von Willebrand factor/factor VIII concentrate (Wilate) prophylaxis in children and adults with von Willebrand disease

ABSTRACT

Long-term prophylaxis with a von Willebrand factor (VWF) concentrate is recommended in patients with von Willebrand disease (VWD) who have a history of severe and frequent bleeds. However, data from prospective studies are scarce. WIL-31, a prospective, noncontrolled, international phase 3 trial, investigated the efficacy and safety of Wilate prophylaxis in severe patients with VWD. Male and female patients 6 years or older with VWD types 1, 2 (except 2N), or 3 who had completed a prospective, 6-month, on-demand, run-in study (WIL-29) were eligible to receive Wilate prophylaxis for 12 months. At baseline, patients (n = 33) had a median age of 18 years. Six (18%) patients had severe type 1, 5 (15%) had type 2, and 22 (67%) had type 3 VWD. The primary end point of a >50% reduction in mean total annualized bleeding rate (TABR) with Wilate prophylaxis vs prior on-demand treatment was met; mean TABR during prophylaxis was 5.2, representing an 84.4% reduction. The bleeding reduction was consistent across age, sex, and VWD types. The mean spontaneous ABR was 3.2, representing an 86.9% reduction vs on-demand treatment. During prophylaxis, 10 (30.3%) patients had 0 bleeding events and 15 (45.5%) patients had 0 spontaneous bleeding events. Of 173 BEs, 84.4% were minor and 69.9% treated. No serious adverse events related to study treatment and no thrombotic events were recorded. Overall, WIL-31 showed that Wilate prophylaxis was efficacious and well-tolerated in pediatric and adult patients with VWD of all types. The WIL-29 and WIL-31 trials were registered at www.ClinicalTrials.gov as #NCT04053699 and #NCT04052698, respectively.

Study of Platelet Agglutination Induced by the Antibiotics of the Vancomycin Group: Ristocetin, Ristomycin, Actinoidin and Vancomycin

Four antibiotics which belong to the vancomycin group have been examined in respect of their effects on the factor VIII dependent platelet agglutination. A striking similarity between ristocetin and ristomycin was observed both in qualitative and quantitative terms, therefore ristomycin could be used to determine the so called ristocetin cofactor.

Actinoidin and vancomycin inhibited platelet agglutination induced by ristocetin or ristomycin in citrate-PRP or EDTA-PRP as well as in systems containing formaldehyde- treated platelets, but did not inhibit agglutination induced by bovine factor VIII.

All the four antibiotics caused plasma protein precipitation. Actinoidin was the least and vancomycin the most effective in this respect; ristocetin and ristomycin also possess this property, the effect of the latter is more considerable.

Actinoidin and vancomycin did not block the immediate increase in light absorbancy in aggregometer caused by the addition of ristocetin or ristomycin to fixed platelets at concentrations which totally inhibited platelet agglutination in the presence of protein cofactor. Inhibition of this »direct effect« of ristocetin and ristomycin was observed only at higher concentrations indicating that this effect may be unrelated to the agglutination.

According to our results with ristomycin derivatives the methylated carboxyl and the free phenolic hydroxyl groups may be of prime importance in the binding of ristomycin to the platelet membrane and/or to its protein cofactor. Similar data from other laboratories are confirmed and some new findings are offered.

Comparison of the O’Brien Filter Test and the PFA-100 Platelet Analyzer in the Laboratory Diagnosis of von Willebrand’s Disease

Von Willebrand’s disease (vWD) is the most common congenital haemorrhagic diathesis, characterized by the quantitative or qualitative disorder of von Willebrand factor (vWF). A number of methods have been used for the diagnosis of the disease, and the bleeding time determination is widely accepted as a screening test in spite of its low sensitivity. Our aim was to evaluate and compare the performance of two high shear systems (the O’Brien filter test and the PFA-100 device) in the screening and diagnosis of vWD. Thirty patients (n=13 type 1 with mild symptoms, n = 9 type 1 with severe symptoms, n = 2 type 2A, n = 3 type 2B and n = 3 type 3 vWD) and twenty controls were investigated. In mild vWD the platelet retention in the second phase of the filter test with citrated blood showed the highest sensitivity (91.6%). The sensitivity of the PFA-100 method with collagen-epinephrine cartridges in this group was 76.9%, while the bleeding time was prolonged only in 15.4% of the cases. In severe type 1, in type 2A and type 3 all functional tests reflected the bleeding tendency of the patients. In type 2B disease the bleeding time was prolonged only when the patient was thrombocytopenic, but both high shear systems revealed the disease independently of the presence of thrombocytopenia. The overall sensitivity of the bleeding time determination was 50% compared to the 80-90% sensitivity of the O’Brien filter test and the PFA-100 system. The sensitivity values of the filter test and the PFA-100 device with collagen-epinephrine cartridges were in the same range, but the collagen-ADP cartridges showed a lower (65.5%) sensitivity, though the results were specific and had high positive predictive value. We conclude that both high shear systems are suitable for the screening of vWD, and that they are superior to the traditional bleeding time determination in case of mild disease or type 2B vWD.

Emergency care of patients receiving non-vitamin K antagonist oral anticoagulants

Non-vitamin K antagonist oral anticoagulants (NOACs), which inhibit thrombin (dabigatran) and factor Xa (rivaroxaban, apixaban, edoxaban) have been introduced in several clinical indications. Although NOACs have a favourable benefit-risk profile and can be used without routine laboratory monitoring, they are associated-as any anticoagulant-with a risk of bleeding. In addition, treatment may need to be interrupted in patients who need surgery or other procedures. The objective of this article, developed by a multidisciplinary panel of experts in thrombosis and haemostasis, is to provide an update on the management of NOAC-treated patients who experience a bleeding episode or require an urgent procedure. Recent advances in the development of targeted reversal agents are expected to help streamline the management of NOAC-treated patients in whom rapid reversal of anticoagulation is required.

Edoxaban for treatment of venous thromboembolism in patients with cancer

Direct oral anticoagulants may be effective and safe for treatment of venous thromboembolism (VTE) in cancer patients, but they have not been compared with low-molecular-weight heparin (LMWH), the current recommended treatment for these patients. The Hokusai VTE-cancer study is a randomised, open-label, clinical trial to evaluate whether edoxaban, an oral factor Xa inhibitor, is non-inferior to LMWH for treatment of VTE in patients with cancer. We present the rationale and some design features of the study. One such feature is the composite primary outcome of recurrent VTE and major bleeding during a 12-month study period. These two complications occur frequently in cancer patients receiving anticoagulant treatment and have a significant impact. The evaluation beyond six months will fill the current gap in the evidence base for the long-term treatment of these patients. Based on the observation that the risk of recurrent VTE in patients with active cancer is similar to that in those with a history of cancer, the Hokusai VTE-cancer study will enrol patients if whose cancer was diagnosed within the past two years. In addition, patients with incidental VTE are eligible because their risk of recurrent VTE is similar to that in patients with symptomatic disease. The unique design features of the Hokusai VTE-cancer study should lead to enrolment of a broad spectrum of cancer patients with VTE who could benefit from oral anticoagulant treatment.

Clinical impact and course of major bleeding with edoxaban versus vitamin K antagonists

Edoxaban is a once-daily direct oral anticoagulant (DOAC). The Hokusai-VTE study revealed that, after initial treatment with heparin, edoxaban was non-inferior to and safer than vitamin K antagonists (VKA) in the prevention of recurrent deep-vein thrombosis and pulmonary embolism. This is the first report on the clinical relevance and management of bleeding events with edoxaban. All major bleeding events were classified blindly by three study-independent adjudicators. Predefined criteria were used to classify severity of clinical presentation and, separately, the clinical course and outcome into four categories. Major bleeding occurred in 56 patients treated with edoxaban and 65 patients treated with VKA. The severest categories (3 or 4) of the clinical presentation were assigned to 46 % of the major bleeding episodes in edoxaban recipients versus 58 % of the major bleeds in VKA recipients (odds ratio [OR] 0.62, 95 % confidence interval [CI] 0.30–1.27, p = 0.19). Clinical course was classified as severe (category 3 or 4) in 23 % of the edoxaban and 29 % of the VKA associated bleeds (OR 0.73, 95 % CI 0.32–1.66, p = 0.46). In conclusion, edoxaban associated major bleeding events have a comparable clinical presentation and course to major bleeds with VKA in patients treated for venous thromboembolism in the Hokusai-VTE study. These results may assure physicians that it is safe to prescribe this medication. If a major bleeding during edoxaban treatment occurs, its clinical presentation and clinical course are not worse than in VKA-treated patients.

Edoxaban for venous thromboembolism in patients with cancer: results from a non-inferiority subgroup analysis of the Hokusai-VTE randomised, double-blind, double-dummy trial

BACKGROUND

Venous thromboembolism occurs commonly in patients with cancer. Direct oral anticoagulants are non-inferior to conventional anticoagulants for the treatment of venous thromboembolism. We hypothesised that edoxaban, a direct oral inhibitor of activated clotting factor Xa, might be more suitable than conventional anticoagulants in the management of cancer-associated venous thromboembolism. The aim of this study was to assess the efficacy and safety of edoxaban compared with warfarin in a subgroup of patients with cancer enrolled in the Hokusai-VTE trial.

METHODS

We did a prespecified subgroup analysis in August, 2013, and a post-hoc analysis of non-inferiority and safety in March, 2016, of the patients with cancer enrolled in the randomised, double-blind, double-dummy, multicentre, Hokusai-VTE trial done between Jan 28, 2010, and Oct 31, 2012. In this study, patients aged at least 18 years with acute symptomatic deep-vein thrombosis or acute symptomatic pulmonary embolism (with or without deep-vein thrombosis) were assigned to receive edoxaban 60 mg once per day (or 30 mg once per day for patients with a creatinine clearance of 30-50 mL/min, bodyweight <60 kg, or who were receiving concomitant treatment with the P-glycoprotein inhibitors quinidine or verapamil) or warfarin (dose adjusted to maintain the international normalised ratio between 2·0 and 3·0) or placebos for either group for at least 3 months up to 12 months. All patients received initial therapy with open-label enoxaparin or unfractionated heparin for at least 5 days. Edoxoban (or placebo) was started after discontinuation of initial heparin; warfarin (or placebo) started concurrently with the study regimen of heparin. In our analysis we examined data for a subgroup of these patients who had a history of cancer or who had been categorised as having active cancer by the study physician at the time of enrolment. Additionally, all patients with a history of cancer were reviewed post hoc and categorised according to the presence or absence of active cancer. The primary efficacy outcome was the proportion of these patients with symptomatic recurrent venous thromboembolism during the 12-month study period, analysed in the modified intention-to-treat population, with an upper limit of the CI for the hazard ratio (HR) of 1·5. The principal safety outcome was the proportion of patients who had clinically relevant bleeding in the population of patients who received at least one dose of the study drug. This study is registered with ClinicalTrials.gov, number NCT00986154.

FINDINGS

Of 771 patients with cancer enrolled in the trial, 378 were assigned to edoxaban and 393 to warfarin. Recurrent venous thromboembolism occurred in 14 (4%) of 378 patients given edoxaban and in 28 (7%) of 393 patients given warfarin (hazard ratio [HR] 0·53, 95% CI 0·28-1·00; p=0·0007). The upper limit of this 95% CI did not exceed the non-inferiority margin of 1·5 that was prespecified for the trial. Clinically relevant bleeding (major or non-major) occurred in 47 (12%) of 378 patients who received edoxaban and in 74 (19%) of 393 patients who received warfarin; HR for clinically relevant bleeding 0·64, 95% CI 0·45-0·92; p=0·017. Major bleeding occurred in ten (3%) of 378 patients with a history of cancer who received edoxaban and in 13 (3%) of 393 who received warfarin (HR 0·80, 95% CI 0·35-1·83).

INTERPRETATION

Edoxaban might be as effective as warfarin for the treatment of patients with cancer with venous thromboembolism, and with less clinically relevant bleeding. Additional clinical trials of edoxaban versus low-molecular-weight heparin for the treatment of venous thromboembolism in patients with cancer are warranted.

FUNDING

Daiichi Sankyo.

Founder effect is responsible for the p.Leu131Phe heparin-binding-site antithrombin mutation common in Hungary: phenotype analysis in a large cohort

BACKGROUND

Antithrombin (AT) is a key regulator of the coagulation. In type II deficiency, the heparin-binding-site defect (type II HBS) is considered to be relatively low thrombosis risk.

OBJECTIVES

Our aims were to search for SERPINC1 mutation(s) and to describe the clinical and laboratory phenotype of a large number of AT Budapest3 (ATBp3, p.Leu131Phe) carriers and confirm the presence of a founder effect.

PATIENTS/METHODS

AT-deficient patients were recruited and carriers of ATBp3, n = 102 (63 families) were selected. To investigate the founder effect, eight intragenic single nucleotide polymorphisms, a 5'-length dimorphism, and five microsatellite markers were detected. Clinical and laboratory data of the patients were collected and analyzed.

RESULTS

In AT deficiency, 16 different causative mutations were found, and the great majority of patients were of type II HBS subtype. Most of them (n = 102/118, 86.5%) carried the ATBp3 mutation. The ATBp3 mutant allele was associated with one single haplotype, while different haplotypes were detected in the case of normal allele. The anti-factor Xa-based AT activity assay that we used could detect all ATBp3 patients with high sensitivity in our cohort. ATBp3 homozygosity (n = 26) was associated with thrombosis at a young age and conferred a high thrombotic risk. Half of the heterozygotes (n = 41/76, 53.9%) also had venous and/or arterial thrombosis, and pregnancy complications were also recorded.

CONCLUSION

In Hungary, the founder mutation, ATBp3, is the most common AT deficiency. Our study is the first in which the clinical characterization of ATBp3 mutation was executed in a large population.

Direct Thrombin Inhibitors and Factor Xa Inhibitors Can Influence the Diluted Prothrombin Time Used as the Initial Screen for Lupus Anticoagulant

Context.—Lupus anticoagulant (LA) is a heterogeneous group of antiphospholipid antibodies. Among others, diluted prothrombin time (dPT) is a sensitive screening test for LA; however, the interpretation of LA tests is difficult in patients treated with anticoagulants. The effect of different types of anticoagulants on the result of LA tests, particularly on dPT, has not been studied extensively.

Objective.—To determine whether the direct thrombin inhibitors lepirudin and argatroban and the predominantly factor Xa inhibitors enoxaparin, danaparoid, and fondaparinux could interfere with LA screening based on dPT.

Design.—Each drug was added to normal and LA-positive plasmas in clinically relevant concentrations. Each sample was tested for dPT. Samples with factor Xa inhibitors were investigated before and after addition of heparinase. Mixing and confirmatory tests for LA were not performed.

Results.—In the presence of lepirudin or argatroban, dPT increased notably and the dPT ratio exceeded the cutoff value even at subtherapeutic concentrations resulting in false positivity. With increasing factor Xa inhibitor concentrations, a linear increase of dPT ratios and false-positive results were also demonstrated. Although heparinase could almost completely neutralize the anti-Xa effect of all investigated factor Xa inhibitors, dPT ratio returned to the basal level only in case of enoxaparin.

Conclusions.—Here we provide evidence that both the direct thrombin and indirect factor Xa inhibitors influence dPT assay for LA, causing false positivity. This should be considered when interpreting LA results during anticoagulant therapy. However, dPT seems to be a reliable test for LA screening under enoxaparin therapy after neutralization by heparinase.

Common large partial VWF gene deletion does not cause alloantibody formation in the Hungarian type 3 von Willebrand disease population

BACKGROUND

Type 3 von Willebrand disease (VWD) is an autosomal recessive bleeding disorder, characterized by virtually undetectable plasma von Willebrand factor (VWF) and consequently reduced plasma factor VIII levels. Genetic mutations responsible for type 3 VWD are very heterogeneous, scattered throughout the VWF gene and show high variability among different populations.

METHODS

Twenty-five severe VWD patients were studied by direct sequencing of the 51 coding exons of the VWF gene. The total number of VWD type 3 families in Hungary is 24, of which 23 were investigated.

RESULTS

Fifteen novel mutations were identified in 31 alleles, five being nonsense mutations (p.Q1238X, p.Q1898X, p.Q1931X, p.S2505X and p.S2568X), four small deletions and insertions resulting in frame shifts (c.1992insC, c.3622delT, c.5315insGA and c.7333delG), one a large partial deletion (delExon1-3) of the 5'-region, four candidate missense mutations (p.C35R, p.R81G, p.C295S, p.C623T) and one a candidate splice site mutation (c.1730-10C>A). Six previously described mutations were detected in 17 alleles, including the repeatedly found c.2435delC, p.R1659X and p.R1853X. Only one patient developed alloantibodies to VWF, carrying a homozygous c.3622delT.

CONCLUSION

We report the genetic background of the entire Hungarian type 3 VWD population. A large novel deletion, most probably due to a founder effect, seems to be unique to Hungarian type 3 VWD patients with high allele frequency. In contrast to previous reports, none of the five patients homozygous for the large partial deletion developed inhibitors to VWF. This discrepancy raises the possibility of selection bias in some of the reports.

Stem cell therapy: a promising and prospective approach in the treatment of patients with severe Buerger's disease

No effective blood-flow enhancement therapies are available for patients with severe peripheral arterial disease (SPAD), thus amputation remains the only option for relief of rest pain or gangrene. Autologous bone marrow-derived stem cell therapy (ABMSCT) is an emerging modality to induce angiogenesis from endothelial progenitors. A total of 5 patients with SPAD were treated by ABMSCT using isolated CD34+ cells with characterized phenotype administered by intramuscular injections. The follow-up before and 1, 3, 6, 9, and 12 months after ABMSCT was based on clinical (rest pain, walking distance without pain, nonhealing ulcers, ankle-brachial index [ABI]) and laboratory (angiography, duplex and laser ultrasonography, TcPO(2)) parameters. Significant improvement of pain and walking distance was observed in all patients. Nonhealing ulcers disappeared in 3 patients and became smaller and thinner in 1 patient. The average of ABI improved significantly on the treated limb but did not change on the contralateral limb. New collaterals were detected by angiography in 3 patients, but duplex ultrasonography detected improvement in one patient only. Laser ultrasonography showed a mild significant change, TcPO(2) values improved mainly on the foot. Severe adverse events were not observed. We conclude that ABMSCT with isolated CD34+ cells is safe, effective, and results in sustained clinical benefit for patients with SPAD.

Anti-factor V auto-antibody in the plasma and platelets of a patient with repeated gastrointestinal bleeding

Development of autoantibody against coagulation factor V (FV) is a rare clinical condition with hemorrhagic complications of varying severity. The aim of this study was to establish the pathomechanism of an acquired FV deficiency and characterize the FV inhibitor responsible for the clinical symptoms. A 78-year-old female was admitted to hospital with severe gastrointestinal bleeding. General clotting tests and determination of clotting factors were performed by standard methods. FV antigen and FV containing immune complexes were measured by ELISA. The FV molecule was investigated by Western blotting and by sequencing the f5 gene. The binding of patient's IgG to FV and activated FV (FVa) was demonstrated in an ELISA system and its effect on the procoagulant activity of FVa was tested in clotting tests and in a chromogenic prothrombinase assay. Localization of the epitope for the antibody was performed by blocking ELISA. FV activity was severely suppressed both in plasma and platelets. FV antigen levels were normal by ELISA using polyclonal anti-FV antibody or monoclonal antibody against the connecting region of FV, but depressed when HV1 monoclonal antibody against the C2 domain in the FV light-chain was used as capture antibody. The FV molecule was found intact. An IgG reacting with both FV and FVa was present in the patient's plasma and its binding to FV was inhibited by HV1 antibody. FV-containing immune complexes were detected in the patient's plasma and platelet lysate. The patient's IgG inhibited the procoagulant function of FVa. An anti-FV IgG was present in the patient's plasma and platelets. The autoantibody reacted with an epitope in the C2 domain of FV light chain and neutralized the procoagulant function of FVa.

[High-shear force-induced platelet aggregation in the screening and diagnosis of von Willebrand disease]

Von Willebrand's disease (vWD) is the most common congenital haemorrhagic diathesis, characterized by the quantitative or qualitative disorder of von Willebrand factor (vWF). A number of methods have been used for the diagnosis of the disease, and the bleeding time determination is widely accepted as a screening test in spite of its low sensitivity. Our aim was to evaluate and compare the performance of two high shear systems (the O'Brien filter test and the PFA-100 device) in the screening and diagnosis of vWD. Thirty patients (n = 13 type 1 with mild symptoms, n = 9 type 1 with severe symptoms, n = 2 type 2A, n = 3 type 2B and n = 3 type 3 vWD) and twenty controls were investigated. In mild vWD the platelet retention in the second phase of the filter test with citrated blood showed the highest sensitivity (91.6%). The sensitivity of the PFA-100 method with collagen-epinephrine cartridges in this group was 76.9%, while the bleeding time was prolonged only in 15.4% of the cases. In severe type 1, in type 2A and type 3 all functional tests reflected the bleeding tendency of the patients. In type 2B disease the bleeding time was prolonged only when the patient was thrombocytopenic, but both high shear systems revealed the disease independently of the presence of thrombocytopenia. The overall sensitivity of the bleeding time determination was 50% compared to the 80-90% sensitivity of the O'Brien filter test and the PFA-100 system. The sensitivity values of the filter test and the PFA-100 device with collagen-epinephrine cartridges were in the same range, but the collagen-ADP cartridges showed a lower (65.5%) sensitivity, though the results were specific and had high positive predictive value. We conclude that both high shear systems are suitable for the screening of vWD, and that they are superior to the traditional bleeding time determination in case of mild disease or type 2B vWD.

Comparison of the O'Brien filter test and the PFA-100 platelet analyzer in the laboratory diagnosis of von Willebrand's disease

Von Willebrand's disease (vWD) is the most common congenital haemorrhagic diathesis, characterized by the quantitative or qualitative disorder of von Willebrand factor (vWF). A number of methods have been used for the diagnosis of the disease, and the bleeding time determination is widely accepted as a screening test in spite of its low sensitivity. Our aim was to evaluate and compare the performance of two high shear systems (the O'Brien filter test and the PFA-100 device) in the screening and diagnosis of vWD. Thirty patients (n=13 type 1 with mild symptoms, n = 9 type 1 with severe symptoms, n = 2 type 2A, n = 3 type 2B and n = 3 type 3 vWD) and twenty controls were investigated. In mild vWD the platelet retention in the second phase of the filter test with citrated blood showed the highest sensitivity (91.6%). The sensitivity of the PFA-100 method with collagen-epinephrine cartridges in this group was 76.9%, while the bleeding time was prolonged only in 15.4% of the cases. In severe type 1, in type 2A and type 3 all functional tests reflected the bleeding tendency of the patients. In type 2B disease the bleeding time was prolonged only when the patient was thrombocytopenic, but both high shear systems revealed the disease independently of the presence of thrombocytopenia. The overall sensitivity of the bleeding time determination was 50% compared to the 80-90% sensitivity of the O'Brien filter test and the PFA-100 system. The sensitivity values of the filter test and the PFA-100 device with collagen-epinephrine cartridges were in the same range, but the collagen-ADP cartridges showed a lower (65.5%) sensitivity, though the results were specific and had high positive predictive value. We conclude that both high shear systems are suitable for the screening of vWD, and that they are superior to the traditional bleeding time determination in case of mild disease or type 2B vWD.

Acquired Bernard-Soulier syndrome: a case with necrotizing vasculitis and thrombosis

We describe a patient with positive antinuclear antibodies, polyclonal gammopathy and high level of circulating immunocomplexes, resulting in vascular purpura. In addition, the patient had a slightly prolonged bleeding time and an isolated defect of ristocetin-induced platelet aggregation (RIPA) in platelet-rich plasma (PRP). The patient's plasma also inhibited RIPA in normal PRP and in normal platelet suspension. The activity and multimeric structure of plasmatic von Willebrand factor showed no alteration. We could demonstrate an autoantibody against platelet membrane glycoprotein (GP) Ib, using an ELISA-type assay. These data suggest an acquired Bernard-Soulier syndrome. We suggest that the patient had an immunocomplex-mediated leukocytoclastic vasculitis accompanied by production of antinuclear autoantibodies as well as the presence of an autoantibody against GPIb. The titer of the anti-GPIb antibody, however, was too low to induce significant platelet-type bleeding tendency, only laboratory alterations were found. Moreover, in a later stage of her disease, she developed a severe necrotizing vasculitis which was followed by a deep venous thrombosis.

Use of a platelet filter test in patients with thrombocytosis

In the differential diagnosis of primary and secondary thrombocytosis platelet function tests may play an important role. We examined the applicability of a platelet filter test (shear-dependent platelet aggregation) as a tool, to differentiate primary thrombocytosis (cases with myeloproliferative disorders) from secondary (reactive) thrombocytosis. The test was carried out in 53 patients suffering from myeloproliferative disorders associated with primary thrombocytosis and in 21 patients with other diseases complicated by secondary thrombocytosis. Using citrate as anticoagulant, the sensitivity of the O'Brien's test proved to be 77.1%, and its specificity 94.4%. Using heparin as anticoagulant the sensitivity and specificity of the test were found to be also reliably high. Based on these studies we suggest the use of the O'Brien's filterometer as a screening test in the differential diagnosis in patients with elevated platelet count. In the case of normal results, the causes of reactive thrombocytosis should be clarified first, while with abnormal results, haematological examination of the patients should be performed.

[Clinical aspects of heparin induced thrombocytopenia]

Heparin induced thrombocytopenia has remained the major complication of therapy or prophylaxis with heparin. Although low molecular weight heparins seem to confer much lesser chance to induce thrombocytopenia, the danger is still considerable, and the fatal outcome is not rare. A lot of new data have been published about the origin, binding, physicochemical properties of the antibodies, the responsive platelet membrane receptors, and laboratory diagnosis in particular, however, many issues are still unresolved. The anticoagulant treatment of cases, in which heparin induced thrombocytopenia in associated with progressive, frequently arterial thrombosis still needs great skills, experience and the use of new generation antithrombotic agents. This review summarizes briefly the internationally accepted standard diagnostic and therapeutic protocols with heparin induced thrombocytopenia.

Safety of low-molecular-weight heparin in pregnancy: a systematic review

Unfractionated heparin (UFH) remains the anticoagulant of choice during pregnancy. Low-molecular-weight heparins (LMWH) are an attractive alternative to UFH due to their logistic advantages and their association with a lower incidence of osteoporosis and HIT. We reviewed all published clinical reports concerning the use of LMWH during pregnancy. In addition, participants of an international interest group contributed a cohort of pregnant women treated with LMWH. Pregnancies were divided into two groups; those with and those without maternal comorbid conditions. The number of adverse fetal outcomes and the occurrence of maternal complications were evaluated in the two groups. In the group of women with comorbid conditions (n = 290), 13.4% of the pregnancies were associated with an adverse fetal outcome. In contrast, in the group of women without comorbid conditions (n = 196), 3.1% were associated with an adverse outcome, which is comparable to that seen in the normal population. We conclude that LMWH appear to be a safe alternative to unfractionated heparin as an anticoagulant during pregnancy.

Safety of Low-Molecular-Weight Heparin in Pregnancy: A Systematic Review

Unfractionated heparin (UFH) remains the anticoagulant of choice during pregnancy. Low-molecular-weight heparins (LMWH) are an attractive alternative to UFH due to their logistic advantages and their association with a lower incidence of osteoporosis and HIT. We reviewed all published clinical reports concerning the use of LMWH during pregnancy. In addition, participants of an international interest group contributed a cohort of pregnant women treated with LMWH. Pregnancies were divided into two groups; those with and those without maternal comorbid conditions. The number of adverse fetal outcomes and the occurrence of maternal complications were evaluated in the two groups. In the group of women with comorbid conditions (n = 290), 13.4% of the pregnancies were associated with an adverse fetal outcome. In contrast, in the group of women without comorbid conditions (n = 196), 3.1% were associated with an adverse outcome, which is comparable to that seen in the normal population. We conclude that LMWH appear to be a safe alternative to unfractionated heparin as an anticoagulant during pregnancy.

[Thrombophilia, anticoagulant therapy and pregnancy]

Thromboembolic complications during pregnancy are the most common causes of maternal death. Here we report on thromboembolic prophylaxis of 60 pregnancies of 32 pregnant women with familial thrombophilia. Long-term Fraxiparine (Sanofi-Chinoin) as thromboprophylaxis was applied in 26 cases throughout pregnancy. UFH (Heparin-Ca inj.) was used in 11 cases, and there were 23 pregnancies without thromboembolic prophylaxis in our patient's case histories. Artificial abortions were not included in this paper. The ratio of successful pregnancies were: with Fraxiparine: 24/26 (92.3%), with UFH (Heparin-Ca): 8/11 (72.7%), without prophylaxis: 4/23 (17.4%). In the patient group treated with Fraxiparine there were no foetopathy, thrombocytopenia or bleeding complication. LMWH is recommended for pregnant women with familial thrombophilia. According to literature data and our own experiences the doses of LMWH in patients with familial thrombophilia, and -antiphospholipid syndrome, and -artificial heart value are suggested.

[The O'Brien filter test in the differential diagnosis of disorders with high-grade thrombocytosis]

In the differential diagnosis of primary and secondary thrombocytosis, platelet function test can be used. We have examined the possible role of O'Brien's filter test in the differentiation of primary and secondary thrombocytosis in 53 patients with myeloproliferative diseases with primary thrombocytosis and in 21 patients with other disorders complicated by secondary thrombocytosis. By using heparin as an anticoagulant, the sensitivity of O'Brien's filter test proved to be 75%, and it's specificity was 85.7%. In blood samples anticoagulated with citrate, the sensitivity was 100% and specificity 83.3%. Based on these studies we suggest the use of O'Brien's filterometer as a screening test in the differential diagnosis in patients with elevated (> 400 x 10(9)/L) platelet count. In case of normal results, the causes of reactive thrombocytosis should be cleared first, while with pathologic results, haematological examination of the patients should be performed.

[Fibrinogen as an independent cardiovascular risk factor and the question of treatment with fibrinogen-lowering drugs]

The atherosclerotic vascular disease is a progressive condition of multifactorial origin. Among cardiovascular risk factors alterations of lipid metabolism are of central role. But the haemostatic system, first of all the plasmatic fibrinogen is also highly implicated. Increased fibrinogen condition can be regarded as a strong and independent predictor of cardiovascular risk. Total cholesterol, LDL-cholesterol and plasma fibrinogen concentration as risk factors are compared. Fibrinogen lowering treatments are also summarized.

[Coumarin combined with low-dose acetylsalicylic acid in the prevention of thromboembolic complications in patients with mitral and aortic valve prostheses]

Authors studied the effect of coumarin, and its combination with low-dose (125 mg/day) acetylsalicylic acid in the prevention of thromboembolic complication during a 10-year period (average 4.7 years) in a randomized trial of 296 patients aged 18-60 year with tilting disc type prosthetic heart valve (159 mitral and 137 aortic) in sinus rhythm. In the group treated with coumarin (152 patients, 743.4 patient-years) 4 cases (2 of them fatal) of valve thrombosis, 12 cases of peripheral embolism and 9 cases (3 intracranial, 3 among them fatal) of major bleeding were observed; in the group treated with coumarin plus acetylsalicylic acid (144 patients, 638.7 patient-years) 2 cases (1 of them fatal) of valve thrombosis, 4 cases of peripheral embolism and 14 cases (3 of them fatal) of major bleeding were observed. In the case of valve thromboses the difference between the two groups was non-significant but still clinically remarkable; peripheral embolism occurred in significantly higher number (p < 0.05). There was no statistically significant difference of bleeding complications between the two groups. The results suggest that the combination of coumarin plus low-dose acetylsalicylic acid is more effective in the prevention of thromboembolic complications in patients with mitral and aortic prosthetic heart valve than coumarin alone; the danger of bleeding complications seems to be acceptable with adequate control.

[Fibrinolysis and vascular diseases]

A wide array of in vitro fibrinolysis tests had been performed for a long period, suggesting defective fibrinolysis, mainly impaired tPA response and reserve as major, frequent abnormality, predecessor or causative factor of venous thromboembolism. However, these abnormalities were troublesome to reproduce, and more recently fibrinolytic activators and inhibitors received growing attention as rather atherogenic and less thrombogenic risk factors. Even if it is still not settled, lipoprotein(a) may interfere with fibrinolysis, and seems to carry atherogenic risk, too. The genetic polymorphism of fibrinogen, plasminogen, PAI-1 and some other compounds modifying circulating fibrinogen levels are also discussed in this review.

Coumarin-induced skin necrosis following heparin-induced thrombocytopenia and thrombosis. A case report

A severe thrombotic thrombocytopenic status, induced by heparin in a sixty-nine-year-old woman undergoing total hip joint arthroplasty, was treated by switching the anticoagulant therapy to coumarin, which induced skin necrosis. There appeared to be a possible causal relation between the severe immune reaction to heparin and the condition that predisposed to skin necrosis in the presence of coumarin. In patients who express a strong immune response to heparin, a different anticoagulant approach other than use of coumarin congeners appears to be justified.

Studies of the platelet filter test (shear dependent platelet aggregation) in patients with uncommon haemorrhagic disorders

Platelets of anticoagulated whole blood forced at 40 mmHg through a fine filter are activated, aggregated and retained, so block the filter (platelet filter test, O'Brien JR, Salmon GP. Blood 1987; 1354-1361). Our clinical experiences with this simple and quick haemostasis test are summarized. Patients were investigated with different types of vWD (type-1 = 35, type-2A = 7, type-2B = 7, type-3 = 1), Glanzmann's thrombasthenia, congenital deficiency of cyclo-oxygenase, acquired Bernard-Soulier syndrome, FXII-, FXIII-deficiency and a control group. The cumulative drop count and the platelet retention were carefully measured during two phases of the filter test. Platelet count, bleeding time, vWF:Ag and vWF:Rcof activity were measured along with the platelet filter test. The filter was not blocked and the platelet retention was abnormally low in all patients with thrombasthenia, type-2a, type-2B, type-3 vWD. Treatment with 1-desamino-8-D-arginine-vasopressin (DDAVP) caused enhanced platelet retention in 16 patients with type-1 vWD. The test is simple, quick and cheap, has good reproducibility, and may be useful in clinical haemostasis laboratories for examination of high shear induced platelet functions.

[Low-molecular-weight heparin in the prevention of thromboembolism in pregnant thrombophilic patients]

Prophylaxis of thromboembolism with low molecular weight heparin (LMWH) may offer some advantages over unfractionated heparin during pregnancy. Controlled studies with LMWH for thromboprophylaxis in pregnancy are failing, although according to some recent studies LMWH did not cross the placental barrier. LMWH as thromboprophylactic agent was used in three young pregnant women with familial thrombophilia (two with PC one with AT-III deficiency). According to the bodyweight of patients the applied doses of LMWH were 5,000-10,000 ICU once daily. Laboratory control (determination of anti-FXa activity in plasma samples) was made monthly. The three pregnancies were uneventful, thromboembolic or haemorrhagic complications did not develop. Newborns were healthy, with no coincide of disturbances of haemostasis. The LMWH-demand is certainly increased at the late period of pregnancy. LMWH as thromboprophylaxis is recommended for pregnants with familial thrombophilia. The necessary dose of Fraxiparine may be 70 ICU/kg/day in the first and 100 ICU/kg/day in the second half of pregnancy.

Promotion of the crosslinking of fibrin and alpha 2-antiplasmin by platelets

Factor XIII (FXIII) is of high importance in the regulation of fibrinolysis. It crosslinks alpha 2-antiplasmin (alpha 2AP) and fibrin and by this way protects fibrin from the prompt elimination by plasmin. Although FXIII of platelets has been implicated in this protective mechanism, the role of platelets and platelet FXIII in the crosslinking process is far from being elucidated. As demonstrated by SDS PAGE and by immunoblotting for alpha 2AP, intact normal platelets resuspended in FXIII-free plasma or FXIII-free fibrinogen solution catalyzed the crosslinking of fibrin chains and also the crosslinking of alpha 2AP to fibrin alpha-chains. With FXIII-deficient platelets no crosslinking reaction could be observed indicating that the crosslinking with normal platelets was, indeed, due to platelet FXIII and not to another, putative platelet transglutaminase. However, the crosslinking of alpha 2AP to fibrin induced by the FXIII of intact platelets resuspended in FXIII-free plasma was considerably less extensive than the crosslinking carried out by the FXIII of normal plasma in the presence of FXIII-free platelets. Furthermore, the replacement of FXIII-free platelets by normal platelets in normal FXIII-containing plasma resulted in little, if any, difference in the crosslinking process. When crosslinking was induced by highly purified plasma FXIII the presence of intact FXIII-free platelets significantly accelerated the formation of alpha-chain polymers as well as the incorporation of alpha 2AP-fibrin alpha-chain hetero-dimer into these polymers. The results indicate that, in physiological conditions, platelet FXIII plays only a minor role in the crosslinking of alpha 2AP and fibrin; however, platelets, independently of their FXIII content, promote the crosslinking reaction by providing a catalytic surface on which the formation of highly crosslinked fibrin polymers is accelerated.

[Syncumar-induced necrosis following heparin-induced thrombocytopenia and thrombosis]

The authors describe the combined occurrence of heparin-induced thrombocytopenia and cumarin-induced skin necrosis, a rare condition that has not yet been reported in Hungary. The 69-year-old woman had received prophylactic heparin treatment prior to total hip arthroplasty. The first complication that the anticoagulant therapy brought about was serious thrombocytopenia paradoxically associated not with bleeding but with deep vein thrombosis. The latter necessitated coumarin therapy which resulted in severe skin necrosis.

Cyclic relapses of thrombotic thrombocytopenic purpura

A 24-year-old male patient was first observed with full-blown acute thrombotic thrombocytopenic purpura in 1991. Complete remission was achieved with plasma and plasmapheresis therapy, but in spite of continuous corticosteroid and aspirin administration, thrombocytopenic (megakaryocytic) relapses were observed every 26-30 days. Splenectomy and danazol failed to prevent the recurrence of the disease. Surprisingly, cyclosporin A (5 mg/kg/day) administration resulted in a complete transitional remission, but after dose reduction a less regular pattern of repeated milder recurrences was observed. Cryopreserved plasma, obtained from the patient during remission also proved to be effective in treating the last two thrombocytopenic episodes.