OBJECTIVE

A patient with ulcerative colitis refractory to standard therapy was treated with heparin for a deep vein thrombosis. Paradoxically, rectal bleeding did not increase; instead, his colitis rapidly went into remission. The same effect occurred when this patient was later treated for a pulmonary embolism. On the basis of these observations and reports of a hypercoagulable state in ulcerative colitis, heparin was tested as a therapeutic agent in nine additional patients.

METHODS

Nine of the 10 patients had ulcerative colitis poorly controlled on sulfasalazine and prednisolone. Two had associated thromboembolic disease, and one was on no medication. Patients were started on heparin in hospital, taught to self-inject subcutaneously, and discharged to continue on 10,000 U of unfractionated heparin twice daily. Current doses of sulfasalazine were maintained; prednisolone was tapered and stopped. Patients were carefully monitored for adverse side-effects. Sections of colonic mucosa from nine patients were examined for intravascular thrombosis of the mucosal blood vessels.

RESULTS

Nine patients became asymptomatic (normal stool frequency, no rectal bleeding) on combined heparin and sulfasalazine therapy; one patient had a partial improvement in symptoms. Highly significant statistical differences between pre- and posttreatment mean scores were found for all disease parameters. Intravascular fibrin thrombi were identified in sections from six of nine patients. No serious complications were associated with this use of heparin.

CONCLUSIONS

The heparin-linked remission of ulcerative colitis, observed by chance in our first patient, was followed by similar responses in eight of nine further patients. This suggests that, used as described, heparin may have a role in treating refractory ulcerative colitis.

Heparin-induced thrombocytopenia (HIT) is usually caused by platelet-activating antibodies of immunoglobulin G class that recognize platelet factor-4 (PF4) bound to heparin or certain other polyanions. Commercial enzyme immunoassays (EIAs) for PF4/polyanion-reactive antibodies detect two immunoglobulin classes (IgA and IgM) besides IgG. To investigate whether the additional detection of these antibody classes improves or worsens assay operating characteristics, we compared the sensitivity and specificity of EIAs that detect these 3 immunoglobulin classes individually with that of a commercial EIA (Genetic Testing Institute, GTI), as well as a platelet-activation assay, the serotonin-release assay (SRA). We compared the operating characteristics of these 5 assays by evaluating 448 patients, in 14 of whom clinical HIT developed, who received either unfractionated or low molecular weight heparin in prospective studies that included systematic platelet-count monitoring and serologic evaluation for anti-PF4/polyanion antibodies. We found that the SRA and IgG and commercial EIAs had similar high sensitivity for HIT; however, diagnostic specificity (for unfractionated and low molecular weight heparin, respectively) varied considerably, as follows: SRA (95.1%, 97.2%)>> IgG EIA (89.0%, 93.7%)>> GTI EIA (74.2%, 87.6%). Additional detection of IgA and IgM antibodies by the GTI EIA worsened test specificity by detecting numerous nonpathogenic antibodies. Moreover, the frequency and magnitude of IgA and IgM antibody formation in non-HIT immune responses did not differ from that exhibited by patients in whom clinical HIT developed. We conclude that an EIA that detects anti-PF4/polyanion antibodies of only the IgG class has greater diagnostic usefulness in revealing clinical HIT than does an assay that also detects IgA and IgM class antibodies.

OBJECTIVE

Low molecular weight heparins (LMWHs) offer several advantages over standard anticoagulant therapy (unfractionated heparin/warfarin) including predictable pharmacokinetics, minimal monitoring, and subcutaneous administration. Our objective was to determine the safety and efficacy of LMWHs in children.

METHODS

A prospective cohort of children treated with the LMWH enoxaparin (Rhone Poulenc Rorer) was monitored at the Hospital for Sick Children, Toronto, Canada, from March 1994 until July 1997.

RESULTS

There were 146 courses of LMWH administered for treatment and 31 courses for prophylaxis of thromboembolic events (TEs). Clinical resolution of TEs occurred in 94% of children receiving therapeutic doses of LMWH, and 96% of children receiving prophylactic doses of LMWH had no symptoms of recurrent or new TEs. Major bleeding occurred in 5% of children receiving therapeutic doses. Recurrent or new TEs occurred in 1% and 3% of children receiving therapeutic and prophylactic doses of LMWH, respectively.

CONCLUSIONS

LMWH appears to be efficacious and safe for both management and prophylaxis of TEs. The results of this cohort study justify a randomized controlled trial comparing LMWH with standard therapy for the management of TEs in children.

OBJECTIVE

There is no consensus whether to use unfractionated heparin or low-molecular weight heparin for the treatment of cerebral venous thrombosis. We examined the effect on clinical outcome of each type of heparin.

METHODS

A nonrandomized comparison of a prospective cohort study (the International Study on Cerebral Vein and Dural Sinus Thrombosis) of 624 patients with cerebral venous thrombosis. Patients not treated with heparin (n = 107) and those who sequentially received both types of heparin (n = 99) were excluded from the primary analysis. The latter were included in a secondary analysis, allocated according to the type of heparin given first. The primary end point was functional independency at 6 months (modified Rankin scale score ≤ 2). Secondary end points were complete recovery (modified Rankin scale score 0 to 1), mortality, and new intracranial hemorrhages.

RESULTS

A total of 119 patients received low-molecular weight heparin (28%) and 302 received unfractionated heparin (72%). Significantly more patients treated with low-molecular weight heparin were functionally independent after 6 months, both in univariate analysis (odds ratio, 2.1; CI, 1.0 to 4.2) and after adjustment for prognostic factors and imbalances (odds ratio, 2.4; CI, 1.0 to 5.7). In the secondary analysis, there was a similar, nonsignificant trend (odds ratio, 1.7; CI, 0.80 to 3.6). Low-molecular weight heparin was associated with less new intracerebral hemorrhages (adjusted odds ratio, 0.29; CI, 0.07 to 1.3), especially in patients with intracerebral lesions at baseline (adjusted odds ratio, 0.19; CI, 0.04 to 0.99). There was no difference in complete recovery and mortality.

CONCLUSIONS

This nonrandomized study in patients with cerebral venous thrombosis suggests a better efficacy and safety of low-molecular weight heparin over unfractionated heparin. Low-molecular weight heparin seems preferable above unfractionated heparin for the initial treatment of cerebral venous thrombosis.

BACKGROUND

The relative importance of previous diagnosis and hereditary prothrombotic risk factors for cerebral venous thrombosis (CVT) in children in determining risk of a second cerebral or systemic venous thrombosis (VT), compared with other clinical, neuroimaging, and treatment variables, is unknown.

METHODS

We followed up the survivors of 396 consecutively enrolled patients with CVT, aged newborn to 18 years (median 5.2 years) for a median of 36 months (maximum 85 months). In accordance with international treatment guidelines, 250 children (65%) received acute anticoagulation with unfractionated heparin or low-molecular weight heparin, followed by secondary anticoagulation prophylaxis with low-molecular weight heparin or warfarin in 165 (43%).

RESULTS

Of 396 children enrolled, 12 died immediately and 22 (6%) had recurrent VT (13 cerebral; 3%) at a median of 6 months (range 0.1-85). Repeat venous imaging was available in 266 children. Recurrent VT only occurred in children whose first CVT was diagnosed after age 2 years; the underlying medical condition had no effect. In Cox regression analyses, non-administration of anticoagulant before relapse (hazard ratio [HR] 11.2 95% CI 3.4-37.0; p<0.0001), persistent occlusion on repeat venous imaging (4.1, 1.1-14.8; p=0.032), and heterozygosity for the G20210A mutation in factor II (4.3, 1.1-16.2; p=0.034) were independently associated with recurrent VT. Among patients who had recurrent VT, 70% (15) occurred within the 6 months after onset.

CONCLUSIONS

Age at CVT onset, non-administration of anticoagulation, persistent venous occlusion, and presence of G20210A mutation in factor II predict recurrent VT in children. Secondary prophylactic anticoagulation should be given on a patient-to-patient basis in children with newly identified CVT and at high risk of recurrent VT. Factors that affect recanalisation need further research.

Microvascular occlusion in sickle cell disease can be initiated by adhesion of sickle red blood cells (RBCs) to the endothelium. Our objective in this study was to verify the relevance in vivo of our discovery that sickle RBCs adhere abnormally to endothelial P-selectin in vitro. We used computer-assisted intravital microscopy to characterize RBC flow velocity (V(RBC)) in mice. We found faster V(RBC) of sickle RBCs in P-selectin knock-out and control mice than in sickle cell mice, which have increased endothelial cell P-selectin expression. Agonist peptide for murine protease-activated receptor-1 (PAR-1), which selectively activates mouse endothelial cells but not platelets, was used to assess the effects of endothelial cell P-selectin on microvascular flow. Suffusion of venules with this agonist stopped flow promptly in normal and sickle mice but not in P-selectin knock-out mice or in control mice pretreated with anti-P-selectin monoclonal antibody or unfractionated heparin (UFH). Agonist-induced slowing of flow was reversed rapidly by suffusion with UFH, provided flow had not already stopped. We conclude that endothelial cell P-selectin contributes to the microcirculatory abnormalities in sickle cell disease and that blocking P-selectin may be useful for preventing painful vasoocclusion in sickle cell disease.

BACKGROUND

Antithrombotic therapy is efficacious for the prevention of thromboembolic disease, but it necessitates careful risk-benefit assessment.

METHODS

Antithrombotic therapy data were retrospectively collected from inpatient medical records at 38 US hospitals. Patients treated for atrial fibrillation, acute myocardial infarction, deep vein thrombosis, or pulmonary embolism and patients given prophylaxis for total knee replacement, total hip replacement, or hip fracture surgery between July 1, 2000, and June 30, 2003, were randomly selected.

RESULTS

The medical records of 3778 patients (53.3% men) were included. The mean patient age was 66.1 years. Of patients with atrial fibrillation at high risk for stroke, only 54.7% received warfarin sodium, and 20.6% received neither aspirin nor warfarin. Of patients with acute myocardial infarction, only 75.5% received aspirin on hospital arrival. After orthopedic surgery procedures, only 85.6% of patients received prophylaxis with a parenteral anticoagulant agent or warfarin. In 49.4% of patients with deep vein thrombosis, pulmonary embolism, or both, unfractionated or low-molecular-weight heparin use was discontinued before an international normalized ratio of 2.0 or greater was achieved for 2 consecutive days. Patients with deep vein thrombosis or pulmonary embolism were rarely discharged from the hospital with bridge therapy (an injectable anticoagulant agent plus warfarin), although the length of hospitalization was significantly shorter than if discharged taking warfarin alone (4.0 vs 8.1 days; P < .001).

CONCLUSIONS

A significant percentage of hospitalized patients do not receive adequate antithrombotic therapy for the primary and secondary prevention of thromboembolic disease.

BACKGROUND

Primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction has traditionally been supported by unfractionated heparin, which has never been directly compared with a new anticoagulant using consistent anticoagulation and similar antiplatelet strategies in both groups. We compared traditional heparin treatment with intravenous enoxaparin in primary PCI.

METHODS

In a randomised open-label trial, patients presenting with ST-elevation myocardial infarction were randomly assigned (1:1) to receive an intravenous bolus of 0·5 mg/kg of enoxaparin or unfractionated heparin before primary PCI. Wherever possible, medical teams travelling in mobile intensive care units (ambulances) selected, randomly assigned (using an interactive voice response system at the central randomisation centre), and treated patients. Patients who had received any anticoagulant before randomisation were excluded. Patients and caregivers were not masked to treatment allocation. The primary endpoint was 30-day incidence of death, complication of myocardial infarction, procedure failure, or major bleeding. The main secondary endpoint was the composite of death, recurrent acute coronary syndrome, or urgent revascularisation. Analysis was by intention to treat. This trial is registered at ClinicalTrials.gov, number NCT00718471.

RESULTS

910 patients were assigned to treatment with enoxaparin (n=450) or unfractionated heparin (n=460). The primary endpoint occurred in 126 (28%) patients after anticoagulation with enoxaparin versus 155 (34%) patients on unfractionated heparin (relative risk [RR] 0·83, 95% CI 0·68-1·01, p=0·06). The incidence of death (enoxaparin, 17 [4%] vs heparin, 29 [6%] patients; p=0·08), complication of myocardial infarction (20 [4%] vs 29 [6%]; p=0·21), procedure failure (100 [26%] vs 109 [28%]; p=0·61), and major bleeding (20 [5%] vs 22 [5%]; p=0·79) did not differ between groups. Enoxaparin resulted in a significantly reduced rate of the main secondary endpoint (30 [7%] vs 52 [11%] patients; RR 0·59, 95% CI 0·38-0·91, p=0·015). Death, complication of myocardial infarction, or major bleeding (46 [10%] vs 69 [15%] patients; p=0·03), death or complication of myocardial infarction (35 [8%] vs 57 [12%]; p=0·02), and death, recurrent myocardial infarction, or urgent revascularisation (23 [5%] vs 39 [8%]; p=0·04) were all reduced with enoxaparin.

CONCLUSIONS

Intravenous enoxaparin compared with unfractionated heparin significantly reduced clinical ischaemic outcomes without differences in bleeding and procedural success. Therefore, enoxaparin provided an improvement in net clinical benefit in patients undergoing primary PCI.

BACKGROUND

Direction de la Recherche Clinique, Assistance Publique-Hôpitaux de Paris; Sanofi-Aventis.

BACKGROUND

No published data have systematically documented pulmonary artery pressure over an intermediate time period after submassive pulmonary embolism (PE). The aim of this work was to document the rate of pulmonary hypertension, as assessed noninvasively by estimated right ventricular systolic pressure (RVSP) of>>or= 40 mm Hg 6 months after the diagnosis of submassive PE.

METHODS

We enrolled 200 normotensive patients with CT angiography-proven PE and a baseline echocardiogram to estimate RVSP. All patients received therapy with unfractionated heparin initially, but 21 patients later received alteplase in response to circulatory shock or respiratory failure. Patients returned at 6 months for repeat RVSP measurement, and assessments of the New York Heart Association (NYHA) score and 6-min walk distance (6MWD).

RESULTS

Six months after receiving a diagnosis, 162 of 180 survivors (90%) returned for follow-up, including 144 patients who had been treated with heparin (heparin-only group) and 18 patients who had been treated with heparin plus alteplase (heparin-plus-alteplase group). Among the heparin-only patients, the RVSP at diagnosis was>>or= 40 mm Hg in 50 of 144 patients (35%; 95% CI, 27% to 43%), compared with 10 of 144 patients at follow-up (7%; 95% CI, 3% to 12%). However, the RVSP at follow-up was higher than the baseline RVSP in 39 of 144 patients (27%; 95% CI, 9% to 35%), and 18 of these 39 patients had a NYHA score of>>or= 3 or exercise intolerance (6MWD, < 330 m). Among heparin-plus-alteplase patients, the RVSP was>>or= 40 mm Hg in 11 of 18 patients at diagnosis (61%; 95% CI, 36% to 83%), compared with 2 of 18 patients at follow-up (11%; 95% CI, 1% to 35%). The RVSP at follow-up was not higher than at the time of diagnosis in any of the heparin-plus-alteplase patients (95% CI, 0% to 18%).

CONCLUSIONS

Six months after experiencing submassive PE, a significant proportion of patients had echocardiographic and functional evidence of pulmonary hypertension.

OBJECTIVE

To assess the benefits in terms of reductions in the risks of deep vein thrombosis (DVT) and of pulmonary embolism (PE), and hazards in terms of major bleeding, of: (i) mechanical compression; (ii) oral anticoagulants; (iii) dextran; and (iv) regional anaesthesia (as an alternative to general anaesthesia) in surgical and medical patients.

METHODS

Electronic databases, search of Antithrombotic Trialists' Collaboration database, contact with trialists and manufacturers.

METHODS

All trials identified as fitting the selection criteria were independently assessed. The primary outcomes were DVT, PE and major bleeding events, and proximal venous thrombosis (PVT) and fatal PE were secondary outcomes. Trials were subdivided into those that had assessed a method as the only means of thromboprophylaxis ('monotherapy') and those that had assessed the effects of adding a method to another form of thromboprophylaxis ('adjunctive therapy').

RESULTS

Mechanical compression methods reduced the risk of DVT by about two-thirds when used as monotherapy and by about half when added to a pharmacological method. These benefits were similar irrespective of the particular method used (graduated compression stockings, intermittent pneumatic compression or footpumps) and were similar in each of the surgical groups studied. Mechanical methods reduced the risk of PVT by about half and the risk of PE by two-fifths. Oral anticoagulants, when used as monotherapy, reduced the risk of DVT and of PVT by about half, and this protective effect appeared similar in each of the surgical groups studied. There was an apparently large four-fifths reduction in the role of PE, but not only was the magnitude of this reduction statistically uncertain, but also pulmonary embolism was reported by a minority of trials, so it may be subject to selection bias. Oral anticoagulant regimens approximately doubled the risk of major bleeding and appeared less effective at preventing DVT than heparin regimens, although were associated with less major bleeding. Dextran reduced the risk of DVT and of PVT by about half, again irrespective of the type of surgery, but too few studies had reported PE to provide reliable estimates of effect on this outcome. Dextran appeared to be less effective at preventing DVT than the heparin regimens studied. Dextran was associated with an increased risk of bleeding, but too few bleeds had occurred for the size of this excess risk to be estimated reliably. Compared with general anaesthesia, regional anaesthesia reduced the risk of DVT by about half, and this benefit appeared similar in each of the surgical settings studied. Regional anaesthesia was associated with less major bleeding than general anaesthesia.

CONCLUSIONS

In the absence of a clear contraindication (such as severe peripheral arterial disease), patients undergoing a surgical procedure would be expected to derive net benefit from a mechanical compression method of thromboprophylaxis (such as graduated compression stockings), irrespective of their absolute risk of venous thromboembolism. Patients who are considered to be at particularly high risk of venous thromboembolism may also benefit from a pharmacological thromboprophylactic agent, but since oral anticoagulant and dextran regimens appear less effective at preventing DVT than standard low-dose unfractionated heparin or low molecular weight heparin regimens, they may be less suitable for patients at high risk of venous thromboembolism, even though they are associated with less bleeding. Whenever feasible, the use of regional anaesthesia as an alternative to general anaesthesia may also provide additional protection against venous thromboembolism. There is little information on the prevention of venous thromboembolism among high-risk medical patients (such as those with stroke), so further randomised trials in this area would be helpful.

OBJECTIVE

To evaluate the efficacy and safety of two subcutaneous prophylactic regimens for postoperative deep vein thrombosis after total hip replacement.

METHODS

Prospective open randomised multicentre trial.

METHODS

28 European departments of orthopaedic surgery.

METHODS

All patients had bilateral phlebography 10 days after surgery. 31 patients receiving low molecular weight heparin and 29 receiving unfractionated heparin were excluded from the efficacy analysis for various reasons.

METHODS

349 patients undergoing total hip replacement between September 1988 and May 1989. 174 patients received subcutaneously a low molecular weight heparin (Fraxiparine) with anti-factor Xa activity of 41 IU/kg/day for three days, then 62 IU/kg/day from day 4 to day 10. 175 patients received subcutaneous unfractionated heparin at intervals of eight hours; doses were adjusted to maintain the activated thromboplastin time at two to five seconds above control values.

METHODS

Total incidence of deep vein thrombosis and incidence of proximal deep vein thrombosis on bilateral phlebography.

RESULTS

The total incidence of deep vein thrombosis was 16% in patients receiving unfractionated heparin and 12.6% in patients receiving low molecular weight heparin (p = 0.45), and the incidence of thrombosis of the proximal veins was 13.1% and 2.9% respectively (p less than 0.001). Four patients receiving unfractionated heparin and one receiving low molecular weight heparin developed pulmonary embolism. The incidence of bleeding complications was low and comparable in the two groups.

CONCLUSIONS

Low molecular weight heparin is at least as effective as unfractionated heparin in preventing deep vein thrombosis and is more effective at preventing thrombosis of the proximal veins in patients undergoing hip replacement. Low molecular weight heparin is not more likely to cause bleeding complications and is simpler to give than unfractionated heparin.

Cancer patients treated for venous thromboembolism with low molecular weight heparin (LMWH) have a better survival rate than patients treated with unfractionated heparin (UFH). Because fibrin-associated angiogenesis is an important determinant in the progression and metastasis of many solid tumors, the effects of heparins on in vitro angiogenesis were investigated. Both UFH and LMWH inhibited bFGF-induced proliferation of human microvascular endothelial cells (hMVECs) to the same the extent (36-60%). VEGF165-induced proliferation was inhibited to a to a lesser extent (19-33%). Turbidity measurements and electron microscopy showed that the presence of LMWH during polymerization of the fibrin matrix led to a more transparent rigid network with thin fibrin bundles, whereas the presence of UFH resulted in a more opaque more porous network with thick fibrin fibers. We used a human in vitro angiogenesis model, which consisted of hMVECs seeded on top of a fibrin matrix, and stimulated the cells with basic fibroblast growth factor plus tumor necrosis factor a to induce capillary-like tubular structures. The formation of capillary-like tubular structures was retarded with matrices polymerized in the presence of LMWH (46% inhibition compared with a control matrix for both 1.5 and 10 units/ml LMWH), whereas matrices polymerized in the presence of UFH facilitated tubular structure formation (72 and 36% stimulation compared with a control matrix for 1.5 and 10 units/ml UFH, respectively). Similar results were obtained for cells stimulated with vascular endothelial growth factor plus tumor necrosis factor alpha. These data demonstrate the inhibitory effect of heparins on proliferation of hMVECs and provide a novel mechanism by which LMWH may affect tumor progression, namely reduced ingrowth of microvascular structures in a fibrinous stroma matrix by rendering it less permissive for invasion.

BACKGROUND

A low-molecular-weight heparin, enoxaparin sodium, has been shown to be effective and safe in preventing deep vein thrombosis both in general surgery and in high-risk orthopedic surgery. We conducted a controlled, randomized trial with enoxaparin in the treatment of established deep vein thrombosis.

METHODS

In a multicenter trial, we compared fixed-dose subcutaneous enoxaparin, given twice daily, with adjusted-dose intravenous unfractionated heparin (UFH) given by continuous intravenous infusion for the initial 10 days of treatment of patients with proximal vein thrombosis. The primary efficacy outcome was the change of the size of the thrombus assessed by repeated venograms between day 0 and day 10. The primary analysis of safety was based on the incidence of major bleeding during 10 days of treatment.

RESULTS

There were 67 patients in each group. Venographic assessment of clot size evolution between day 0 and day 10 showed a statistically significant superiority (P < .002) of enoxaparin over the reference treatment with UFH. Moreover, the incidence of overall recurrent thromboembolic events during 10 days of treatment was significantly higher (P < .002) in the UFH group (seven of 67) than in the enoxaparin group (one of 67). There were no serious bleeding complications in either group.

CONCLUSIONS

Enoxaparin is at least as effective and safe as UFH under the conditions of this study. Moreover, it is more comfortable for patients and less time-consuming for nurses and laboratories. Thus, our study confirmed, with the use of enoxaparin, other observations that low-molecular-weight heparin provides a real therapeutic advance in the treatment of deep vein thrombosis.

Low-molecular-weight heparins (LMWHs) comprise a group in the class of antithrombotic medications, a class headed by unfractionated heparin (UFH). The LMWHs, with mean molecular weights of 4.0-6.0 kD, differ in their individual manufacturing processes, the distribution of their fragment molecular weights, their in vitro potency (anti-Xa, antithrombin and anticoagulant activities) and, consequently, in their biodynamic patterns, recommended dose regimen, and efficacy/safety ratio. Their drug disposition profiles have been evaluated using two significant markers of their pharmacodynamic activity, namely anti-Xa and anti-IIa activities. Since they are mainly administered subcutaneously, then compared to UFH, they are almost completely absorbed (F>> or = 90%) and, in contrast to UFH, those for which data are available in the literature exhibit linear pharmacokinetics with proportionality between anti-Xa (and anti-IIa in some cases) plasma concentration and dose, and stationary distribution volume and clearance processes when the dosage is increased. Their distribution volume is close to the blood volume, they are partially metabolized by desulphatation and depolymerization, but urinary excretion of anti-Xa activity for enoxaparin, dalteparin and nadroparin, all given at doses for prevention of venous thrombosis, is between 5 and 10% of the injected dose. However, these LMWHs differ in the extent of their non-renal clearance, resulting in different apparent elimination half-life values and relative apparent bioavailability. When considering certain at-risk situations, using doses for preventing thromboembolism, the LMWHs do not significantly cross the placenta of pregnant women and their excretion profiles are only slightly altered in severe (endogenous creatinine clearance less than 15 ml/min) renal disease patients when given at doses recommended for prevention of venous thromboembolism. Because of the differences among LMWHs, the clinical profile of a given LMWH cannot be extrapolated to another one or generalized to the whole LMWH family.

BACKGROUND

Venous thromboembolism is a common, life-threatening complication in neurosurgery, but prophylaxis with anticoagulant agents has not gained wide acceptance because of concern about intracranial bleeding. We performed a meta-analysis of controlled randomized trials on the efficacy and safety of heparin in the prophylaxis of venous thromboembolism in neurosurgery.

OBJECTIVE

To review the clinical benefit of prophylaxis of venous thromboembolism with heparin in the controversial setting of neurosurgery.

METHODS

Relevant trials evaluating heparin for prophylaxis of venous thromboembolism in neurosurgery were identified by a MEDLINE search, scan of meeting abstracts, and scrutiny of the references of original articles and reviews. Four controlled randomized studies, 3 of which involved low-molecular-weight heparin, were included in the analysis, and 4 uncontrolled studies are commented on in the article. The outcome measure (observed minus expected number of events) and its variance were calculated for each single trial and then summed. Two-tailed P values and 95% confidence intervals (CIs) were calculated. Efficacy was assessed per protocol and safety by intention-to-treat analysis. The homogeneity of the studies was tested with the chi(2) statistic. The results were also expressed as number needed for 1 extra event.

RESULTS

A total of 187 thromboembolic events were recorded in 827 patients (22.6%). Heparin prophylaxis resulted in a 45% relative risk reduction of venous thromboembolic events (odds ratio [OR], 0.48; 95% CI, 0.35-0.66; P<. 001). Nineteen major bleedings were recorded in 1022 patients. None were fatal. Heparin treatment resulted in a 71% relative risk increase of major bleeding (OR, 1.72; 95% CI, 0.69-4.27; P =.24). The number needed to treat was 7.7 for venous thromboembolism and 16 for proximal deep vein thrombosis. The number needed to harm was 102 (115 for low-molecular-weight heparin).

CONCLUSIONS

Low-molecular-weight and unfractionated heparin have been shown to be effective for prophylaxis of venous thromboembolism in elective neurosurgery without excessive bleeding risk.

Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) has caused a pandemic of historic proportions and continues to spread globally, with enormous consequences to human health. Currently there is no vaccine, effective therapeutic or prophylactic. Like other betacoronaviruses, attachment and entry of SARS-CoV-2 is mediated by the spike glycoprotein (SGP). In addition to its well-documented interaction with its receptor, human angiotensin converting enzyme 2 (hACE2), SGP has been found to bind to glycosaminoglycans like heparan sulfate, which is found on the surface of virtually all mammalian cells. Here, we pseudotyped SARS-CoV-2 SGP on a third generation lentiviral (pLV) vector and tested the impact of various sulfated polysaccharides on transduction efficiency in mammalian cells. The pLV vector pseudotyped SGP efficiently and produced high titers on HEK293T cells. Various sulfated polysaccharides potently neutralized pLV-S pseudotyped virus with clear structure-based differences in anti-viral activity and affinity to SGP. Concentration-response curves showed that pLV-S particles were efficiently neutralized by a range of concentrations of unfractionated heparin (UFH), enoxaparin, 6-O-desulfated UFH and 6-O-desulfated enoxaparin with an IC₅₀ of 5.99 μg/L, 1.08 mg/L, 1.77 μg/L, and 5.86 mg/L respectively. In summary, several sulfated polysaccharides show potent anti-SARS-CoV-2 activity and can be developed for prophylactic as well as therapeutic purposes.Importance The recent emergence of Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) in Wuhan, China in late 2019 and its subsequent spread to the rest of the world has created a pandemic situation unprecedented in modern history. While ACE2 has been identified as the viral receptor, cellular polysaccharides have also been implicated in virus entry. The SARS-CoV-2 spike glycoprotein (SGP) binds to glycosaminoglycans like heparan sulfate, which is found on the surface of virtually all mammalian cells. Here, we report structure-based differences in anti-viral activity and affinity to SGP for several sulfated polysaccharides, including both well-characterized FDA-approved drugs and novel marine sulfated polysaccharides, which can be developed for prophylactic as well as therapeutic purposes.

In contrast with extensive documentation in patients treated with unfractionated heparin (UFH), the incidence of heparin-induced thrombocytopenia (HIT) in medical patients receiving low-molecular-weight heparin (LMWH) is less well defined. In a prospective cohort study, the platelet count was monitored in 1754 consecutive patients referred to 17 medical centers and treated with LMWH for prophylaxis or treatment of thromboembolic disorders. The diagnosis of HIT was accepted in case of a platelet drop of at least 50%, the absence of obvious explanations for thrombocytopenia, and the demonstration of heparin-dependent IgG antibodies. HIT developed in 14 patients (0.80%; 95% CI, 0.43%-1.34%), in all of them within the first 2 weeks, and was more frequent in patients who had (1.7%) than in those who had not (0.3%) been exposed to UFH or LMWH (OR = 4.9; 95% CI, 1.5-15.7). The prevalence of thromboembolic complications in HIT patients (4 of 14; 28.6%) was remarkably higher than that (41 of 1740; 2.4%) observed in the remaining patients (OR = 16.6; 95% CI, 5.0-55.0). Immune thrombocytopenia and related thromboembolism may complicate the clinical course of medical patients treated with LMWH with a frequency that is not different from that observed with the use of UFH. The previous administration of heparin increases the rate of HIT.

A double blind randomized trial comparing subcutaneous enoxaparin (40 mg once daily) with standard unfractionated calcium heparin administered at a dose of 5,000 units every 8 hours in patients undergoing elective hip replacement has been performed. Treatment regimens began 12 hours preoperatively with enoxaparin, 2 hours preoperatively with standard unfractionated calcium heparin, and were continued for 15 days or until discharge. Venography was performed in all patients. Two hundred thirty-seven patients were included in the study: 113 received unfractionated heparin and 124 received enoxaparin. The incidence of proximal deep vein thrombosis was reduced from 18.5% in the unfractionated heparin group to 7.5% in the enoxaparin group (p = 0.014), and the incidence of total deep vein thrombosis was similarly reduced from 25% to 12.5% (p = 0.03). There were two major bleeding episodes and one minor bleed in the enoxaparin group compared to two minor bleeds in the unfractionated heparin group. Patients who received enoxaparin required fewer red blood cell transfusions and had a significantly higher hemoglobin on postoperative days 3 and 4. Thus prophylaxis with enoxaparin, 40 mg once daily, is simple, safe and more effective than standard low dose unfractionated heparin in preventing deep vein thrombosis in patients undergoing elective hip replacement.

BACKGROUND

Anticoagulation in cardioversion of atrial fibrillation is currently performed with unfractionated heparin (UFH) and oral anticoagulants, with or without guidance by transesophageal echocardiography (TEE). Low-molecular-weight heparins may reduce the risk of bleeding, may obviate the need for intravenous access, and do not require frequent anticoagulation monitoring.

RESULTS

In a randomized, prospective multicenter trial, we compared the safety and efficacy of enoxaparin administered subcutaneously with intravenous UFH followed by the oral anticoagulant phenprocoumon in 496 patients scheduled for cardioversion of atrial fibrillation of >48 hours' and < or =1 year's duration. Patients were stratified to cardioversion with (n=431) and without (n=65) guidance by TEE. The study aimed to demonstrate noninferiority of enoxaparin compared with UFH+phenprocoumon with regard to the incidence of embolic events, all-cause death, and major bleeding complications. Secondary end points included successful cardioversion, maintenance of sinus rhythm until study end, and minor bleeding complications. Of 496 randomized patients, 428 were analyzed per protocol. Enoxaparin was noninferior to UFH+phenprocoumon with regard to the incidence of the composite primary end point in a per-protocol analysis (7 of 216 patients versus 12 of 212 patients, respectively; P=0.016) and in an intention-to-treat analysis (7 of 248 patients versus 12 of 248 patients, respectively; P=0.013). There was no significant difference between the 2 groups in the number of patients reverted to sinus rhythm.

CONCLUSIONS

Enoxaparin is noninferior to UFH+phenprocoumon for prevention of ischemic and embolic events, bleeding complications, and death in TEE-guided cardioversion of atrial fibrillation. Its easier application and more stable anticoagulation may make it the preferred drug for initiation of anticoagulation in this setting.

The Haemostasis and Thrombosis Task Force of the British Committee for Standards in Haematology has produced a concise practical guideline to highlight the key issues in the management of heparin-induced thrombocytopenia (HIT) for the practicing physician in the UK. The guideline is evidence-based and levels of evidence are included in the body of the article. All patients who are to receive heparin of any sort should have a platelet count on the day of starting treatment. For patients who have been exposed to heparin in the last 100 d, a baseline platelet count and a platelet count 24 h after starting heparin should be obtained. For all patients receiving unfractionated heparin (UFH), alternate day platelet counts should be performed from days 4 to 14. For surgical and medical patients receiving low-molecular-weight heparin (LMWH) platelet counts should be performed every 2-4 d from days 4 to 14. Obstetric patients receiving treatment doses of LMWH should have platelet counts performed every 2-4 d from days 4 to 14. Obstetric patients receiving prophylactic LMWH are at low risk and do not need routine platelet monitoring. If the platelet count falls by 50% or more, or falls below the laboratory normal range and/or the patient develops new thrombosis or skin allergy between days 4 and 14 of heparin administration HIT should be considered and a clinical assessment made. If the pretest probability of HIT is high, heparin should be stopped and an alternative anticoagulant started at full dosage unless there are significant contraindications while laboratory tests are performed. Platelet activation assays using washed platelets have a higher sensitivity than platelet aggregation assays but are technically demanding and their use should be restricted to laboratories experienced in the technique. Non-expert laboratories should use an antigen-based assay of high sensitivity. Only IgG class antibodies need to be measured. Useful information is gained by reporting the actual optical density, inhibition by high concentrations of heparin, and the cut-off value for a positive test rather than simply reporting the test as positive or negative. In making a diagnosis of HIT the clinician's estimate of the pretest probability of HIT together with the type of assay used and its quantitative result (enzyme-linked immunosorbent assay, ELISA, only) should be used to determine the overall probability of HIT. Clinical decisions should be made following consideration of the risks and benefits of treatment with an alternative anticoagulant. For patients with strongly suspected or confirmed HIT, heparin should be stopped and full-dose anticoagulation with an alternative, such as lepirudin or danaparoid, commenced (in the absence of a significant contraindication). Warfarin should not be used until the platelet count has recovered. When introduced in combination with warfarin, an alternative anticoagulant must be continued until the International Normalised Ratio (INR) is therapeutic for two consecutive days. Platelets should not be given for prophylaxis. Lepirudin, at doses adjusted to achieve an activated partial thromboplastin time (APTT) ratio of 1.5-2.5, reduces the risk of reaching the composite endpoint of limb amputation, death or new thrombosis in patients with HIT and HIT with thrombosis (HITT). The risk of major haemorrhage is directly related to the APTT ratio, lepirudin levels and serum creatinine levels. The patient's renal function needs to be taken into careful consideration before treatment with lepirudin is commenced. Severe anaphylaxis occurs rarely in recipients of lepirudin and is more common in previously exposed patients. Danaparoid in a high-dose regimen is equivalent to lepirudin in the treatment of HIT and HITT. Danaparoid at prophylactic doses is not recommended for the treatment of HIT or HITT. Patients with previous HIT who are antibody negative (usually so after >100 d) who require cardiac surgery should receive intraoperative UFH in preference to other anticoagulants that are less validated for this purpose. Pre- and postoperative anticoagulation should be with an anticoagulant other than UFH or LMWH. Patients with recent or active HIT should have the need for surgery reviewed and delayed until the patient is antibody negative if possible. They should then proceed as above. If deemed appropriate early surgery should be carried out with an alternative anticoagulant. We recommend discussion of these complex cases requiring surgery with an experienced centre. The diagnosis must be clearly recorded in the patient's medical record.

Two hundred and four consecutive patients with venographically confirmed deep vein thrombosis (DVT) were randomised either to a low molecular weight heparin, Fragmin, administered subcutaneously (s.c.) once daily as a fixed dose of 200 IU anti-factor Xa/kg or to continuous intravenous infusion of unfractionated heparin (UFH). The UFH dose was adjusted to maintain the activated partial thromboplastin time between 1.5 and 3.0 times the upper limit of the reference value at each centre. Fragmin or UFH was given for a minimum of 5 days until anticoagulation with warfarin, given from day 1, was established (i.e. an Internation Normalised Ratio, of 2.0-3.0). A second venogram was obtained after Fragmin or UFH treatment. There were no significant differences in the change in mean Marder score before and after treatment between the two treatment groups, irrespective of thrombus localisation. No major bleeding events, symptomatic pulmonary embolism, symptomatic thrombosis progression or death occurred during hospitalisation. Eight documented venous thromboembolic events occurred before the follow-up visit 6 months after randomisation: 5 in patients treated with Fragmin and 3 in those treated with UFH. Six of these events occurred after cessation of warfarin treatment. In conclusion Fragmin given s.c. once daily in a fixed dose adjusted for body weight, is no less effective or safe than a continuous infusion of UFH in the initial treatment of acute DVT.

OBJECTIVE

To assess the benefit of short-term low molecular weight heparin nadroparin compared with unfractionated heparin in unstable angina or non-Q wave myocardial infarction patients and to determine whether a longer, 2-week low molecular weight heparin regimen would offer additional clinical benefit.

RESULTS

This was a multicentre, prospective, randomized, double-blind study in three parallel groups, involving 3468 patients. Patients received one of three treatment regimens: the unfractionated heparin group received an intravenous bolus of unfractionated heparin 5000 IU, followed by an activated partial thromboplastin time adjusted infusion of unfractionated heparin for 6+/-2 days; the nadroparin 6 group received an intravenous bolus of nadroparin 86 anti-Xa IU. kg(-1), followed by twice daily subcutaneous injections of nadroparin 86 anti-Xa IU. kg(-1)for 6+/-2 days, and the nadroparin 14 group received an intravenous bolus of nadroparin 86 anti-Xa IU. kg(-1), followed by twice daily subcutaneous injections of nadroparin 86 anti-Xa IU. kg(-1)for 14 days. No statistically significant differences were observed between the three treatment regimens with respect to the primary outcome (cardiac death, myocardial infarction, refractory angina, or recurrence of unstable angina at day 14). The absolute differences between the groups in the incidence of the primary outcome were: -0.3% (P=0.85) for the nadroparin 6 group vs the unfractionated heparin group and +1.9% (P=0.24) for the nadroparin 14 group vs the unfractionated heparin group. Furthermore, there were no significant intergroup differences regarding any of the secondary efficacy outcomes. However, there was an increased risk of major haemorrhages in the nadroparin 14 group compared with unfractionated heparin (3.5% vs 1.6%;P=0.0035).

CONCLUSIONS

Treatment with nadroparin for 6+/-2 days provides similar efficacy and safety to treatment with unfractionated heparin, for the same period, in the therapeutic management of acute unstable angina or non-Q wave myocardial infarction, and may be easier to administer. A prolonged regimen of nadroparin (14 days) does not provide any additional clinical benefit.