly longer in patients who survived event-free for less than 6 months than in those with longer event-free survivals. Kaplan-Meier curves showed that patients with normal activated partial thromboplastin times were nine times more likely to survive more than 6 months without events than patients with prolonged values. The positive predictive value of activated partial thromboplastin time for event-free survival was 88% and the negative predictive value was 54%, indicating that the test is useful for predicting patient outcome. We suggest that activated partial thromboplastin time be performed on day 8 post transplantation to predict the medium-term event-free survival.

See also Aboud M, Morel-Kopp M-C, Ward C, Coyle L. False-negative or false-positive: laboratory diagnosis of lupus anticoagulant at the time of commencement of anticoagulant. J Thromb Haemost 2010; 8: 2070–3; Aboud M, Morel-Kopp M-C, Ward C, Coyle L. False negative or false positive: laboratory diagnosis of lupus anticoagulant at the time of commencement of anticoagulant: reply to a rebuttal. This issue, pp 1436–7.

Type II C is a subtype of defective antithrombin III deficiency in which there is a molecular defect in the heparin binding site. Usually, heterozygous patients with this defect have little or no thrombotic symptoms. Ischemic stroke has never been described. We report the case of a young woman who had an episode of right-sided hemiparesis. The computed tomographic scan showed an ischemic lesion in the left hemisphere. There were no previous thrombotic episodes in the patient’s history and the sole risk factor for thrombosis was taking of an oral contraceptive. Her family history was mildly positive for thrombosis (superficial thrombophlebitis in two relatives). Laboratory tests showed normal antithrombin III antigen, low heparin cofactor activity and an increased slow-moving peak in crossed-immunoelectrophoresis with heparin. The same pattern was found in 7 of 20 relatives. Thus, a diagnosis of congenital type II C defective antithrombin III was made. This report suggests that young patients with ischemic stroke should be screened for defective antithrombin III.

Arterial and venous thrombosis are the most common manifestations of antiphospholipid syndrome. To investigate whether genetic determinants contribute to their thrombotic risk, we studied the prevalence of the G1691 --> A mutation in the gene coding for factor V, the G20210 --> A mutation in the prothrombin gene and the C677 --> T mutation in the methylenetetrahydrofolate reductase gene in 152 patients with lupus anticoagulants. One hundred and twenty-eight cases (84%) also had increased titres of anticardiolipin antibodies. History of thrombosis was present in 96 patients (63%); 67 suffered from venous thrombosis only, 23 cases had arterial thrombosis only, six patients had both venous and arterial thrombosis. Five patients were heterozygous for the G1691 --> A mutation in the factor V gene (3%). All of them (100%) suffered from venous thrombosis compared with 68 out of the 147 cases without the mutation (46%) (P = 0.0474). The prevalence of the G20210 --> A mutation in the prothrombin gene was evaluated in 145 patients; eight of these patients were heterozygous (5%). Four of these patients (50%) experienced venous thrombosis compared with 65 out of the 137 patients without the mutation (47%) (P = ns). Neither mutation was associated with arterial thrombotic events. No patient carried both mutations. The C677 --> T mutation in the methylenetetrahydrofolate reductase gene was assessed in 83 patients; 15 of them (18%) were homozygous and 37 (44%) were heterozygous. There was no significant association between the status of the mutation and history of venous and arterial thrombosis. No significant correlation was found among the three groups. In conclusion, only the G1691 --> A mutation in the factor V gene was associated with the thrombotic risk of patients with lupus anticoagulants.

To assess the natural history and risk factors for thrombosis in a large cohort of unselected patients with antiphospholipid antibodies.Three hundred sixty consecutive patients (118 males, 242 females, median age 39 years [range 2 to 78]) fulfilling the currently accepted criteria for diagnosis of lupus anticoagulant (LAC) (n = 326) and/or raised immunoglobulin G anticardiolipin antibodies (IgG ACA) (n = 185) were collected from 16 Italian institutions and prospectively observed for a median of 3.9 years (range 0.5 to 5). Main endpoints were the occurrence of arterial or venous thrombosis, the outcome of pregnancies, and any severe complications leading to hospitalization or death.Thirty-four patients developed a thrombotic complication, with a total incidence of 2.5% patient-years. Multivariate logistic regression analysis identified two independent risk factors for thrombotic events: a previous thrombosis (RR 4.9; 95% CI, 1.76 to 13.7; P0.005) and IgG ACA titer above 40 units (RR 3.66; 95% CI, 1.24 to 10.8; P0.01). A total of 28 pregnancies were observed in 25 women and 11 (39%) were abortive. Adverse pregnancy outcomes were significantly more frequent in women with a history of miscarriage or vascular occlusion (9/16, 56%) than in asymptomatic women (2/12, 17%) (P = 0.035). Four patients developed non-Hodgkin's lymphoma during the follow-up. Eighteen patients died. Vascular events and hematological malignancies represented the most frequent causes of death (n = 5 for each).The present study shows that: (a) previous thrombosis and ACA titer40 U are independent predictors of thrombosis; (b) history of miscarriage or vascular disease is significantly associated with adverse pregnancy outcome; (c) hematological malignancies can develop during follow-up in patients with antiphospholipid antibodies.

Abstract 543 Background A recurrence occurs in 15–20% of patients with unprovoked venous thromboembolism (VTE) in the two years after the withdrawal of oral anticoagulant treatment. Extending anticoagulant treatment is effective but associated with increased bleeding risk. We assessed the efficacy and safety of aspirin for the prevention of VTE recurrence after a conventional course of oral anticoagulation. Methods Warfasa was an investigator-initiated double-blind randomized placebo-controlled event-driven study. Patients with a first-ever unprovoked VTE who had completed 6–12 months of oral anticoagulant treatment were randomized to receive aspirin, 100 mg daily, or placebo for at least two years. The primary efficacy outcome was objectively confirmed recurrent symptomatic VTE and VTE-related death. Clinically relevant (major and non-major) bleeding were the main safety outcome. All outcome events were blindly adjudicated by an independent committee. Results A VTE recurrence occurred in 27 of the 205 patients who received aspirin and 42 of the 197 patients who received placebo (6.3% versus 11.0% patient-years; hazard ratio, 0.57, 95% CI 0.35 to 0.93) during the study period (mean 24 months) (Figure A). While on study treatment, 22 and 38 patients who received aspirin or placebo, respectively had a recurrence (5.7% versus 10.7% patient-years; hazard ratio, 0.54, 95% CI 0.32 to 0.91) (mean on-treatment period 22 months) (Figure B). One patient in each treatment group had a major bleeding, with a similar incidence of clinically relevant non-major bleeding. Conclusions Aspirin reduces by about 40% the risk of recurrence in patients with unprovoked VTE without increasing bleeding, when given after a 6–12 month anticoagulant treatment. For its safety, practicality and low cost, aspirin is a valid alternative to oral anticoagulants in the extended treatment of VTE. Disclosures: No relevant conflicts of interest to declare.

Purpose: Symptomatic catheter-related thrombosis (CRT) complicates roughly 5% of central venous catheter insertions in cancer patients. Recent studies have failed to show a reduction in CRT with routine use of pharmacologic thromboprophylaxis in all patients. We conducted a meta-analysis of individual patient-level data to identify independent, baseline risk factors of CRT that may help to select high-risk patients for prophylaxis. Methods: PubMed, EMBASE, CINAHL, CENTRAL, DARE, Grey literature databases were searched in all languages from 1995–2008. Only prospective studies and randomized controlled trials (RCTs) were included. The primary end-point was objectively confirmed symptomatic and asymptomatic CRT. Multivariate logistic regression analysis of 17 prespecified baseline characteristics was conducted. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated. Results: A total sample of 5636 subjects from 5 RCTs and 7 prospective studies was included in the analysis. Among these subjects, 425 CRT events were observed (8%). In multivariate logistic regression, the use of implanted ports as compared with peripherally implanted central venous catheters (PICC), decreased CRT risk (OR = 0.43; 95% CI, 0.23–0.80). Alternatively, past history of deep vein thrombosis (DVT) (OR = 2.03; 95% CI, 1.05–3.92), subclavian venipuncture insertion technique (OR = 2.16; 95% CI, 1.07–4.34), and improper catheter tip location (OR = 1.92; 95% CI, 1.22–3.02), increased CRT risk. Conclusions: CRT risk is increased with using PICC catheters, previous history of DVT, subclavian venipuncture insertion technique and improper positioning of the catheter tip. These factors may be useful for risk stratifying patients to select those for thromboprophylaxis. Prospective studies are needed to validate these findings.

Even though it is generally held that cryoprecipitate and fraction I-O correct the prolonged bleeding time (BT) in patients with von Willebrand disease (VWD), perusal of reported data indicates that the correction is usually short-lasting and often partial. We decided to do a controlled study of the relationship between the multimeric structure of von Willebrand factor (VWF) and the BT in five patients with severe (type III) VWD after infusion of three plasma concentrates ("wet" cryoprecipitate, lyophilized cryoprecipitate, and fraction I-O) given in random order. The dosage of concentrates was tailored from in vitro measurements to achieve post-infusion levels of ristocetin cofactor above the lower normal limit (50 U/dL) for at least 3 hours. The postinfusion BT became transiently normal in only two of five patients treated with wet cryoprecipitate, whereas it remained prolonged in all five patients treated with lyophilized cryoprecipitate or fraction I-O. For all the concentrates, the proportion of large VWF multimers calculated by scanning the electrophoretic gels were the same as those for normal standard plasmas. An intact multimeric structure was recovered in postinfusion plasmas of patients treated with wet cryoprecipitate, whereas there was a postinfusion loss of large multimers after lyophilized cryoprecipitate and fraction I-O. These findings indicate that the attainment of a normal BT is the exception rather than the rule after the infusion of three plasma fractions used in the treatment of severe VWD, and that an intact multimeric structure in concentrates and postinfusion plasmas is necessary but not sufficient to sustain a normal BT.

Patients with uraemia have a defect of primary haemostasis expressed as long skin bleeding times and reduced platelet adhesion to the arterial subendothelium. Transfusion of red cells shortens the bleeding time and stops bleeding symptoms in uraemia. This study investigated whether the efficacy of recombinant human erythropoietin in correcting anaemia and the improvement in haemostasis are correlated. Recombinant human erythropoietin was given to seven consecutive patients with chronic uraemia, a history of bleeding, severe anaemia (haematocrit below 23%), and long bleeding times (above 19 min). The progressive rise in haematocrit induced by increasing doses of recombinant human erythropoietin was paralleled by a pronounced shortening of the bleeding time. Platelet adhesion to the subendothelium of human umbilical arteries, very low before the study, increased greatly in all patients and became normal in six. None of the patients bled during the study period.

A hemorrhagic tendency and anemia are two major complications of uremia. There is a significant negative correlation between BT and hematocrit (Ht) in uremic patients. We studied the efficacy of rHuEpo in correcting both these abnormalities in 10 patients on chronic hemodialysis with severe anemia (basal Hb levels 6.2±0.8 g/dL). Seven patients had BT longer than 10 min., 5 had BT longer than 30 min. rHuEpo was given to the patients 3 times a week at increasing doses, from 24 U/Kg to a maximum of 432 U/Kg, aiming to reach Hb levels ⪖12 g/dL. BT was measured (with the template-like disposable device Simplate II) before starting rHuEpo therapy and after reaching the target Hb values. One patient (n° 6) was excluded from the study after 5 weeks of rHuEpo treatment because of development of an arterio-venous fistula thrombosis. The data are shown in the table.Eight of the 9 patients who concluded the study had final BT shorter than 10 min. This demonstrates the efficacy of rHuEpo in correcting both anemia and prolonged BT in uremic patients.

Twelve infusions of plasma concentrates of von Willebrand factor (vWF) were given to four patients with severe (type III) von Willebrand disease (vWD). Their prolonged bleeding times were either completely or partially corrected after five infusions and had not changed after the remaining seven. In contrast, the low platelet coverage of the subendothelial surface of rabbit aorta perfused with normal washed platelets and red cells resuspended in preinfusion patient plasma was completely or partially corrected in ten instances by replacing preinfusion plasma with postinfusion plasma and remained unchanged in two. Postinfusion improvement in surface coverage was greater than that in bleeding time, suggesting that vWF from normal platelets is needed to support optimal platelet-vessel wall interactions in vWD. This possibility was further explored through other perfusion experiments. The subendothelial surface covered by platelets from an untreated patient with type III vWD (containing no measurable vWF) or from a type IIA vWD patient (containing dysfunctional vWF) resuspended in normal plasma was much smaller than that covered by normal platelets resuspended in normal plasma. These results establish that platelet vWF is important in supporting platelet-vessel wall interactions in vWD and also provide experimental support in favour of the therapeutic transfusion of normal platelets in addition to vWF concentrates to correct the bleeding time in vWD patients.