Intermediate-dose versus low-dose low-molecular-weight heparin in pregnant and post-partum women with a history of venous thromboembolism (Highlow study): an open-label, multicentre, randomised, controlled trial.

BACKGROUND: Pregnancy-related venous thromboembolism is a leading cause of maternal morbidity and mortality, and thromboprophylaxis is indicated in pregnant and post-partum women with a history of venous thromboembolism. The optimal dose of low-molecular-weight heparin to prevent recurrent venous thromboembolism in pregnancy and the post-partum period is uncertain. METHODS: In this open-label, randomised, controlled trial (Highlow), pregnant women with a history of venous thromboembolism were recruited from 70 hospitals in nine countries (the Netherlands, France, Ireland, Belgium, Norway, Denmark, Canada, the USA, and Russia). Women were eligible if they were aged 18 years or older with a history of objectively confirmed venous thromboembolism, and with a gestational age of 14 weeks or less. Eligible women were randomly assigned (1:1), before 14 weeks of gestational age, using a web-based system and permuted block randomisation (block size of six), stratified by centre, to either weight-adjusted intermediate-dose or fixed low-dose low-molecular-weight heparin subcutaneously once daily until 6 weeks post partum. The primary efficacy outcome was objectively confirmed venous thromboembolism (ie, deep-vein thrombosis, pulmonary embolism, or unusual site venous thrombosis), as determined by an independent central adjudication committee, in the intention-to-treat (ITT) population (ie, all women randomly assigned to treatment). The primary safety outcome was major bleeding which included antepartum, early post-partum (within 24 h after delivery), and late post-partum major bleeding (24 h or longer after delivery until 6 weeks post partum), assessed in all women who received at least one dose of assigned treatment and had a known end of treatment date. This study is registered with ClinicalTrials.gov, NCT01828697, and is now complete. FINDINGS: Between April 24, 2013, and Oct 31, 2020, 1339 pregnant women were screened for eligibility, of whom 1110 were randomly assigned to weight-adjusted intermediate-dose (n=555) or fixed low-dose (n=555) low-molecular-weight heparin (ITT population). Venous thromboembolism occurred in 11 (2%) of 555 women in the weight-adjusted intermediate-dose group and in 16 (3%) of 555 in the fixed low-dose group (relative risk [RR] 0·69 [95% CI 0·32-1·47]; p=0·33). Venous thromboembolism occurred antepartum in five (1%) women in the intermediate-dose group and in five (1%) women in the low-dose group, and post partum in six (1%) women and 11 (2%) women. On-treatment major bleeding in the safety population (N=1045) occurred in 23 (4%) of 520 women in the intermediate-dose group and in 20 (4%) of 525 in the low-dose group (RR 1·16 [95% CI 0·65-2·09]). INTERPRETATION: In women with a history of venous thromboembolism, weight-adjusted intermediate-dose low-molecular-weight heparin during the combined antepartum and post-partum periods was not associated with a lower risk of recurrence than fixed low-dose low-molecular-weight heparin. These results indicate that low-dose low-molecular-weight heparin for thromboprophylaxis during pregnancy is the appropriate dose for the prevention of pregnancy-related recurrent venous thromboembolism. FUNDING: French Ministry of Health, Health Research Board Ireland, GSK/Aspen, and Pfizer.

Clinical relevance of symptomatic superficial-vein thrombosis extension: lessons from the CALISTO study.

The clinical relevance of symptomatic extension of spontaneous, acute, symptomatic, lower-limb superficial-vein thrombosis (SVT) is debated. We performed a post hoc analysis of a double-blind trial comparing fondaparinux with placebo. The main study outcome was SVT extension by day 77, whether to ≤ 3 cm or > 3 cm from the sapheno-femoral junction (SFJ). All events were objectively confirmed and validated by an adjudication committee. With placebo (n = 1500), symptomatic SVT extension to ≤ 3 cm or > 3 cm from the SFJ occurred in 54 (3.6%) and 56 (3.7%) patients, respectively, inducing comparable medical resource consumption (eg, anticoagulant drugs and SFJ ligation); subsequent deep-vein thrombosis or pulmonary embolism occurred in 9.3% (5/54) and 8.9% (5/56) of patients, respectively. Fondaparinux was associated with lower incidences of SVT extension to ≤ 3 cm (0.3%; 5/1502; P < .001) and > 3 cm (0.8%; 12/1502; P < .001) from the SFJ and reduced related use of medical resources; no subsequent deep-vein thrombosis or pulmonary embolism was observed in fondaparinux patients. Thus, symptomatic extensions are common SVT complications and, whether or not reaching the SFJ, are associated with a significant risk of venous thromboembolic complications and medical resource consumption, all reduced by fondaparinux.

Onset of labor and use of analgesia in women using thromboprophylaxis with 2 doses of low-molecular-weight heparin: insights from the Highlow study.

BACKGROUND: Peripartum management of women using low-molecular-weight heparin (LMWH) varies widely. Minimum time intervals are required between LMWH injection and neuraxial procedure, and they differ by dose. OBJECTIVES: The objective of this study was to describe the onset of labor and use of analgesia in women using LMWH and to compare practices between intermediate-dose and low-dose LMWH. METHODS: In the Highlow study (NCT01828697), 1110 women were randomized to intermediate-dose or low-dose LMWH and were instructed to discontinue LMWH when labor commenced unplanned or 24 hours prior to planned delivery. The required time interval since last injection to receive a neuraxial procedure was ≥24 hours for intermediate-dose LMWH or ≥12 hours for low-dose LMWH. RESULTS: In total, 1018 women had an ongoing pregnancy for ≥24 weeks. Onset of labor was spontaneous in 198 of 509 (39%) women on intermediate-dose LMWH and in 246 of 509 (49%) on low-dose LMWH. With unplanned onset, a neuraxial procedure was performed in 37% on intermediate-dose and in 48% on low-dose LMWH (risk difference -11%, 95% CI -20% to -2%). Based on time interval, 61% on intermediate-dose and 82% on low-dose LMWH were eligible for a neuraxial procedure. With planned onset, 68% on intermediate-dose and 66% on low-dose LMWH received a neuraxial procedure, whereas 81% and 93%, respectively, were eligible for a neuraxial procedure (risk difference -13%, 95% CI -18% to -8%). CONCLUSION: With spontaneous onset of labor, neuraxial procedures were performed less often in women using intermediate-dose LMWH. Irrespective of onset, fewer women on intermediate-dose LMWH than those on low-dose LMWH were eligible for neuraxial procedures based on required time intervals since the last LMWH injection.

Inferior vena cava filters in pregnancy: Safe or sorry?

Background: Potential hazards of vena cava filters include migration, tilt, perforation, fracture, and in-filter thrombosis. Due to physiological changes during pregnancy, the incidence of these complications might be different in pregnant women. Aim: To evaluate the use and safety of inferior vena cava filters in both women who had an inferior vena cava filter inserted during pregnancy, and in women who became pregnant with an inferior vena cava filter in situ. Methods: We performed two searches in the literature using the keywords "vena cava filter", "pregnancy" and "obstetrics". Results: The literature search on women who had a filter inserted during pregnancy yielded 11 articles compiling data on 199 women. At least one filter complication was reported in 33/177 (19%) women and included in-filter thrombosis (n = 14), tilt (n = 6), migration (n = 5), perforation (n = 2), fracture (n = 3), misplacement (n = 1), air embolism (n = 1) and allergic reaction (n = 1). Two (1%) filter complications led to maternal deaths, of which at least one was directly associated with a filter insertion. Filter retrieval failed in 9/149 (6%) women. The search on women who became pregnant with a filter in situ resulted in data on 21 pregnancies in 14 women, of which one (6%) was complicated by uterine trauma, intraperitoneal hemorrhage and fetal death caused by perforation of the inferior vena cava filter. Conclusion: The risks of filter complications in pregnancy are comparable to the nonpregnant population, but could lead to fetal or maternal death. Therefore, only in limited situations such as extensive thrombosis with a contraindication for anticoagulants, inferior vena filters should be considered in pregnant women.

Low-molecular-weight heparin to prevent recurrent venous thromboembolism in pregnancy: Rationale and design of the Highlow study, a randomised trial of two doses.

BACKGROUND: Women with a history of venous thromboembolism (VTE) have a 2% to 10% absolute risk of VTE recurrence during subsequent pregnancies. Therefore, current guidelines recommend that all pregnant women with a history of VTE receive pharmacologic thromboprophylaxis. The optimal dose of low-molecular-weight heparin (LMWH) for thromboprophylaxis is unknown. In the Highlow study (NCT 01828697; www.highlowstudy.org), we compare a fixed low dose of LMWH with an intermediate dose of LMWH for the prevention of pregnancy-associated recurrent VTE. We present the rationale and design features of this study. METHODS: The Highlow study is an investigator-initiated, multicentre, international, open-label, randomised trial. Pregnant women with a history of VTE and an indication for ante- and postpartum pharmacologic thromboprophylaxis are included before 14weeks of gestation. The primary efficacy outcome is symptomatic recurrent VTE during pregnancy and 6weeks postpartum. The primary safety outcomes are clinically relevant bleeding, blood transfusions before 6weeks postpartum and mortality. Patients are closely monitored to detect cutaneous reactions to LMWH and are followed for 3months after delivery. A central independent adjudication committee adjudicates all suspected outcome events. CONCLUSION: The Highlow study is the first large randomised controlled trial in pregnancy that will provide high-quality evidence on the optimal dose of LWMH thromboprophylaxis for the prevention of recurrent VTE in pregnant women with a history of VTE.

[New oral anticoagulants in the treatment of venous thromboembolism]. / Nouveaux anticoagulants oraux dans le traitement curatif de la maladie thromboembolique veineuse.

Rivaroxaban (with initial increased dosage) may be used as a stand-alone therapy in patients with venous thrombo-embolism. The development of new anticoagulant drugs opened several options in the management of venous thrombo-embolism. The efficacy and safety of these new oral anticoagulants in specific population as elderly and those with renal impairment deserve future research. At that time, only rivaroxaban is licensed in France, in the treatment of deep venous thrombosis.

Epidemiology, diagnosis, treatment and management of superficial-vein thrombosis of the legs.

Recent data on lower-limb superficial-vein thrombosis (SVT) may substantially impact its clinical management. Particularly, the clear confirmation that SVT is closely linked to deep-vein thrombosis (DVT) or pulmonary embolism (PE) highlights the potential severity of the disease. DVT or PE is diagnosed in 20-30% of SVT patients. Moreover, clinically relevant symptomatic thromboembolic events complicate isolated SVT (without concomitant DVT or PE at diagnosis) in 4-8% of patients. For the first time, an anticoagulant treatment, once-daily 2.5 mg fondaparinux for 45 days, was demonstrated to be effective and safe for preventing these symptomatic thromboembolic events in patients with lower-limb isolated SVT in the randomized, placebo-controlled CALISTO study. More recent data from another randomized trial support these findings. New recommendations on the management of SVT patients, including complete ultrasonography examination of the legs and, in patients with isolated SVT, prescription of once-daily 2.5 mg fondaparinux subcutaneously for 45 days on top of symptomatic treatments, may be proposed, wherever the cost of fondaparinux is acceptable. Superficial-vein thrombosis (SVT) of the lower limbs has long been regarded as a benign, self-limiting disease, expected to resolve spontaneously and rapidly, and requiring only symptomatic treatments [1,2]. However, the perception of this disease is now changing with the recent publication of data indicating its potential severity [3] and showing for the first time the benefit of a therapeutic strategy based on the administration of an anticoagulant treatment [4]. The overall management of this frequent disease therefore needs to be reconsidered.