Background The optimal anticoagulant regimen to prevent pregnancy-related venous thrombosis (VT) in women with antithrombin (AT) deficiency is unknown. Objectives This study aims to identify optimal doses of low-molecular-weight heparin (LMWH) to prevent pregnancy-related VT and to investigate if AT concentrate peripartum could reduce postpartum VT in women with AT deficiency. Methods This retrospective study includes 115 pregnancies in 57 women with subclassified AT deficiency treated with LMWH in Denmark, Norway, and Sweden (1991-2017). Results In pregnancies with high-risk AT deficiency, LMWH doses of <5000 IU/24 h, 5000 to 12 500 IU/24 h, and >12 500 IU/24 h revealed different VT risks (P = .02). The hazard ratios for VT were 1.0 (reference), 0.5 (95% CI [0.1, 2.3]), and 0 (95% CI [0, ∞]), correspondingly. Of the additional risk factors, only previous VT reached statistical significance. In 100 pregnancies with high-risk AT deficiency, 15 VTs occurred in contrast to none in the 15 pregnancies with low-/intermediate-risk AT deficiency. Six of the 12 antepartum VTs occurred before week 9. All had a prior VT, and 5 were hormone-associated. Of these 5, 1 had received a LMWH dose of 7500 IU/24 h and 3 had received a LMWH dose of 10 000 IU/24 h, respectively. AT concentrate, given peripartum in 66 of the 74 term pregnancies, resulted in 1 VT (1.5%). Without AT concentrate (8 pregnancies), 2 VTs occurred (25%; 95% CI [2, 61]). Peripartum hemorrhage (>1000 mL) occurred in 8 (11%) term pregnancies. Six had received therapeutic LMWH doses. Conclusion In high-risk AT deficiency pregnancies with previous VT, our results support prophylaxis with high prophylactic doses of LMWH from confirmed pregnancy. Hence, AT concentrate should be given peri-/postpartum.

Nature is always the best inspiration for basic research. A family with severe thrombosis and antithrombin deficiency, the strongest anticoagulant, carried a new mutation affecting the translation-start codon of SERPINC1, the gene encoding antithrombin. Expression of this variant in a eukaryotic cell system produced three different antithrombins. Two downstream methionines were used as alternative initiation codons, generating highly expressed small aglycosylated antithrombins with cytoplasmic localization. Wild-type antithrombin was generated by the use of the mutated AUU as initiation codon. Actually, any codon except for the three stop codons might be used to initiate translation in this strong Kozak context. We show unexpected consequences of natural mutations affecting translation-start codons. Downstream alternative initiation AUG codons may be used when the start codon is mutated, generating smaller molecules with potential different cell localization, biochemical features and unexplored consequences. Additionally, our data further support the use of other codons apart from AUG for initiation of translation in eukaryotes.

HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome is serious for the mother and the offspring. HELLP occurs in 0.2–0.8% of pregnancies and in 70–80% of cases it coexists with preeclampsia (PE). This review concerns the pathogenetic mechanisms of HELLP syndrome with an emphasis on differences between HELLP and early onset PE. The syndromes show a familial tendency. A previous HELLP pregnancy is associated with an increased risk of HELLP as well as PE in subsequent pregnancies, indicating related etiologies. No single world-wide genetic cause for excessive risk of HELLP or PE has been identified. Combinations of multiple gene variants, each with a moderate risk, with contributing effects of maternal and environmental factors, are probable etiological mechanisms. Immunological maladaptation is the most probable trigger of the insult to the invading trophoblast. This insult occurs early in the first trimester, as indicated by marker molecules in maternal blood. The levels of fetal messenger RNAs in maternal blood at gestational weeks 15–20 are significantly more abnormal in HELLP than in PE, suggesting that the insult is more extensive in HELLP. High levels of HLA-DR in maternal blood in women with HELLP may suggest a similarity to the rejection reaction. In third trimester placentas, gene derangement is more extensive in HELLP. Anti-angiogenic factors released into maternal blood induce the maternal syndromes. Maternal blood levels of anti-angiogenic sFlt1 are similar, but endoglin and Fas Ligand levels are possibly higher in HELLP than in PE. These factors trigger the vascular endothelium, resulting in an enhanced inflammatory response which is stronger in HELLP. Activated coagulation and complement, with high levels of activated leucocytes, inflammatory cytokines, TNF-α, and active von Willebrand factor, induce thrombotic microangiopathy with platelet–fibrin thrombi in microvessels. The angiopathy results in consumption of circulating platelets, causes hemolysis in affected microvessels and reduces portal blood flow in the liver. Placental Fas Ligand damages hepatocytes, resulting in periportal necrosis. In about one half of women with HELLP, activation of coagulation factors and platelets precipitates disseminated intravascular coagulation, which in a minority becomes uncompensated and contributes to life-threatening multiorgan failure.

Deficiencies of antithrombin (AT), protein C (PC) and protein S (PS), homozygous factor V Leiden (FVL) or prothrombin (FII) G20210A mutations and combined abnormalities confer a high risk of first venous thromboembolism (VTE), a significantly increased risk of recurrent VTE, and increased total morbidity in pregnancy. Screening for this high risk group is indicated in young patients with unprovoked VTE or with familial VTE. The heterozygous FVL and FII G20210A mutations confer moderately increased risk of a first VTE and a low risk of recurrent VTE. Screening for this low risk group is controversial and recommended on an individual basis only. The low risk types are absent in Asian and African populations. The Coagulation Inhibitor Potential (CIP) assay monitors fibrin formation and measures the inhibition of coagulation in presence of pentasaccharide and Protac. In a pilot study, CIP performed better than the Calibrated Automated Thrombin generation (CAT) and the ProC Global assays in discriminating 21 persons with high risk hereditary thrombophilia from healthy controls.

Introduction: After completed anticoagulant treatment for acute VTE, both the subsequent mortality and risk of recurrent VTE are high, probably related to the frequent presence of serious disease in these patients. The aim of the study was to determine survival and recurrence in selected patients with good life-expectancy, and to evaluate risk factors.Methods: The 323 patients were followed for median 7.4 years (range 4.1-11.9) after cessation of anticoagulation. Survival analysis and Cox-regression were used for univariate and multivariate analysis.Results: The cumulative incidence of survival after 5 years was 93.4%. Standardised mortality ratio was 1.42 for men and 1.28 for women. Patients without a transient risk factor prior to the index VTE were associated with higher risk of mortality compared to risk of mortality in patients with a transient risk factor (hazard ratio (HR) 2.81; 95% CI 1.40-5.62). Recurrence of VTE after 5 years was 19.0%. A persistent risk factor or a spontaneous VTE was associated with higher risk of recurrence compared to a transient risk factor (HR 2.39; 95% CI 1.44-3.95). Elevated D-dimer levels increased the risk, and immobilisation prior to the index VTE reduced the risk of recurrence. Sex, age and thrombophilia were not independent risk factors for recurrence.Conclusions: Despite a low mortality rate in this selected cohort, the recurrence rate and risk factors for recurrence were similar to findings reported in unselected populations. VTE unrelated to a transient risk factor was associated with increased mortality compared to mortality in patients with a transient risk factor. (C) 2011 Elsevier Ltd. All rights reserved.

Abstract Background The HELLP syndrome is a serious complication in pregnancy characterized by haemolysis, elevated liver enzymes and low platelet count occurring in 0.5 to 0.9% of all pregnancies and in 10–20% of cases with severe preeclampsia. The present review highlights occurrence, diagnosis, complications, surveillance, corticosteroid treatment, mode of delivery and risk of recurrence. Methods Clinical reports and reviews published between 2000 and 2008 were screened using Pub Med and Cochrane databases. Results and conclusion About 70% of the cases develop before delivery, the majority between the 27th and 37th gestational weeks; the remainder within 48 hours after delivery. The HELLP syndrome may be complete or incomplete. In the Tennessee Classification System diagnostic criteria for HELLP are haemolysis with increased LDH (> 600 U/L), AST (≥ 70 U/L), and platelets < 100·109/L. The Mississippi Triple-class HELLP System further classifies the disorder by the nadir platelet counts. The syndrome is a progressive condition and serious complications are frequent. Conservative treatment (≥ 48 hours) is controversial but may be considered in selected cases < 34 weeks' gestation. Delivery is indicated if the HELLP syndrome occurs after the 34th gestational week or the foetal and/or maternal conditions deteriorate. Vaginal delivery is preferable. If the cervix is unfavourable, it is reasonable to induce cervical ripening and then labour. In gestational ages between 24 and 34 weeks most authors prefer a single course of corticosteroid therapy for foetal lung maturation, either 2 doses of 12 mg betamethasone 24 hours apart or 6 mg or dexamethasone 12 hours apart before delivery. Standard corticosteroid treatment is, however, of uncertain clinical value in the maternal HELLP syndrome. High-dose treatment and repeated doses should be avoided for fear of long-term adverse effects on the foetal brain. Before 34 weeks' gestation, delivery should be performed if the maternal condition worsens or signs of intrauterine foetal distress occur. Blood pressure should be kept below 155/105 mmHg. Close surveillance of the mother should be continued for at least 48 hours after delivery.

introduction: Pregnancy increases the risk of mechanical heart valve (MHV) thrombosis. Warfarin is protective, but implies risks to the fetus. Unfractionated heparin (UFH) is less effective but does not harm the fetus. In general, anticoagulation is more stable and predictable with low molecular weight heparin (LMWH) than with UFH.Method: Retrospective study of 12 pregnancies with MHV; 6 in aortic, 4 in mitral, and 2 in both positions, treated with therapeutic doses of subcutaneous LMWH twice daily throughout pregnancy. Doses were adjusted using anti-Xa monitoring. The frequency of thrombo-embolism with various anticoagulation regimes was calculated based on a literature review.Results: Median LMWH dose was 15500 IU/24 h, range 10000-20000 IU/24 h: median dose 257 IU/kg/24 h. Median peak LMWH in blood plasma ranged 0.54-0.92 anti-Xa U/mL Thromboembolism developed in two women with aortic MHV despite LMWH levels in target range. One had systemic embolic episodes; in the other woman valve thrombosis was successfully thrombolysed. Both had initially received subtherapeutic doses. Thrombo-embolism was not observed in ten pregnancies treated as recommended. The pregnancies resulted in thirteen healthy babies; eight delivered by Cesarean section. Bleeding occurred in two women after Cesarean section due to preeclampsia.Conclusion: Treatment with adjusted therapeutic doses of LMWH was successful in 10 of 12 pregnancies,and was not associated with fetal complications. Thromboembolism occurred in two pregnancies, possibly attributed to subtherapeutic doses of LMWH during the initial 3 weeks. Compared to UFH prophylaxis, therapeutic doses of LMWH appears to be more efficacious. (c) 2009 Elsevier Ltd. All rights reserved.

The coagulation inhibitor potential (CIP) assay may detect major thrombophilia at a sensitivity of 100% and a specificity of 70–80%. Subnormal CIP might be associated with increased risk of thrombosis. This study compared the effect on CIP in plasma samples from postmenopausal women treated with four different regimens. Fibrin aggregation in plasma was monitored after activation with tissue factor. The effect of potentiated inhibition of coagulation was measured. Plasma samples from 202 healthy women randomly assigned to receive treatment for 12 weeks with conventional-dose or low-dose hormone therapy, raloxifene or tibolone were examined. Major thrombophilias were excluded. Compared with baseline, the median level in CIP was reduced by 64% in the conventional-dose group, by 38% in the low-dose group and by 31% in the raloxifene group, whereas for those treated with tibolone the median CIP increased by 9%. The median changes in CIP were significant for both hormone therapy groups (P < 0.0001) and for the raloxifene group (P = 0.003), but not for the tibolone group (P = 0.653). The 12 women with heterozygous factor V Leiden mutation had a significantly reduced median CIP level (P < 0.0001) at baseline. Hormone therapy and raloxifene, associated with venous thromboembolism, reduce the CIP. Tibolone does not reduce the CIP.

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Dear Sir, Filippatos et al. suggest that our relatively high target for warfarin therapy in our patients with mechanical heart valves, Internalized Normalized Ratio (INR) 2.5–4.2, might explain the high incidence of bleeding [1, 2]. They argue that when INR is out of this target range, bleedings could be more severe, and ask for the last INR values and the time intervals between last control and the bleeding episodes [1]. At the last visit prior to the bleeding, median INR was 3.5 and the two highest INR values were 4.0 and 6.0 in our patients. The time interval between this visit and the admittance with bleeding was 1– 2 weeks in four patients, 4–5 weeks in two patients, and excessive (about 8 weeks) in one patient. This patient had the highest INR, 7.5, at admittance. The median INR at admittance was 4.8, and above the therapeutic range in four patients. The mean interval between INR controls was 21 days in the total material, but 24 days in patients with bleeding (the difference was not statistically significant). For patients with venous thromboembolism or atrial fibrillation in our study, the therapeutic range was INR 2.0–3.0; few bleeding episodes occurred and the net gain was probably considerable [2]. These data thus confirm the suggestions of Filippatos et al. that both a relatively high therapeutic INR range, and long intervals between controls, appear to increase the risk of bleeding. Our study concerned patients monitored up to 1996 [2], and we have since then employed a lower therapeutic range in patients with mechanical heart valves (INR 2.5–3.5). Further, we recommend intervals of no more than 3–4 weeks between INR controls. We would like to add a short comment about comorbidity which is known to increase the risk of bleeding [3]. This was probably the case in five of the six mechanical valve patients with bleeding. In three patients with gastrointestinal bleeding, two bled from a malignant tumour and one patient was admitted twice with bleeding from angiodysplasia. One patient had infectious endocarditis with probable Disseminated Intravascular Coagulation (DIC), and one patient was admitted with a traumatic bleeding. As limitations to our study, we had mentioned that the subgroup of patients with mechanical heart valves was small [2]. As several larger studies had reported a much lower incidence of bleeding, we concluded that our results underestimated the value of warfarin therapy in these patients. We appreciate this opportunity of presenting additional data, confirming that both intense warfarin therapy and comorbidity may contribute to bleeding.

Knowledge of the net benefit of warfarin therapy in routine care is needed to define realistic management recommendations, but lack of randomized controls precludes conventional risk-benefit analysis.Assess risk and benefit of routine warfarin therapy in an anticoagulation clinic.Retrospective observational analysis.A total of 1435 outpatients on warfarin for a total of 1613 patient years, treated to prevent the target events recurrent venous thromboembolism (VTE) or myocardial infarction (MI), and stroke in patients with atrial fibrillation (AF) or mechanical heart valves.Major bleeding and thromboembolic (TE) events and all deaths.Expected annual target event rates without warfarin were from published data. Differences between combined major events observed with warfarin, and expected without warfarin were calculated.In the total material, annual rates were 3.0% major TE events, 1.1% major bleeding events, 0.12% fatal bleeding, and a benefit/risk ratio of 3.8. The net gain, expressed in reduced combined bleeding and target TE annual event rate, was 9.9% in secondary prophylaxis in AF, 4.4% in VTE patients, 2.7% in post-MI patients, 2.4% in primary prophylaxis in AF and 0.6 in patients with mechanical heart valves. The apparent benefit/risk ratio was 3.9 in VTE patients, 5.8 in AF patients and 1.1 in patients with mechanical heart valves.Net effects of prolonged warfarin therapy in patients with VTE and AF performed in an anticoagulation clinic have an acceptable risk/benefit ratio, comparable with what has been obtained in elective clinical trials.

Background Lupus anticoagulants prolong clotting times in phospholipid-dependent coagulation tests. Lupus Ratio assays are integrated tests for lupus anticoagulants that may be based on APTT, RVVT or dPT clotting times. If a patient is being treated with unfractionated heparin, however, the heparin prolong clotting times and the diagnosis of lupus anticoagulant is invalidated. Commercial assays may have heparin neutralising agents added to their reagents. However, the type and efficacy of the heparin neutralisation is often not documented. We wanted to test the influence and efficacy of heparin neutralisers in the Lupus Ratio assay. Methods Several heparin neutralisers were tested, and polybrene was chosen for further testing. Unfractionated heparin and/or polybrene were added to normal plasma and to plasma from patients with or without lupus anticoagulant and clotting times compared before and after the additions. Lupus anticoagulant-positive patients were given 5000 IU i.v. of unfractionated heparin and plasma was collected just before and five minutes after the injection. Lupus Ratios were calculated after polybrene was added to the postinjection samples. Results The Lupus Ratio became slightly lower when polybrene was added to plasma without heparin. Plasma heparinised in vitro and plasma from patients that had received heparin, both had Lupus Ratios nearly identical to the Lupus Ratios calculated before any additions. Conclusion By addition of polybrene to a final concentration of 7.9 μg/ml in test plasma, Lupus Ratio may be determined in lupus anticoagulant-negative as well as positive plasmas irrespective of the presence of heparin 0.0 – 1.3 U/ml.

Three global assays, the Calibrated Automated Thrombogram (CAT), the ProC Global (PCG), and the Coagulation Inhibitor Potential (CIP) were performed in frozen plasma samples from 24 normal controls and 24 patients with inherited thrombophilia. Six patients had inherited antithrombin (AT) deficiency; 18 patients had abnormalities in the protein C/S anticoagulant system (protein C deficiency (n=3), protein S deficiency (n=10), homozygous FV Leiden mutation (n=5)). Nine of these twenty four patients carried additionally the heterozygous FV Leiden mutation. All three assays separated the thrombophilia group and the control group (P=0.083 for CAT, P<0.0001 for the other two assays) but there was considerable overlap, particularly in the CAT assay. The CAT assay separated all plasma samples with AT deficiency but was less sensitive to abnormalities in the protein C/S system. In contrast, ProC Global was more sensitive to abnormalities in the protein C system than to AT deficiency. The CIP assay was approximately equally sensitive to defects in both systems. Receiver operator characteristic (ROC) curves confirmed that the ProC Global and the CIP assays performed better than the CAT assay (P=0.0179 and P=0.0003, respectively). With the CIP assay ROC analysis showed that with a sensitivity of 100% the specificity was 87.5%. With the PCG assay, optimal threshold resulted in both a sensitivity and a specificity of 79.2%. Although our material is relatively small, the data suggest that at a cut-off value with a specificity of >80%, the CIP assay should be evaluated as a screening test for severe thrombophilia.

INTRODUCTION:The Coagulation Inhibitor Potential (CIP) assay is a further development of the Overall Haemostatic Potential (OHP) by He et al. which monitors fibrin aggregation in plasma activated by thrombin, tissue-type plasminogen activator (t-PA) and CaCl2. CIP reflects the ability of enhanced coagulation inhibitors, antithrombin (AT) and protein C to counteract slow in vitro coagulation.MATERIALS AND METHODS:Plasma from 23 persons with different types of severe thrombophilic conditions were compared to normal controls. Pentasaccharide and Protac were added to enhance inhibition of coagulation. The relative effect of enhanced inhibition was calculated.RESULTS:The assay performed equally well with tissue factor (TF) and thrombin as triggers of coagulation (P<0.0001). Protac and rabbit thrombomodulin (TM) both demonstrated an anticoagulant effect, but only when pentasaccharide was present. Rabbit TM reduced fibrinolysis and Protac was used in the standard procedure. Pentasaccharide and Protac had a synergistic effect resulting in a clearly reduced coagulation in the normal controls, but less in persons with thrombophilia. Receiver operator characteristic (ROC) analysis indicated that at 100% sensitivity, specificity was 78% with and without t-PA.CONCLUSIONS:The improvement of the CIP by omitting t-PA allows a more rapid testing. There is a need for evaluating the CIP assay in larger patient groups.

We have previously shown that cancer patients with solid tumour disease have increased plasma levels of both the free and total forms of the coagulation inhibitor, tissue factor pathway inhibitor (TFPI), whereas patients with leukemia and related blood malignancies have levels within the normal range. We now report that also the median plasma levels of the Factor Xa (FXa)-TFPI complex were significantly higher in patients with solid tumours, compared to patients with haematological malignancy and healthy controls. There were significant positive correlations between the FXa-TFPI complex and total TFPI antigen (r=.47, P=.001) and TFPI activity (r=.33, P<.023). In plasma samples from patients with solid tumours, the ratio between the FXa-TFPI complex and free TFPI was 3.4 times higher than in patients with haematological malignancies. Increased levels of the FXa-TFPI complex in solid tumour disease may reflect both increased FXa generation and the increased TFPI concentration in the patients. It is speculated that high levels of the inhibitory FXa-TFPI complex in cancer patients may protect against microthrombosis and organ failure, which are relatively rare in cancer despite long-lasting hypercoagulation.

Oral anticoagulant treatment is used by a large number of patients for protection against thromboembolic complications. The main indications for prolonged therapy are presence of a mechanical heart valve, atrial fibrillation, and venous thromboembolism. Over time, many of these patients will require acute or elective surgery and, consequently, a consensus on the optimal perioperative management of anticoagulation in such patients is needed.