Silmara Aparecida De Lima Montalvão

Microparticles in deep venous thrombosis, antiphospholipid syndrome and Factor V Leiden

Microparticles (MPs) are blebs released from cellular surfaces during activation/apoptosis. They are procoagulant, pro-inflammatory and could contribute to pathogenesis of deep venous thrombosis (DVT). This study compared the number, cellular origin and procoagulant activity of MPs on DVT patients in different clinical situations: at diagnosis (n = 9, 5F/4M; mean age = 41.11), 1-3 years after warfarin withdrawal (n = 10, 7F/3M; mean age = 32.90), associated to antiphospholipid syndrome (APS; n = 11, 9F/2M; mean age = 33.82), or asymptomatic carriers of Factor V Leiden (FVL; n = 7, 7F/0M; mean age = 34.00) vs healthy controls (CTR). The quantification and characterization were performed by flow cytometry using CD235, CD61, CD45, CD31, CD14, CD45, anti-TF and Annexin V. The plasmatic procoagulant activity was investigated by prothrombin fragment 1 + 2 (F1 + 2) determination. The MPs procoagulant activity was analyzed by D-dimer (DD2) and Thrombin Generation Test (TGT) on a healthy pool of plasmas adjusted or not by their number (10,000 MPs). The MPs percentages were not different between the groups, but absolute number was increased in patients 1-3 years after warfarin withdrawal vs CTR (P = 0.02). There was no difference of the MPs cellular origin comparing patients to controls. TGT using 10,000 MPs was lower on these patients (P = 0.01). APS patients showed a reduction of plasmatic procoagulant activity (P = 0.004), but they were under warfarin therapy. DD2 in the presence of MPs, independently of its number, was higher in patients with DVT at diagnosis (P < 0.0001). MPs of patients with spontaneous DVT at diagnosis can promote coagulation activation demonstrated by increased DD2. Even the increased MPs from patients 1-3 years after thrombotic episode generated lower amount of thrombin, they can have a protective effect by activation of Protein C anticoagulant pathway.

Severe Post-thrombotic Syndrome is Associated With Higher Levels of Factor VIII

Increased levels of factor VIII (FVIII) are a prevalent and independent risk factor for deep venous thrombosis (DVT). After a median of 10 years of the first DVT, we evaluated FVIII coagulation levels in 55 patients with DVT of the lower limbs and previous high levels of FVIII and in 74 controls. Subsequently, we analyzed the presence of post-thrombotic syndrome (PTS) in patients and its relationship with FVIII levels. After a median of 10 years of the first DVT, the FVIII levels were still significantly higher in patients when compared to controls (P < .001). Patients with severe PTS showed increased levels of FVIII when compared to patients with moderate or absent PTS (P < .001). We demonstrated a persistent increase in FVIII levels in a subset of patients with DVT, but in a lower magnitude after 10 years of the first DVT episode. Moreover, we observed a significant association between increased FVIII levels and severe PTS.

Impairment of thrombin generation in the early phases of the host response of sepsis

PURPOSE The purpose was to investigate the presence of hypercoagulability in the very early phase of the host response to an infection in the clinical course of sepsis and septic shock. MATERIAL AND METHODS Twenty-four patients with chemotherapy-associated febrile neutropenia were evaluated at baseline, at the time of fever onset, and 48 hours thereafter using the thrombin generation test, a more physiological and global assay of hemostasis. RESULTS The rate of thrombin generation was decreased and no signals of systemic hypercoagulability could be observed during the first 48 hours of sepsis. Moreover, patients that evolved to septic shock presented a more significant impairment in thrombin generation than those with noncomplicated sepsis. CONCLUSIONS Patients with sepsis and febrile neutropenia present an impairment in thrombin generation from very early stages of their disease course. These results suggest that the procoagulant in vitro alterations described during sepsis do not necessarily translate into a clinically relevant systemic hypercoagulable state. These findings could help explain why treatment with systemic anticoagulants did not translate to clinical benefits in human sepsis and highlight the need for a better understanding of the hemostatic alterations in sepsis before new treatments targeting coagulation activation are developed.

Heat treatment of samples improve the performance of the Nijmegen-Bethesda assay in hemophilia A patients undergoing immune tolerance induction.

Nijmegen-Bethesda assay is the gold standard to assess inhibitory antibodies against factor (F) VIII. This method has some limitations, including high coefficient of variation and possible interference of residual endogenous or exogenous factor VIII. Heat-treatment of samples at 56 °C for 30 min could be a strategy to improve the sensitivity of this test. The aim of this study was to compare inhibitor quantification in hemophilia patients with and without inhibitor performed in previously heated and non-heated samples. A total of 109 analyses from 46 patients with severe hemophilia A were performed. Patients were divided into three groups: 20 patients with no history of inhibitor, recently and not recently exposed to FVIII (group I), 21 patients with history of inhibitor not exposed to FVIII (group II), and 5 patients (68 samples) undergoing an immune tolerance induction (ITI) protocol (group III). For patients with no history of inhibitor, heat-treatment did not modify the results (p=0.24). However, differences in inhibitor levels between heated and non-heated samples were observed in patients with history of inhibitor (group II, p<0.05) and in patients in ITI (group III, p<0.001). In 11 samples, inhibitor quantification shifted from negative to positive. Additionally, a longitudinal evaluation of each ITI patient showed similar trend line for the results of heated and non-heated samples. In this study, we demonstrated that heating samples increase sensitivity of Nijmegen-Bethesda assay, with no shift from negative to positive results in patients with no history of inhibitor. Furthermore, this procedure has an important role to patients undergoing an ITI protocol.

Simultaneous bleeding and thrombosis in superwarfarin poisoning.

Superwarfarin poisoning causes a severe acquired coagulation disorder that, despite its frequency, severity and specific therapeutic implications, still goes largely unrecognized by physicians. Hematologists are often called to evaluate these patients, but unawareness of the specificities of the problem often precludes adequate diagnosis and treatment. Superwarfarin poisoning differs from coumarin overdose in that the former is resistant to reversal with standard doses of vitamin K, and that anticoagulant effects can last for weeks after drug discontinuation. Here we report a case of superwarfarin poisoning with a previously unreported clinical presentation, inwhich diffuse bleeding and venous thrombosis were simulta-

Long-term prospective study of recurrent venous thromboembolism in a Hispanic population.

The aim of this study was to assess the incidence and risk factors for recurrent venous thromboembolism (VTE) in a Hispanic population. We prospectively followed 343 patients after a first episode of objectively proven VTE. We excluded all patients with VTE at unusual sites, older than 70 years old, with neoplasia, liver or renal chronic disease and antiphospholipid syndrome. Predictors for recurrence were evaluated by Cox model. The probability of recurrent VTE was estimated by the method of Kaplan–Meier. The cumulative probability of recurrent VTE was 19.1% in 5 years and 30.0% in 10 years. Male sex [relative risk (RR) 1.7, 95% confidence interval (CI) 1.0–2.8], spontaneous first VTE (RR 2.9, 95% CI 1.7–5.0) and FII G20210A mutation (RR 4.2, 95% CI 1.9–9.4) were independent risk factors for recurrent VTE. The fibrinogen, coagulation factors VIII, IX, X and XI were measured in 200 patients and were not associated to thrombotic recurrence risk. This study indicates that the incidence of recurrent VTE is high in Hispanics and depends on clinical and laboratory findings. In this population, FII G20210A mutation may represent a specific risk factor for recurrence. The inclusion of different ethnic populations in epidemiological studies of VTE as well as new approaches to the management of anticoagulation therapy in Hispanics is warranted.

Effect of the injectable contraceptive depot‐medroxyprogesterone acetate on coagulation parameters in new users

The aim of this study was to assess the effects of the injectable depot‐medroxyprogesterone acetate (DMPA) contraceptive on selected blood coagulation parameters in young, healthy new users.

Laboratory evaluation of patients with undiagnosed bleeding disorders.

The evaluation of patients with a bleeding tendency represents a challenge as the routinely available tests for evaluating bleeding disorders are limited, complicating the laboratory determination of the clinically observed bleeding tendency. As a result, some bleeding disorders remain undiagnosed. The aim of the study was to evaluate whether global coagulation tests would contribute to the laboratory analysis of patients with undiagnosed bleeding disorders. Patients were evaluated for coagulation and fibrinolysis activities by thrombin generation test and euglobulin lysis time. In addition, plasma activity of factor XIII, plasminogen, &agr;-2 antiplasmin, plasminogen activator inhibitor-1, and thrombin-activatable fibrinolysis inhibitor was also obtained. Forty-five patients were included. Eight per cent presented a mild bleeding disorder and 20% a moderate bleeding disorder. The thrombin generation test results were similar between patients and controls. Euglobulin lysis time results, however, were lower in patients than in controls, both before (median 175 vs. 250 min, respectively; P = 0.003) and after (median 145 vs. 115 min, respectively; P ⩽ 0.001) arm constriction, suggesting that they were experiencing hyperfibrinolysis. Interestingly, patients’ median thrombin-activatable fibrinolysis inhibitor activity was higher than in controls (21.2 vs. 19.46 &mgr;g/ml; P = 0.016). However, plasminogen, &agr;-2 antiplasmin, plasminogen activator inhibitor-1, and factor XIII activities did not differ between the groups. Global coagulation and fibrinolysis tests proved to be limited in detecting the hemostatic disorders in some patients with a relevant bleeding tendency and may not be adequate to address their bleeding risk. Bleeding scores are currently the available medical approach for the evaluation of these patients.

Clinical implications of the detection of antibodies directed against domain 1 of β2-glycoprotein 1 in thrombotic antiphospholipid syndrome☆

INTRODUCTION Antibodies directed against domain 1 of β2 glycoprotein 1 (aβ2GP1-Dm1) have been involved in the immunopathogenesis of antiphospholipid syndrome (APS). However, the clinical relevance of aβ2GP1-Dm1 in thrombotic APS has not yet been fully explored. OBJECTIVES To determine the frequency of aβ2GP1-Dm1 in a cohort of patients with thrombotic APS, and to evaluate whether testing for aβ2GP1-Dm1 could have a clinical impact upon the risk assessment of the disease. METHODS Patients were tested for aβ2GP1-Dm1 antibodies by chemiluminescence (BioFlash/AcuStar®, ES). The presence of aβ2GP1-Dm1 was evaluated in different clinical presentations of the disease. RESULTS Eight-four patients with a history of venous or arterial thrombosis were included. Forty-five (54%) patients had aβ2GP1 antibodies and 40% of them were positive for aβ2GP1-Dm1. Levels of aβ2GP1-Dm1 were higher in patients with systemic autoimmune disease (AUC=0.665; 95% CI=0.544-0.786; P=0.01), positive antinuclear antibody (AUC=0.654; 95% CI=0.535-0.772; P=0.01), triple antiphospholipid antibody (aPL) positivity (AUC=0.680; 95% CI=0.534-0.825; P=0.02) and positive lupus anticoagulant (AUC=0.639; 95% CI=0.502-0.776; P=0.07). In this cohort, aβ2GP1-Dm1 antibodies were not associated with the site of the first thrombosis (OR=0,62, 95% CI=0.20-1.94, P=0.42), thrombosis recurrence (OR=1.0, 95% CI=0.37-2.71, P=1.0) or pregnancy morbidity (OR=1.5, 95% CI=0.33-7.34, P=0.58). In multivariate analysis, positivity for aβ2GP1-Dm1 antibodies was associated with the diagnosis of systemic autoimmune disease (OR=4.01, 95% CI=1.14-14.2; P=0.03) and triple aPL positivity (OR=3.59, 95% CI=0.87-14.85; P=0.07). CONCLUSIONS In the present cohort of thrombotic-APS patients, aβ2GP1-Dm1 antibodies were related to the diagnosis of systemic autoimmunity and complex serological profile of the disease, as triple aPL positivity and positive antinuclear antibody. Thus, our results suggest that testing for aβ2GP1-Dm1 antibodies may be useful for improving APS risk assessment.

Successful desensitization in a patient with Von Willebrand´s disease and anaphylaxis to factor VIII/VW

Background Von Willebrand s disease (VWD) is the most common congenital disorder of hemostasis, characterized by deficient or defective von Willebrand factor. Patients are treated by intravenous replacement of factor VIII/VW (FVIII/ VW) when needed, for prophylaxis before surgical procedures. Anaphylactic reactions to FVIII/VW are rare and desmopressin (DDAVP) can be used as an alternative.