Thrombosis Research - Articles in Press

Automated APTT cycle for the rapid identification of plasma prekallikrein deficiency - Corrected Proof

2010-03-08

Very prolonged activated partial thromboplastin time (APTT) is a challenging issue for coagulation laboratories and warrants further investigation, once preanalytical or analytical causes have been excluded. Abnormal APTT may be due to anticoagulation therapy, primarily heparin, which can be present in the specimen as a therapeutic or contaminant agent, or it may be due to a coagulation factor deficiency, either congenital or acquired (e.g., presence of specific inhibitors directed against single coagulation factors or non-specific inhibitors, such as Lupus Anticoagulants). When haemophilia (A, B or C) and lupus anticoagulants (LAs) have been ruled out, abnormalities in the so-called contact system, which includes plasma prekallikrein, factor XII (FXII) and high molecular weight kininogen (HK), should be investigated. Prekallikrein, also known as Fletcher Factor, is converted to its active form (kallikrein) by FXII that can autoactivate on negatively charged artificial surfaces or in the presence of various biological substances . Plasma kallikrein in turn further activates FXII with consequent amplification of the process. Prekallikrein may also be activated by the serine protease prolylcarboxypeptidase and by heat shock protein 90 in a FXII-independent way. Deficiency of prekallikrein, which is not generally associated with bleeding tendency and is inherited as an autosomal recessive trait , is characterised by severely prolonged APTT that progressively shorten and even normalise when the preincubation time of plasma with the reagent containing a contact activator is extended to at least 10-20minutes . This behaviour is due to a bypass mechanism that allows that sufficient activated FXII is generated to further activate the coagulation factor XI . Shortening of prolonged APTT with extended incubation time of plasma with a contact activator before recalcification was described in LA samples but, in this case, did not achieve normalisation . APTT assays with extended incubation times are not commonly available on automated coagulometers; furthermore, the manual tilt-tube method is not feasible in all laboratories.

History of rFVIIa therapy - Corrected Proof

Ulla Hedner — 2010-03-02

Abstract: Hemophilia patients with inhibitors against FVIII/FIX present with a major challenge in the clinical practice. In the 1970s such patients were treated in association with emergency situations and essential surgery using huge amounts of FVIII/FIX concentrates often preceded by extracorporal adsorption of antibodies against FVIII/FIX. However, moderate to mild bleedings were not effectively treated. A certain hemostatic effect of activated prothrombin complex concentrates (aPCC) not exceeding 65% was reported. Unfortunately, also thromboembolic events occurred, which made them less attractive to use in inhibitor patients. In a dog model the thrombogenic effects on the coagulation system was almost completely avoided by adding antithrombin and heparin, suggesting factors like IXa, Xa or XIa to be responsible. On the other hand FVIIa is not readily inactivated by antithrombin in the circulation. Furthermore, a detailed literature review revealed very high levels of FVII in the aPCC used with some success in the treatment of hemophilia patients with inhibitors. The potential possibility to use FVIIa as a hemostatic agent was investigated by the administration of pure human FVIIa to two hemophilia patients with inhibitors. In both, a hemostatic effect was recorded. The development of recombinant FVIIa was initiated by Novo Nordisk A/S, Denmark, in June 1986 resulting in NovoSeven (rFVIIa) being licensed for use in patients with inhibitors against coagulation factors in EU in 1996. By then, a hemostatic effect of rFVIIa also in non-hemophilia patients such as patients with platelet dysfunctions or suffering from profuse, heavy bleedings initiated by extensive surgery or trauma had been demonstrated. In parallel the mechanism of action of pharmacological doses of rFVIIa was investigated resulting in a revision of the hemostatic process in stressing the compartmentalization of the process to TF-bearing cells and to thrombin activated platelets at the site of injury. The initial thrombin generation is generated by the formation of the TF-FVIIa-complex formed initially on the TF-bearing cells.

Analysis of tissue factor positive microparticles - Corrected Proof

Nigel S. Key — 2010-03-02

Abstract: There has recently been intense interest in the clinical measurement of tissue factor (TF)-positive microparticles (MPs) in clinical disease states. This interest has been driven by the demonstration of an putative role for circulating TF-positive MPs in animal models of thrombus propagation. Both immunological and functional assays for MP-TF have been described. While each approach has its own advantages and drawbacks, neither has yet been truly established as the ‘gold standard’. Heterogeneity of TF-bearing MPs, such as the variable co-expression of surface phosphatidylserine, may determine not only their procoagulant potential, but also additional properties including rate of clearance from the circulation.

Clinical biological remission induced by rituximab in acute refractory chronic relapsing TTP - Corrected Proof

2010-03-02

Thrombotic thrombocytopenic purpura (TTP) is a rare but often fatal disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia and microvascular thrombosis. These symptoms relate to the presence of von Willebrand factor (vWF)-rich platelet thrombi secondary to a congenital or acquired deficiency of ADAMTS13, a vWF-cleaving protease . Acquired forms are usually associated with the presence of anti-ADAMTS13 IgG that in most cases neutralize the enzyme's activity , though non-neutralizing antibodies have also been reported . Prognosis of TTP has been dramatically improved by prompt therapeutic plasma exchange (PE) . However, some acute severe forms are refractory to this treatment and 20-50% of patients develop a chronic, relapsing form needing further alternative treatments. In the last few years rituximab, a humanized anti-CD20 monoclonal antibody, has been proposed both as rescue therapy in acute forms of TTP refractory to PE and prophylactic treatment in relapsing patients who maintain a high anti-ADAMTS13 inhibiting antibody titre even when in clinical remission . In this retrospective report, we describe the clinical course of four idiopathic TTP patients treated with rituximab. Three patients were treated during their first PE-refractory episode, while the fourth was prophylactically treated during remission after his first relapse. ADAMTS13 activity and anti-ADAMTS13 IgG autoantibodies were assessed before and during rituximab treatment.

Platelet binding and activity of recombinant factor VIIa - Corrected Proof

Maureane Hoffman, Dougald M. Monroe — 2010-02-26

Abstract: Recombinant FVIIa was developed for the purpose of treating hemophiliacs with antibody inhibitors. It was initially assumed to act by enhancing factor X activation by a tissue factor-dependent mechanism. However, the very high levels of FVIIa required for hemostatic effect in vivo seemed inconsistent with this mechanism. After many years of debate, in now appears that platelet surface binding and activity play an important role in the efficacy of FVIIa as a bypassing agent in hemophilia. Platelet binding was initially suggested to be mediated by binding to anionic phospholipid exposed on platelet surfaces upon activation. It now appears that the glycoprotein Ib/IX/V complex also plays a role in FVIIa binding to platelets. However, the characteristics of FVIIa binding to GPIb/IX/V to not seem to fully explain platelet localization of FVIIa to platelets. Thus, there are still unanswered questions in fully understanding the mechanism of hemostatic action of recombinant FVIIa.

Interdependent biological systems, multi-functional molecules: The evolving role of tissue factor pathway inhibitor beyond anti-coagulation - Corrected Proof

Eric W. Holroyd, Robert D. Simari — 2010-02-25

Abstract: Coagulation, innate immunity, angiogenesis, and lipid metabolism represent fundamental and interdependent biological systems. While tissue factor pathway inhibitor (TFPI) is the major physiological inhibitor of TF, its unique structure and endothelial expression allow multi-modal interactions with constituent molecules in each of these systems. We review emerging data describing roles for TFPI beyond simply opposing the action of TF, particularly with regard to the highly basic c-terminus of TFPI, and highlight potentially exciting new areas for future research.

Cellular sources of tissue factor in endotoxemia and sepsis - Corrected Proof

Rafal Pawlinski, Nigel Mackman — 2010-02-25

Abstract: Sepsis is a systemic host response to infection by pathogenic microorganisms. Activation of the coagulation cascade during endotoxemia and sepsis leads to disseminated intravascular coagulation. This review focuses on tissue factor expression by hematopoietic and non-hematopoietic cells and its contribution to the activation of coagulation during endotoxemia and sepsis.

Analysis three abnormal Protein S genes in a patient with pulmonary embolism - Corrected Proof

2010-02-25

Abstract: A protein S (PS) abnormality is a hereditary risk factor for thromboembolism. A 33-year-old female had a left deep vein thrombosis (DVT) and mild pulmonary embolism (PE). Her PS antigen level was 34.7% and the activity level was less than 10%. Genetic analysis identified three missense mutations in PS: the D38Y mutation in exon 3, and the T589I mutation and P626L mutations in exon 15. The D38Y mutation has not been reported previously. An analysis of the patient's family revealed that all members of the family had some PS gene mutation. The D38Y and T589I mutations were both in same allele, the P626L mutation was in another allele. The expression of PS mutations in COS-7 cells revealed that PS activity and antigen were markedly decreased in the D38Y mutation but not in the T589I mutation. The expression of the P626L mutation in baby hamster kidney (BHK) cells showed the PS activity and antigen to be markedly decreased in comparison to the wild type.

Circulating hepatocyte growth factor as an independent prognostic factor of disseminated intravascular coagulation - Corrected Proof

2010-02-25

Abstract: Background: Hepatocyte growth factor (HGF), a pleiotropic factor regulating development and wound healing, is secreted as inactive pro-HGF and is converted into active HGF by coagulation serine proteases. HGF receptor overexpression can cause massive venous thrombi, and factor Xa is reported to release soluble HGF from granulocytes. We hypothesized that a hypercoagulable condition, such as disseminated intravascular coagulation (DIC), may increase circulating HGF through active cleavage by coagulation serine proteases.Methods: In 172 DIC-suspected patients, plasma levels of total and active HGF, thrombin-antithrombin complex (TAT), plasmin-antiplasmin complex (PAP), and interleukin (IL)-6 were measured by ELISA. Active HGF release in granulocytes was examined in patients with and without overt-DIC. HGF-induced tissue factor expression in peripheral monocytes was measured by flow cytometry.Results: Circulating levels of total and active HGF correlated well with coagulopathy severity, including DIC score, D-dimer, TAT and PAP levels. HGF positively correlated with IL-6 and absolute neutrophil count. In contrast to the cancer group, HGF levels were significantly increased in accordance with increased DIC scores in non-cancer group. Elevated circulating HGF was an independent prognostic marker in the non-cancer group, while HGF level failed to predict mortality in the cancer group. Amounts of HGF released from stimulated granulocytes were not significantly different between overt-DIC and no overt-DIC patients. HGF potentiated endotoxin-induced tissue factor expression of monocytes in vitro.Conclusion: These findings suggest that circulating HGF is a potential laboratory marker reflecting coagulation activity and DIC prognosis in non-cancer patients and that HGF may play a role in a vicious cycle of hypercoagulability.

Heparin versus prostacyclin in continuous hemodiafiltration for acute renal failure: Effects on platelet function in the systemic circulation and across the filter - Corrected Proof

2010-02-25

Abstract: Continuous venovenous hemodiafiltration (CVVHDF) is the treatment of choice for critically-ill patients suffering from acute renal failure (ARF). One major problem of extracorporeal circuits is their thrombogenicity, which requires pharmacological blockade of primary (platelet-dependent) or secondary (plasmatic) haemostasis, increasing the patient's bleeding risk.Our study assessed platelet function during CVVHDF, comparing anticoagulant versus antiplatelet pharmacological strategies, commonly used to avoid circuit clotting. Twenty-three critically-ill patients with ARF, requiring CVVHDF were randomized to a prostacyclin analogue (PGI) or to unfractionated heparin (UFH). Ex vivo platelet function, assessed by optical aggregometry (OPA) induced by collagen or ADP, was studied in peripheral blood at baseline, 4 and 24hrs after starting CVVHDF, and at 4hrs within the circuit, before and after the filter (n=9). Coagulation was also monitored.PGI significantly inhibited ADP-induced OPA of peripheral platelets: maximal aggregation (Tmax) was reduced at 4 and 24hrs by 20%, while collagen-induced Tmax was significantly reduced at 4hrs only. In the UFH group, collagen-induced OPA in peripheral platelets was significantly inhibited: slopes of OPA tracings were decreased by 25%, lag time was prolonged by 22%, Tmax decreased by 10% already at 4hrs. ADP-induced OPA showed a similar, but non-significant trend. UFH expectedly prolonged aPTT. In the UFH group, platelet responsiveness to collagen was significantly increased by 30% in post-filter versus pre-filter samples. This effect was blunted in the PGI group.UFH does not protect platelets from filter-induced activation and is associated with a reduced function of systemic platelets. Platelet-inhibiting agents might better prevent the activatory effect of the filter.

Comparison of monitoring methods for lepirudin: Impact of warfarin and lupus anticoagulant - Corrected Proof

Birgitta Salmela, Lotta Joutsi-Korhonen, Ellen Saarela, Riitta Lassila — 2010-02-25

Abstract: Introduction: Appropriate monitoring methods are needed for lepirudin, a direct thrombin inhibitor, as activated partial thromboplastin time (APTT) may under- or overestimate lepirudin. We compared APTT with thrombin-specific methods, also in the presence of warfarin and lupus anticoagulant (LA).Materials and Methods: Lepirudin i.v. was assessed in five patients (35 samples) and in vitro spiked plasma pools: normal control and plasma containing warfarin and LA. Wide dose-responses to lepirudin (0–4.0µg/ml) were studied with APTT (Actin FSL®), Ecarin Chromogenic Assay (ECA®), chromogenic Anti-Factor IIa (Anti-FIIa, Hirudin Activity Assay®), Prothrombinase-induced Clotting Time (PiCT®), and plasma diluted Thrombin Time (dTT).Results: APTT both under- and overestimated in vivo lepirudin doses according to ECA® and Anti-FIIa, which matched completely in various plasma pools at all lepirudin doses (r=0.99). APTT and PiCT® underestimated high lepirudin concentrations in normal plasma, and in LA-positive plasma they were invalid. In all plasma pools, dTT (1:16) indicated lepirudin well up to 1.0μg/ml.Conclusions: ECA® or Anti-FIIa are preferable for lepirudin monitoring, because neither warfarin nor LA, interfered with them, and they were the most precise methods even for supratherapeutic doses. PiCT® reflected co-inhibition of FIIa and FXa, but was disturbed, like APTT, by LA and high lepirudin. Further experience of laboratory monitoring is valuable in this era of new anticoagulants.

Clinical characteristics and laboratory testing of patients with suspected HIT: A survey on current practice in 11 university hospitals in France - Corrected Proof

2010-02-24

Abstract: Summary: We undertook a survey of French university hospital hematological laboratories to ascertain the clinical characteristics of patients with suspected HIT, the laboratory tests performed, and the therapeutic strategy adopted in current practice.Methods: A standardized medical records database for patients with suspected HIT was sent to 19 laboratories. During two months, all consecutive patients for whom a biological test was performed were included.Results: 169 patients were included, 27 (16%) patients having a final diagnosis of HIT. At the time HIT was suspected, the heparin duration and the level of thrombocytopenia were similar in HIT- positive and HIT-negative groups. The use of unfractionated heparin, a therapeutic heparin dose regimen and the presence of thrombotic complications were significantly more frequent in HIT-positive patients. When the heparin dose regimen was taken into account, only thrombotic complications under a therapeutic dose regimen were significantly increased in HIT-positive patients. Eighty-six percent of patients presented at least one alternative diagnosis of thrombocytopenia without significant difference between the two groups. Laboratory tests were performed after a mean of 0.3days and mainly consisted of antigen assays. At the time HIT was suspected, heparin was stopped in 56 (33%) patients, being replaced mainly by danaparoid. Only three laboratories declared they usually received all the necessary clinical information to establish the likelihood of HIT.Conclusion: In current practice in France, the clinical probability of HIT is rarely established, leading to systematic requests for laboratory HIT tests.

WITHDRAWN: Counselling women about hormonal therapy - Corrected Proof

Ida Martinelli — 2010-02-22

The Publisher regrets that this article is an accidental duplication of an article that has already been published in a supplement entitled ‘3rd International Symposium on Women’s Health Issues in Thrombosis and Haemostasis’. The duplicate article has therefore been withdrawn.

WITHDRAWN: Activation of maternal platelets impairs placental function - Corrected Proof

Berend Isermann, Muhammed Kashif, Peter P. Nawroth — 2010-02-22

Swirling flow created in a glass tube suppressed platelet adhesion to the surface of the tube: Its implication in the design of small-caliber arterial grafts - Corrected Proof

Fan Zhan, Yubo Fan, Xiaoyan Deng — 2010-02-22

Abstract: To test the hypothesis that intentionally inducing swirling blood flow in a small-caliber arterial graft can suppress acute thrombus formation by affecting the adhesion of platelets to the internal surface of the graft, an experimental comparative study was designed to investigate the effect of swirling flow on the adhesion and activation of platelets in a straight glass tube coated with calf skin type I collagen. The experimental results showed that when compared with the normal flow, the swirling flow generated in the test tube significantly reduced the platelet adhesion to the surface of the test tube. Different from normal flow condition under which platelet adhesion increased simply with decreasing wall shear stress, the platelet adhesion density under swirling flow condition remained almost unchanged along the first 5 mm section of the tube in which the flow had relatively high rotation strength, even though the wall shear stress in this section of the tube dropped drastically. This suggests that when the swirling flow in the tube was strong enough, platelet adhesion was dominantly affected by the swirling flow itself, wall shear stress was secondary. The results also showed that there was no significant difference in the activation of platelets between the spiral flow group and the normal flow group. The present study therefore suggests that intentionally introducing swirling flow in small-caliber arterial grafts has no adverse effect on platelet activation and may indeed be a solution to improving the patency of the grafts by suppressing acute thrombus formation.

Use of low molecular weight heparin for thromboprophylaxis in a pediatric inpatient population: Reasons for use and incidence of bleeding complications - Corrected Proof

Matthew Cavo, Wei Wang, Sarah H. O'Brien — 2010-02-22

The majority of hospitalized adults have at least one risk factor for deep venous thrombosis (DVT) . Such risk factors include surgery, trauma, immobility, malignancy, obesity, and central venous catheters. Accordingly, guidelines have been developed for the use of pharmacologic and/or mechanical thromboprophylaxis in acutely ill medical patients, trauma patients, and even otherwise healthy patients undergoing certain types of surgeries . For most indications, low-molecular-weight heparin (LMWH) or low-dose unfractionated heparin appear to be the most efficacious form of thromboprophylaxis.

Role of 4G/5G promoter polymorphism of Plasminogen Activator Inhibitor-1 (PAI-1) gene in outcome of sepsis - Corrected Proof

2010-02-22

Serious infections trigger a systemic inflammatory response which results in sepsis. Severe sepsis is sepsis complicated by organ dysfunction and when sepsis results in hypotension despite adequate fluid resuscitation, it is called septic shock having a poor prognosis . Even though significant advances, both in supportive care and in understanding its molecular bases, sepsis is the most common cause of death among patients in an intensive care unit (ICU) . The innate immune system acts releasing cytokines and mediators that stimulate the adaptive immune responses although these are injurious to various tissues and organs . It is possible that the persistence of high concentration of certain proinflammatory cytokines or the incapacity of raising certain cytokines at a specific moment might perpetuate the inflammatory response resulting in sepsis or septic shock .

Clinical and laboratory factors associated with shear-dependent platelet hyper-reactivity in patients on chronic aspirin therapy - Corrected Proof

2010-02-22

The Platelet Function Analyzer-100® (PFA-100) assesses agonist-induced platelet aggregation under high shear by measuring the closure time (CT) of a membrane aperture by the formation of a platelet plug . The two agonist cartridges currently available are designed to screen patients for defects in primary hemostasis: The collagen/epinephrine (CEPI) agonist cartridge detects the antiplatelet effects of aspirin and the collagen/ADP (CADP) agonist cartridge, which is not influenced by aspirin, is useful in identifying patients with acquired and congenital platelet disorders such as von Willebrand disease . With both agonist cartridges, prolongation of the CT beyond the normal range indicates inhibited or impaired platelet function. Recent evidence also suggests that the PFA-100 has utility in identifying patients with platelet hyper-reactivity, indicated by an abnormally low CT. In patients with cardiovascular disease, a CEPI CT in the normal range despite aspirin therapy has been associated with an increased risk of recurrent cardiovascular events . A CADP CT below the normal range, indicative of enhanced global platelet reactivity, has been observed in patients with acute coronary syndromes and found to correlate both with the degree of myocardial damage and with recurrent ischemic events .

Platelet response as a sentinel marker of toll-like receptor 4 activation in mice - Corrected Proof

Muthuvel Jayachandran, Virginia M. Miller, Gregory J. Brunn, Whyte G. Owen — 2010-02-22

Chronic low grade infection with Gram negative organisms, inferred from traces in plasma of endotoxin, or lipopolysaccharide (LPS), has been linked to ischemic vascular disease . Low level bacteremia in nominally healthy individuals may be a normal state involving commensal organisms and can arise from activities as routine as tooth brushing . Innate immune responses to Gram negative bacteria involve interaction of bacterial LPS with toll-like receptor 4 (TLR4), which occurs on the surface of most cells, including platelets . TLR4 signaling in nucleated cells proceeds through the NF-κB pathway to stimulate diverse reactions, including production of cytokines such as TNFα . While mechanisms are not clear, platelets contain an NF-κB family of signaling complexes , and appear to participate in innate immune responses . In these and other studies of platelet economy in inflammation, LPS has been administered in doses that emulate processes associated with sepsis. Much lower levels of LPS associated with low level bacteremia have received little attention, in spite of some evidence that it may be a factor in vascular disease.

Antiplatelet effects of aspirin with phytosterols: Comparison with non-enteric coated aspirin alone - Corrected Proof

2010-02-22

Abstract: The novel combination of aspirin and phytosterols may be a potential strategy to treat patients with cardiovascular disease. We sought to determine if the antiplatelet effects of a combination caplet of 81 mg aspirin with 400 mg phytosterols differed from the antiplatelet effects of non-enteric coated aspirin. The first five days of aspirin therapy alone (T1) produced marked reductions in collagen-induced, ADP-induced, and archidonic acid- induced platelet aggregation, and in serum and urine TxB2 compared to baseline. Five days after randomization to aspirin alone versus aspirin+phytosterols (T2), there were no differences in any measurement of platelet function within each group compared to T1 or between groups. The present study suggests that the antiplatelet effect of non-enteric coated 81 mg twice-daily aspirin therapy alone is not affected by the addition of phytosterols in a combination product.

An analysis of clinical outcomes of 91 pregnancies in 83 women treated with danaparoid (Orgaran®) - Corrected Proof

H.N. Magnani — 2010-02-22

Abstract: Danaparoid case reports of 91 pregnancies in 83 patients with a history of thrombophilia and/or intra-uterine growth retardation have been analysed. All had intolerance to the heparins including HIT and acute or past thromboses or a history of repeated pregnancy loss (RPL).Danaparoid was started in the first, second and third trimesters in 60.2%, 19.3% and 20.5% pregnancies respectively at a dosing intensity of 1000 to 7500 U/day. Subcutaneous and/or intravenous administration was continued for a median 105 days (range 1-252) during pregnancy and 7 days (range 2 to 56) post-partum.The live birth rate was 90.4% (75/81) and danaparoid was restarted after 37 deliveries. Maternal adverse events in 46.2% of the pregnancies included 2 post caesarian deaths (a failed post-operative resuscitation and a major bleed in a patient refusing transfusion), 3 non-fatal major bleeds (associated with caesarian section and faulty placental implantation), 3 thrombo-embolic events unresponsive to danaparoid dose increase and 10 recurrent rashes.Seven early miscarriages, 1 therapeutic termination and 1 neonatal death occurred. In 13 reports a maternal, but no fetal, adverse event was attributed to danaparoid.Anti-Xa activity levels in maternal plasma were between 0.1 and 1.2 U/mL, absent from 6 fetal cord blood samples and 0 – 0.07 U/mL in the 5 maternal breast milk samples tested.Conclusion: The successful birth rate and adverse event profile indicates that danaparoid can be an effective and safe alternative anti-thrombotic in pregnancies complicated by HIT or intolerance or resistance to (LMW)heparins.

Thienopyridine and cilostazol are safer for gastroduodenal mucosa than low-dose aspirin – second report of endoscopic evaluation - Corrected Proof

2010-02-22

To the editor Recent researches have indicated that antiplatelet agents such as thienopyridine increase risks of gastrointestinal bleeding as well as low-dose aspirin, and co-administration of acid suppressants are recommended . However, there is little endoscopic evidence of mucosal injury in patients taking antiplatelet agents other than aspirin . Previously we reported the prevalence of gastroduodenal mucosal injury in patients on antiplatelet therapy . From the results, the possible difference of the frequency of mucosal injury among antiplatelet medicines was suggested, although the difference remained insignificant due to small sample number. Here we conducted the study to clarify whether the trend is true, by increasing sample number. From all 5555 patients undergoing esophagoduodenogastroscopy from 2005-06 at the Department of Internal Medicine of Teikyo University Hospital (Tokyo, Japan), 618 consecutive patients who had taken at least one of the antiplatelet agents, low-dose aspirin (less than 100mg/day), ticlopidine (Panaldine®, Sanovi Aventis Co., Tokyo, Japan), clopidogrel (Plavix®, Sanovi Aventis) or cilostazol (Pletaal®, Otsuka Pharmaceutical Co., Tokyo, Japan) were selected as study subjects. As control subjects, we selected 137 patients (94 males, 43 females; 68.1±7.1) over 60years of age who underwent an upper gastrointestinal endoscopy for screening malignancy during same period. Patients taking either NSAIDs, antiplatelets, proton pump inhibitors or histamine 2 receptor antagonists were excluded from the subjects. The subjects’ endoscopic records were retrospectively evaluated by two well-trained examiners with over 10years experience (T.Y and Y.K), to judge for the presence of gastroduodenal mucosal injury, with examiners blinded to patient data. Mucosal injury was defined as obvious findings of gastroduodenal mucosal defects (ulcer or erosion). If the two examiners differed in opinion, another examiner evaluated the record again to make the final diagnosis. Background characteristics of the subjects including age, gender, underlying disease, reason for undergoing examination, past history of gastroduodenal ulcer and concomitant administration of angithrombotic drugs, acid suppressants, or other gastroprotective agents, were ascertained from medical records. The presence of serum anti-Helicobacter pylori (H.pylori) antibody was tested using a commercially available kit (E-plate®, Eiken Chemical Co., Tokyo, Japan) in participants who gave written informed consents. The prevalence of mucosal injury were compared between the control group and the five medication groups; low-dose aspirin (Asp), clopidogrel/ticlopidine (Thi), cilostazol (Cil), Asp + Thi, Asp + Cil, Asp + Thi + Cil. Unadjusted odds ratios and 95% confidence intervals were calculated to clarify the statistical significance of differences between two groups, if appropriate. Prior to the study, the protocol was approved by the institutional review board of Teikyo University.

Soluble CD40L in Mediterranean Spotted Fever: Relation to oxidative stress and platelet activation - Corrected Proof

2010-02-22

The spotted fever diseases result from infection with insect vector-transmitted rickettsial organism. The pathophysiological hallmark of these diseases includes infection of endothelial cells with subsequent infiltration of inflammatory cells, resulting in vasculitis .

Trends in mortality of pulmonary embolism – an international comparison - Corrected Proof

Barbara Hoffmann, Christian R. Gross, Karl-Heinz Jöckel, Knut Kröger — 2010-02-22

Abstract: Background: Evidence from several clinical and epidemiological studies suggests a decreasing incidence and mortality of pulmonary embolism (PE), but results are still controversial. We analysed time trends of fatal pulmonary embolism in several countries across Europe and North America.Methods: We extracted age-, sex-, and country-specific number of deaths due to PE (415.1 ICD-9; I26 ICD-10) from 1980 to 2004 as available from the WHO mortality database, which comprises mortality data and population density in 5-year age groups based on national vital statistics. Yearly age- and sex-standardised mortality rates and their 95% confidence intervals for PE were calculated. We compared overall and sex-specific age-standardised mortality rates across different European countries and the USA over time.Results: Age- and sex-standardised PE-specific mortality in 1990 varied between 2.7/100,000 (2.5-3.0/100,000) in The Netherlands and 12.8/100,000 (12.0-13.5/100,000) in Austria. While in most countries PE mortality decreased over time, PE mortality increased distinctly in Poland from 4.0/100,000 (3.75-4.27/100,000) to 7.7/100,000 (7.45-8.03/100,000) in 2003. In Germany, we observed a continuous slight increase and in The Netherlands no clear change of PE mortality was seen.Discussion: While comparison of cause of death data over time and across countries should be undertaken with caution due to inaccuracies in assigning the cause of death and national conventions in coding, the general trend of a decline in PE mortality could not be shown in several European countries.

A randomised study comparing the antiplatelet and antinflammatory effect of clopidogrel 150mg/day versus 75mg/day in patients with ST-segment elevation acute myocardial infarction and poor responsiveness to clopidogrel: Results from the DOUBLE study - Corrected Proof

2010-02-22

Abstract: Introduction: The antiplatelet effect of standard or increased clopidogrel doses in patients with ST- segment elevation acute myocardial infarction (STEMI) has never been studied. In this study we compared the antiplatelet effect of a 75mg daily maintenance dose of clopidogrel with 150mg in patients with STEMI undergoing primary percutaneous coronary intervention (PCI).Materials and methods: Fifty-four patients with STEMI undergoing PCI were randomly allocated to receive either 75mg/day clopidogrel (group 1) or 150mg/day (group 2) for 1month. Platelet function, measured by 5 different assays, was determined at 3 time points: 38±8 hours after the procedure, 1week and 1month after randomization.Results: In group 1, mean ± SD platelet reactivity index (PRI) measured with the VASP assay was 57.7±15.7% and 46.9±15.7% at 1week and 1month, respectively, compared to 38.8±15.7% and 34.9±12.6% in group 2 (p=0.0001). Same results were observed for light transmittance aggregometry, whole blood aggregometry and VerifyNow, but not for thromboelastometry. In contrast to what may be expected, the 75mg daily maintenance dose took longer than 1-week to provide the full clopidogrel antiplatelet effect. Furthermore, patients in group 2 had a nearly 50% reduction in C-reactive protein levels both at 1week and 1month.Conclusion: In patients with STEMI and poor responsiveness to clopidogrel a 150mg daily maintenance dose of clopidogrel is associated with a significant reduction of platelet aggregation and a trend towards reduced inflammation.

Risk of deep venous thrombosis (DVT) in bedridden or wheelchair-bound multiple sclerosis patients: A prospective study - Corrected Proof

2010-02-22

Abstract: Background: Multiple sclerosis (MS) often causes progressive loss of mobility, leading to limb paralysis. Venous and lymphatic stasis is a risk condition for venous thromboembolism (VTE). There is, however, no data on the frequency of VTE complicating the progression of MS. The aim of this study was to assess the frequency of deep vein thrombosis (DVT) in patients with late-stage MS attending a neurology center for rehabilitation.Patients and Methods: A total of 132 patients with MS were enrolled, 87 women and 45 men, mean age 58±11 years. The disease had started on average 18.7 years before; patients reported 9.6 hours bedridden per day or 14.3 hours wheelchair-bound. Only 25 patients reported a residual ability to walk alone or with help. Lower limb edema was present in 113 patients, bilateral in 41 cases. At admission all patients underwent extended compression ultrasonography. Their plasma D-dimer levels were measured. No antithrombotic prophylaxis was given.Results: DVT was found in 58 patients (43.9%); 32 had a history of VTE. Forty of these patients (69%) had chronic lower limb edema, in 19 cases bilateral. D-dimer levels in the DVT patients were significantly higher than in patients without DVT (553±678 vs. 261±152 ng/mL, p=0.0112, Mann-Whitney Test). Nearly half the DVT patients (26, 45%) had high D-dimer levels (701±684 ng/mL). Of the 74 patients without DVT, 48 had normal D-dimer (193.37±67.28 ng/mL) and 26 high (387.61±187.42 ng/mL).Conclusions: The frequency of DVT in late-stage MS may be over 40%. The long history of the disease means the onset of each episode cannot be established with certainty. A number of patients with positive CUS findings had negative D-dimer values, suggesting a VTE event in the past. However, the level of DVT risk in this series should lead physicians to consider the systematic application of long-term preventive measures.

Risk of thrombosis and infections of central venous catheters and totally implanted access ports in patients treated for cancer - Corrected Proof

M.M.J. Beckers, H.J.T. Ruven, C.A. Seldenrijk, M.H. Prins, D.H. Biesma — 2010-02-22

Abstract: Introduction: Thrombosis and infections are well known complications of central venous catheters and totally implanted access ports. These complications lead to increased costs due to prolonged hospitalisation, increased antibiotics use and need for replacement.The objectives of the study were to document the occurrence of catheter related thrombosis and infections in patients with central venous catheters and totally implanted chest ports in cancer patients and to investigate whether factor V Leiden is a risk factor for catheter related thrombosis.Materials and methods: Between February 2002 and November 2004, 43 patients with central venous catheter or totally implanted access port were followed up to document the occurrence of catheter related thrombosis and infections. Patients received chemotherapy either for haematological malignancy or for solid tumours. Factor V Leiden (R506Q) was determined by restriction fragment length polymorphism analysis. Follow-up period ended in April 2007.Results: Catheter related thrombosis occurred in 4 patients (4/43; 9.3%) with a totally implanted access port. None of the 3 patients with factor V Leiden had catheter related infection or thrombosis. Catheter related infections occurred in 15 patients: 10 patients (23.3%; 10/43) with central venous catheter and 5 patients (11.6%; 5/43) with totally implanted access ports. Time to infection was 32.5days in the central venous catheter group compared to 88days in the totally implanted access port group.Conclusion: A higher incidence of catheter related infections was observed in patients with central venous catheters in contrast to patients with totally implanted access ports were venous thrombosis was more frequent.

Prior simvastatin treatment is associated with reduced thrombin generation and platelet activation in patients with acute ST-segment elevation myocardial infarction - Corrected Proof

2010-02-22

Abstract: Background: It has been reported that statin therapy produces additional effects including impaired activation of blood coagulation. It is not clear whether statins can affect hemostasis in patients with acute coronary syndrome. The aim of this study was to investigate the effect of prior statin treatment on thrombin generation and platelet activation in patients with ST-segment elevation myocardial infarction (STEMI).Methods: We studied 53 consecutive STEMI patients admitted within 12 hours of pain onset, including 19 treated with simvastatin (40 mg/d) (simvastatin group) at least one month prior to STEMI, and 34 not receiving any statins (no-statin group) on admission. Thrombin-antithrombin (TAT) complexes generation and soluble CD40 ligand (sCD40L) release were determined in 60-second blood samples collected at the site of microvascular injury.Results: There were no significant intergroup differences with respect to clinical and laboratory variables, including plasma TAT and sCD40L levels, except lower total cholesterol and low-density lipoprotein cholesterol in the simvastatin group. The mean maximum rate of TAT generation was 47.5% lower (p=0.0002) and sCD40L release 33.3% lower (p=0.0006) in the simvastatin group. Total amounts of TAT (p<0.0001) and sCD40L (p=0.002) collected within 5 minutes of bleeding were lower in simvastatin-pretreated patients. By multivariate regression analysis, variables describing local TAT and sCD40L profiles in the whole group were independently associated with simvastatin pretreatment (p<0.0001), but not with cholesterol, platelet count or troponin levels.Conclusions: Prior simvastatin use is associated with lower thrombin generation and platelet activation following vascular injury in the early phase of STEMI.

Correlation of thromboelastography with standard tests of anticoagulation in paediatric patients receiving extracorporeal life support - Corrected Proof

2010-02-22

Abstract: Children requiring extracorporeal life support (ECLS) are at significant risk for thrombotic and haemorrhagic complications. Thromboelastography (TEG) is increasingly being used to assist in monitoring the coagulation status of critically ill patients. Its role in heparinised children receiving ECLS is unknown.Methods: A retrospective review of TEG in 27 children (mean age 2years and 8months) receiving ECLS in a tertiary paediatric intensive care unit between December 2006 and April 2008. Paired TEG (kaolin and heparinase) analysis was performed on 171 occasions. On all occasions activated partial thromboplastin time (APTT) and platelet count were performed within 4 hours of the TEG (mean 6.5 minutes after TEG). On 158 occasions, the activated clotting time (ACT) was measured simultaneously with TEG.Results: The TEG (kaolin) sample was not interpretable due to the heparin effect in 89 (52%) samples. There was a weak correlation between TEG (heparinase) variables and APTT, and between TEG and ACT with a stronger correlation between TEG (Maximum amplitude) and platelet count.Conclusion: TEG monitoring should always include paired samples in heparinised children on ECLS. In this heterogeneous population, weak, and moderate correlations exist between TEG and standard haematological tests. Prospective studies, with simultaneous sampling for TEG and conventional laboratory tests, must be performed in order to establish its absolute utility as a clinical tool in this population.

Single-dose adjustment versus no adjustment of warfarin in stably anticoagulated patients with an occasional international normalized ratio (INR) out of range - Corrected Proof

S. Schulman, A. Melinyshyn, D. Ennis, L. Rudd-Scott — 2010-02-22

Abstract: Background: Well-controlled patients on warfarin may still have occasional International Normalized Ratios (INRs) outside the therapeutic range. It is unclear whether there is any benefit of a single-dose correction in this situation.Aim: To evaluate whether patients with very stable INR results should continue with the maintenance dose of warfarin without a single-dose correction, even when the result unexpectedly is moderately below or above the therapeutic range.Methods: A) We reviewed retrospectively 364 patients with unchanged maintenance dose for at least 6 months and an occasional INR outside the therapeutic range regarding decision on dosing and the effect on the next INR. B) We randomized 160 patients with at least 3 months of unchanged maintenance dose, an occasional INR deviating to a minimum of 1.5 or a maximum of 4.4 and unexplained or temporary, removable cause to a single-dose Change or No change. Follow-up INRs and telephone interviews were obtained after 2 weeks.Results: A) Retrospectively, the proportion of follow-up INRs outside the therapeutic range was 29.9% after No change, 27.1% after Increased dose and 25.7% after Skipped/reduced dose. However, the decision on No change was mainly taken in case of minimal INR deviations. B) Forty-eight (60%) of the patients randomized to Change were within the therapeutic range at follow-up versus 45 (56%) of those with No change, odds ratio 1.17 (95% confidence interval 0.59-2.30). For baseline INRs deviating down to 1.6 or up to 3.6 (therapeutic range, INR 2.0-3.0) the 2-week INRs did not differ between the groups.Conclusion: Our results suggest only a small or no difference between the two managements of an occasional INR out of range in terms of the 2-week follow-up INR. In stable patients on warfarin with an occasional INR outside the therapeutic range it seems reasonable to continue with the same dose without a single-dose change and perform a repeat test in about 2 weeks. (ClinicalTrials.gov number, NCT00814177.)

Multicenter evaluation of a new quantitative highly sensitive D-dimer assay, the Hemosil® D-dimer HS 500, in patients with clinically suspected venous thromboembolism - Corrected Proof

2010-02-22

Abstract: Introduction: D-dimer testing is widely used in conjunction with clinical pretest probability (PTP) for venous thromboembolism (VTE) exclusion. We report on a multicenter evaluation of a new, automated, latex enhanced turbidimetric immunoassay [HemosIL® D-Dimer HS 500, Instrumentation Laboratory (IL)].Materials and Methods: 747 consecutive outpatients with suspected proximal deep vein thrombosis (DVT, n=401) or pulmonary embolism (PE, n=346) were evaluated at four university hospitals in a management study with a 3 month follow-up. Samples were tested at each center using the new D-dimer assay on an automated coagulation analyzer [ACL TOP (IL)], with clinical cut-off for VTE at 500 ng/mL (FEU).Results: The sensitivity and negative predictive value (NPV) were 100% for all PTP subgroups (no false negative results); for both sensitivity and NPV the lower limit of the 95% CI in patients with moderate/low PTP was higher than 95%. The overall specificity was 45.1% (95%CI: 41.1-49.3%). Higher specificity value was recorded in the low PTP subgroup [49.2% (95%CI: 41.7-56.7)]. No significant differences were found between patients suspected of having DVT or PE; sensitivity and NPV were 100%. The reproducibility of the assay was good, being the total CVs% less than 10% for D-dimer concentration near the clinical cut-off.Conclusions: The new, highly sensitive D-dimer assay proved to be accurate when used for VTE diagnostic work-up in outpatients. Based on 100% sensitivity and NPV and lower limit of the 95% CI higher than 95%, the assay can be used as a stand-alone test in patients with non high PTP.

Analysis of unfractionated heparin dose requirements to target therapeutic anti-Xa intensity during pregnancy - Corrected Proof

Nathan P. Clark, Thomas Delate, Steven J. Cleary, Daniel M. Witt — 2010-02-22

Abstract: Introduction: Unfractionated heparin (UFH) does not cross the placenta and has demonstrated utility in the prevention and treatment of thrombosis during pregnancy. Limited information is available to guide initiation and monitoring of therapeutic UFH targeting an anti-Xa concentration of 0.3-0.7 u/ml during pregnancy. The objective of this study was to describe UFH doses and monitoring strategies required to achieve and maintain therapeutic anti-Xa intensity in a cohort of women treated with UFH during pregnancy.Materials/Methods: Patients prescribed anti-Xa adjusted UFH during pregnancies occurring between January 1998 and March 2005 were included.Results: A total of 39 pregnancies for 37 women were identified. Unfractionated heparin doses were titrated to achieve a mid-interval anti-Xa level of 0.3-0.7 u/ml. Patients required a median 6.5 days and a mean UFH dose of 403.5 u/kg/day to achieve therapeutic anti-Xa levels. Most anti-Xa levels were within the target range (59%). The final UFH dose/kg required at the end of pregnancy was similar to that at the first therapeutic level (P>0.05); however some patients did require dose modification. Patients required a mean 14.1 anti-Xa determinations and 4.6 dose modifications during a mean 23.9 weeks of antenatal UFH therapy. Patient weight and UFH dose at the first therapeutic anti-Xa level were correlated (r=0.383, P=0.018).Conclusions: Pregnant women required a mean UFH dose of 403.5 u/kg/day to achieve midinterval anti-Xa levels of 0.3-0.7 u/ml. The required dose was correlated with patient weight and most anti-Xa measurements were within the target range.

Should the factor V Leiden mutation be screened among ethnic Malays with venous thrombosis? - Corrected Proof

H.J. Ng, E.S. Koay, A. Abdul Ghafar, L.C. Lim, L.H. Lee — 2010-02-22

In the screening of thrombophilia among our patients with recent venous thromboembolism (VTE), we currently strongly recommend against testing for the factor V Leiden (FVL) mutation in ethnic Chinese. The near absence of this prothrombotic marker among Orientals is well demonstrated by numerous studies , including one of our own . We are much less certain about the futility of FVL testing among ethnic Malays who make up 15% of the Singapore population , as there is very limited published prevalence data of FVL for this group. In our previous study, the prevalence of FVL among healthy ethnic Malays was estimated to be 0.5% . Among hospitalized patients in Singapore, the prevalence of venous thrombosis is equally distributed along ethnic lines Therefore, despite being a minority group in our city state, the decision on whether to screen for FVL in Malays with thrombosis is not an uncommon dilemma in clinical practice. This problem is amplified in the region as the Malay diaspora is extensively spread across Malaysia, Brunei, southern Thailand, parts of Indonesia and Borneo. Furthermore, as one of the Austronesian-speaking people, Malays are genetically close to many more ethnic groups populating South-east Asia, Oceania and parts of Southern Africa such as Madagascar .

Endothelin-1 in acute pulmonary embolism - Corrected Proof

Matteo Sofia, Mauro Maniscalco — 2010-02-22

We have read with interest the paper by Kostrubiec et al. published in the June issue of this journal . In their study the Authors evaluated circulating levels of endothelin-1 ( ET- 1) in a large sample of patients with acute pulmonary embolism (PE). According to our previous report , they found that plasma endothelin concentrations assessed on venous blood samples were not elevated in patients with acute PE as compared to control subjects, concluding that it does not play an important role in the acute phase of PE.

Impaired fibrin gel permeability by high homocysteine levels - Corrected Proof

Irene L. Quintana, María V. Oberholzer, Lucía Kordich, Ana M. Lauricella — 2010-02-22

Abstract: Mechanisms involved in the relationship between hyperhomocysteinemia and thrombosis are still unclear. In previous reports we have shown that high homocysteine concentrations led to more compact and branched fibrin networks than controls. These clots showed an impaired lysis associated to their architecture. The aim of this study was to evaluate the effects of homocysteine on permeation of clots obtained from plasma and purified systems.Fibrin gels were prepared with normal plasma incubated with homocysteine and, in the purified systems, with fibrinogen and factor XIII treated with the amino acid. Permeability constants (Ks) were determined through flow measurements.Linear regression curve between Ks values and homocysteine levels in the plasmatic assays showed a negative correlation coefficient, r=-0.997 (p=0.003). Ks of fibrin gels obtained from purified systems with fibrinogen incubated with homocysteine was (7.07±0.27)×10-9 cm2, control was (11.40±0.37)×10-9 cm2 (n=3; p<0.01). Ks of fibrin gels obtained with factor XIII treated with homocysteine was (1.47±0.17)×10-9 cm 2, and control was (3.31±0.31)×10-9 cm2 (n=3; p<0.01).Plasma incubated with high homocysteine concentrations produced fibrin clots significantly less permeable than controls in a dose dependent manner, and the results showed that fibrinogen and factor XIII were involved in that detrimental effect. These findings might explain the impaired fibrinolysis related to increased homocyteine levels and contribute to understanding the association between the amino acid and thrombosis.

WITHDRAWN: Retinal vein occlusion: Risk factors evaluation, treatment and prophylaxis - Corrected Proof

2010-02-22

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Baseline platelet size is increased in patients with acute coronary syndromes developing early stent thrombosis and predicts future residual platelet reactivity. A case-control study - Corrected Proof

2010-02-22

Abstract: Introduction: Pre-procedural predictors of early stent thrombosis (ST) and future response to platelet inhibitors are in demand. We sought to evaluate the impact of baseline platelet indices on the occurrence of early ST and future residual platelet reactivity.Materials and methods: Hundred and eight patients with acute coronary syndromes (ACS) in whom stents were implanted were included: 36 consecutive ST cases and 72 matched controls. Platelet indices assessed with flow cytometry before stent implantation were retrieved from the department's data base. Residual platelet reactivity specific to aspirin (aspirin reaction units–ARU) and clopidogrel (P2Y12 reaction units–PRU) was assessed prospectively with VerifyNow® under dual antiplatelet treatment.Results: Platelet size reported as mean platelet volume (MPV) or proportion of large platelets (LPLT) was significantly higher in ST cases compared with controls (10.4, 95% confidence intervals [CI], 10.1-10.8 vs. 9.7, CI, 9.5-9.9, P=0.0004 and 35.8, CI, 34.2-37.3 vs. 33.3, CI, 32.2-34.3, P=0.007, respectively). Dual aspirin and clopidogrel poor-responsiveness was diagnosed significantly more often in ST cases than in controls (19.6% vs. 1.4%, P=0.004), whereas no difference was observed for single aspirin or clopidogrel poor-responsiveness. A strong correlation was found between MPV and both, ARU (r=0.66, P<0.0001) and PRU (r=0.55, P<0.0001). Similarly, higher LPLT was associated with higher ARU (r=0.47, P<0.0001) and PRU (r=0.38, P=0.0001).Conclusions: Baseline platelet size is increased in patients with ACS developing early ST and correlates with future residual platelet reactivity under aspirin and clopidogrel therapy. Dual but not isolated aspirin or clopidogrel poor-responsiveness appears to be associated with early ST.

Androgen receptor polymorphism and platelet reactivity in healthy men - Corrected Proof

2010-02-22

There is established evidence of gender differences in the prevalence and severity of vascular thrombosis and mortality, with men having onset of coronary artery disease earlier in the life than women, and with first symptoms more often being myocardial infarction . The impact of sex hormones on gender differences in platelet activity (one of the main factors in atherothrombosis) is also being increasingly recognized . One of the “culprit” hormones which could play a role in that setting is testosterone, which seems to have an influence on platelet activity, although the available data are conflicting. Some experimental studies show that in castrated rats given testosterone to physiological levels, enhanced platelet aggregation present after castration and atherosclerotic plaque growth are inhibited . Testosterone deprivation can also be harmful in men with prostate cancer treated with anti-androgenic therapy . By contrast, in another study, exogenously administered testosterone up-regulated the population of thromboxane A2 (TXA2) receptors on platelets in healthy young male volunteers, and this was concomitant with an enhanced aggregation response to TXA2-mimetic I-BOP . In yet another study, the reduction in circulating testosterone concentration following castration was associated with a significant reduction in platelet TXA2 receptor density and maximum aggregation response to TXA2-mimetic I-BOP.

Endothelin and pulmonary embolism - Corrected Proof

Maciej Kostrubiec, Piotr Pruszczyk — 2010-02-22

In Reply, Dr Sofia and Dr Maniscalco suggested that endothelin (ET) although non-elevated in venous blood, can play important role in pathogenesis of pulmonary embolism (PE). They remind the study of ET abnormalities in PE, which revealed elevation of arterial/venous ET ratio in patients with PE compared to healthy volunteers. That study and well-documented increase of plasma ET in chronic thromboembolic pulmonary hypertension (CTEPH) inspired us to undertake our research . We hypothesized that plasma ET concentrations are not only elevated but also may reflect hemodynamic compromise assessed by systemic blood pressure and echocardiographic indices of right ventricular pressure overload. Unexpectedly, in our study plasma ET concentrations assessed on admission were not elevated in patients with acute PE. Therefore we suggested that in contrast to pulmonary arterial hypertension ET does not play an important role in acute pulmonary embolism even resulting in the acute pressure overload.

Treatment of the critically ill patient with protein C: Is it worth the cost? - Corrected Proof

Gunnar Nilsson, Sören Höjgård, Erik Berntorp — 2010-02-22

Abstract: Introduction: We have shown that low protein C levels predict poor survival up to five years in a general intensive care unit patient material and hypothesize that treatment with protein C is beneficial. The objectives were to calculate costs of protein C treatment, at best-case scenario, per statistical life saved.Materials and methods: Ninety-two patients with deranged global haemostatic tests admitted to the mixed surgical medical intensive care unit, Malmö University Hospital. We hypothesized that increasing protein C levels in patients with low levels would enhance survival to the same rate as a cohort with higher protein C. Number of statistical lives saved were estimated using survival analysis. Costs per life saved at 30days were calculated.Results: Total costs per life saved in 2007 prices (upper limit of 95% CI) were calculated at € 50,200 (recombinant activated protein C, drotrecogin alfa (activated), Xigris®) and € 46,000 (zymogen protein C, Ceprotin), which may be compared to the value of a statistical life (€ 937,000).Conclusions: Our theoretical model of converting a low protein C group to a higher protein C group by treating with activated protein C or the protein zymogen showed no major difference between the treatments in terms of costs, and that costs are lower than the value of a statistical life. Although our study has several caveats the results support the PROWESS study, in that patients with a very severe disease, having low protein C levels, may benefit from protein C treatment in a cost effective way.

Risk factors for failure of heparin thromboprophylaxis in patients with acute traumatic spinal cord injury - Corrected Proof

2010-02-22

Abstract: Venous thromboembolism (VTE) is a well-recognized complication of Acute Traumatic Spinal Cord Injury (ATSCI). Despite prophylaxis by heparins, VTE occurs in a substantial number of ATSCI patients without an obvious explanation. In this matched case-control study we examined whether thrombophilia and other risk factors are associated with failure of thromboprophylaxis.Cases and controls receiving heparin thromboprophylaxis were selected from consecutively admitted ATSCI patients. Patients who developed a new, objectively confirmed, symptomatic VTE despite prophylaxis at hospital were matched by gender, age, level and mechanism of ATSCI with 2-3 controls without VTE. Patients were interviewed about VTE risk factors and tested for factor V Leiden (FVL), prothrombin G20210A (PT), methylenetetrahydrofolate reductase C677T homozygosity (MTHFR), lupus anticoagulant, homocysteine (Hcy) and plasma factor VIII (FVIII) levels.Twenty-two patients with new VTE episodes and 64 controls were ascertained. The total number of gene alterations for MTHFR, FVL and PT or elevated levels of Hcy or FVIII was significantly more common in patients compared to controls (82% vs. 48%, p=0.006). Multiple logistic regression proved the PT mutation, a positive family history of thrombosis and elevated levels of either FVIII or Hcy to be predictors of thrombosis.Conclusion: A positive family history of VTE, carriership of the prothrombin mutation and elevated FVIII or Hcy levels were significantly associated with failure to prevent VTE by heparin therapy following ATSCI. Testing for thrombophilia in patients with ATSCI and possibly a more intense thromboprophylactic regimen seem desirable but need to be verified by a prospective study.

Factor V Leiden as risk factor for unexplained stillbirth – a population-based nested case-control study - Corrected Proof

2010-02-22

Abstract: Introduction: Stillbirth is a relatively uncommon pregnancy complication in developed countries yet causing strong emotional burden. Thrombophilia has been associated with stillbirth but population-based studies are few. We assessed selected genetic and acquired parameters for the risk of unexplained stillbirth, including FV Leiden.Materials and methods: We performed a population-based nested case-control study of 100,000 consecutive pregnancies in Finland. Cases and controls were identified by combining national registers and accepted according to strict criteria after checking their medical records. Stillbirth was defined as intrauterine fetal death ≥22weeks of gestation. We excluded stillbirths due to lethal congenital developmental conditions, umbilical cord complications, and infections. We studied 44 cases of unexplained stillbirth and 766 controls.Results: FV Leiden was associated with 3.8-fold (95% CI 1.2-11.6) risk for unexplained stillbirth, 3.9-fold (95% CI 1.1-13.9) risk for unexplained late stillbirth (≥28weeks of gestation), and 10.8-fold (95% CI 2.1-55.3) risk for unexplained stillbirth with placental lesions. The same figures for singleton pregnancies were 3.1-fold (95% CI 0.9-10.9), 4.3-fold (95% CI 1.2-15.3), and 10.6-fold (95% CI 2.1-54.3). Slightly increased risk associated with blood group O was not statistically significant. We found a trend for increased risk in advanced maternal age and smoking during pregnancy. High pre-pregnancy BMI was not associated with increased risk, nor was low educational level or first pregnancy.Conclusions: Our population-based study from a country with comprehensive prenatal care confirms the association between FV Leiden and unexplained stillbirth.

The effect of thyroid autoantibodies on warfarin stability - Corrected Proof

2010-02-22

A large proportion of patients on warfarin treatment spend up to half of their time outside the therapeutic range, with resultant increased risk of either thromboembolic or bleeding complications . While changes in concurrent medications, comorbidities, and patient's compliance affect the quality of control of anticoagulant therapy in a predictable way, intraindividual variability in the response to warfarin treatment remains often unexplained .

Increased microparticle tissue factor activity in cancer patients with Venous Thromboembolism - Corrected Proof

2010-02-22

Abstract: Cancer patients exhibit a high rate of thromboembolism (VTE). In this study, we analyzed levels of microparticle (MP) tissue factor (TF) activity in cancer patients with or without VTE. Blood was collected from cancer patients within 24 h of objectively diagnosed VTE (n=53) and from cancer patients without VTE (n=13). MPs were isolated from platelet poor plasma by centrifugation at 20,000g for 15 min. MP TF activity was measured using a two-stage chromogenic assay. Cancer patients with VTE had a significantly higher mean MP TF activity compared with cancer patients without VTE (1.7±3.8 pg/mL vs 0.6±0.4 pg/mL, p<0.05). Further prospective studies are required to determine if levels of MP TF activity may be a useful biomarker to identify patients at increased risk for VTE.

A Computerized Prompt for Thromboprophylaxis in Hospitalized Cancer Patients - Corrected Proof

2010-02-22

Hospitalization in cancer patients is increasingly complicated by the development of venous thromboembolism (VTE). In a study of the National Hospital Discharge Survey from 1979-99, 2% of hospitalized cancer patients had VTE, with rates approaching 4% in the late 1990s . In an analysis of cancer patients hospitalized from 1995-2003, 4.1% patients carried a diagnosis of VTE . Amongst patients receiving chemotherapy, rates also increased from 3.9% to 5.7%, an increase of 47% (P<.0001). VTE in cancer patients has significant consequences. Thromboembolism is a leading cause of death in cancer patients , and cancer patients with VTE have a significantly worse survival compared to those without VTE . In hospitalized cancer patients, VTE is associated with a two-fold increase in in-hospital mortality . Cancer patients with VTE are also more likely to develop both bleeding complications and recurrent VTE . VTE also leads to consumption of healthcare resources: in a retrospective analysis of cancer patients, the average cost of hospitalization for the index DVT episode was $20,065 in 2002 US dollars .

Home treatment in pulmonary embolism - Corrected Proof

2010-02-22

Abstract: Background: Limited data exist on the feasibility of providing outpatient care to patients with acute pulmonary embolism (PE).Methods: We conducted a multicenter randomized clinical trial in acute symptomatic PE to compare the efficacy and safety of early discharge versus standard hospitalization. A clinical prediction rule was used to identify low-risk patients. All patients were followed for three months. The primary outcomes were venous thromboembolic recurrences, major and minor bleeding, and overall mortality.Results: One hundred and thirty two low-risk patients with acute symptomatic PE were randomized to early discharge (n=72) or standard hospitalization (n=60). Overall mortality was 4.2% (95% CI, 0.5-8.9) in the early discharge group and 8.3% (95% CI, 1.1-15) in the standard hospitalization group (Relative Risk (RR) 0.5; 95% confidence interval [CI], 0.12-2.01). Non-fatal recurrences were 2.8% (95% CI, 1.1-6.6) in the early discharge group and 3.3% (95% CI, 1.3-8%) in the standard hospitalization group (RR 0.8; 95% CI, 0.12-5.74). The rates of clinically relevant bleeding were 5.5% in the early discharge group and 5% in the standard hospitalization group (P=0.60). Short-term mortality was 2.8% (95% CI, 0.8-9.6%) in the early discharge group as compared with 0% in the standard hospitalization group. Based on the rate of short-term death in a carefully selected population, the study was suspended.Conclusions: In spite of the number of complications in patients with acute symptomatic PE randomized to standard hospitalization or early discharge did not differ significantly. The rate of short-term mortality was unexpectedly high in a (a priori) low-risk group of patients with acute PE. The accuracy of clinical prediction scores needs to be validated in well designed clinical trials. (ClinicalTrials.gov number, NCT00214929.)

Fibrinolysis and von Willebrand factor in Alzheimer's disease and vascular dementia – a case-referent study - Corrected Proof

Nils-Olof Hagnelius, Kurt Boman, Torbjörn K. Nilsson — 2010-02-22

A common finding in patients with myocardial infarction is an impaired function in the fibrinolytic system, mainly due to increased mass concentration of tPA and PAI-1 in plasma which are considered as primary risk factors of cardiovascular disease . Hemostasis has been proposed as a possible pathogenetic factor in dementia, especially vascular dementia . To our knowledge there is only one study by Mari et al in which endothelial derived fibrinolytic markers and vWF have been evaluated in AD vs. VaD patients.

Residual platelet reactivity after aspirin administration in pediatric patients - Corrected Proof

2010-02-22

Dear Sir, Aspirin is used to prevent thrombotic events, however, with variable antiplatelet activity in individual patients. Residual platelet reactivity can be detected in up to 61% of patients on aspirin therapy using different laboratory tests of platelet function . Aspirin is one of the most commonly prescribed antiplatelet agents in children, especially in those with congenital heart disease. These patients usually undergo complex intracardiac surgical procedures or percutaneous implantation of potentially thrombogenic intracavitary devices. The need to identify a group of low/non-responders to aspirin among pediatric patients is therefore of upmost clinical importance. An accurate and widely accepted method to assess aspirin resistance has not been established yet, neither in adults nor in the pediatric population . However, most data on children came from observational studies and to the best of our knowledge no studies exist that prospectively compare two widely accepted methods of platelet function assessment. It is also unknown whether increasing aspirin dosage may have any significant effect in the therapeutic response. The goal of the present study was to evaluate aspirin resistance in pediatric patients with congenital heart disease comparing two methods of assessing platelet function, PFA 100® and light transmission aggregometry and to investigate whether an increase of aspirin dose to in total 6mg/kg/d in patients presented with PFA 100® <165sec closure time may be of any effect.

Tissue factor-induced Thrombin Generation in the Fasting and Postprandial State among Elderly Survivors of Myocardial Infarction - Corrected Proof

Samira Lekhal, Trond Børvik, Ellen Brodin, Arne Nordøy, John-Bjarne Hansen — 2010-02-22

Abstract: Introduction: Tissue factor (TF)-induced thrombin generation (TG) ex vivo has been suggested to be an important method to assess thrombotic risk. No studies have investigated the impact of postprandial lipemia on TF-induced TG. Since myocardial infarction (MI) is associated with elevated postprandial levels of triglycerides, we hypothesized a differential impact of postprandial lipemia on coagulation activation in MI-patients and healthy controls.Material and Methods: Elderly survivors of acute MI (n=44) and healthy age-and sex matched controls (n=43) underwent a fat tolerance test (1 gram per kg body weight) to assess coagulation activation during postprandial lipemia.Results: The incremental area under the curve (AUCi) for serum triglycerides was higher in MI-patients than in healthy age-and sex matched controls (5.64±0.52mmol/L⁎h and 3.94±0.39mmol/L⁎h, p=0.012) during the postprandial phase. Subsequent endogenous activation of coagulation, assessed by FVIIa and thrombin generation (F1+2), was similar among groups and not related to levels of triglycerides during the postprandial phase. Healthy individuals had a gradual decline in TF-induced thrombin generation ex vivo, assessed by endogenous thrombin potential (ETP) (AUCi=-542.4±71.4nM⁎min⁎h, p<0.001), whereas MI-patients retained their ETP (AUCi=127.4±89.0nM⁎min⁎h, p=0.47) in plasma during the postprandial phase (p for group difference=0.005).Conclusions: MI-patients had elevated postprandial lipemia and retained their ability for TF-induced TG in plasma ex vivo in the postprandial phase, whereas the capacity gradually decreased in healthy individuals. Further studies are warranted to reveal underlying mechanism(s) and clinical implications.

Poor performance with a platelet counting technique to monitor clopidogrel inhibitory effects in the point-of-care setting - Corrected Proof

2010-02-22

Platelets play a central role in the pathophysiology of acute coronary syndromes (ACS) and dual antiplatelet therapy with aspirin and clopidogrel has resulted in significant treatment advances. However, there is important variability in the responsiveness to clopidogrel treatment, and there is an increasing use of point-of-care methods to evaluate clopidogrel responsiveness at the individual level. Currently, there are several point-of-care techniques for testing of platelet inhibition in clinical use, each with their strengths and limitations .