BACKGROUND

Patients with mechanical heart valves require life-long anticoagulation. We report here the first large and comparative series of consecutive patients anticoagulated with low molecular weight heparin (LMWH) after mechanical heart valve replacement.

RESULTS

In this comparative, nonrandomized study, 208 consecutive patients who underwent a single or double heart valve replacement with mechanical prostheses were anticoagulated subcutaneously with unfractionated heparin (UH) in the first period (n=106) and LMWH in the second phase (n=102) of the study. Baseline characteristics were similar in the 2 groups. The mean durations of UH and LMWH treatments were 13.6+/-0.5 and 14.1+/-0.6 days, respectively (not significant). On the second day of treatment, 87% of patients treated with LMWH had an anti-Xa activity within the range of efficacy (0.5 to 1 IU/mL), but only 9% of UH-treated patients had an activated partial-thromboplastin time value within the therapeutic range (1.5 to 2.5 times control, P<0.0001 between the 2 groups). On the last day of prescription, all LMWH-treated patients had anti-Xa activity above 0.5 IU/mL, but 19% were above 1 IU/mL. In the UH group, 27% of patients had an activated partial-thromboplastin time above 1.5 times control, but 62% were overanticoagulated. Two major bleedings occurred in each group, and one stroke occurred in the UH group.

CONCLUSIONS

In this first comparative study, anticoagulation with LMWHs after mechanical heart valve replacement appears feasible, provides adequate biological anticoagulation, and compares favorably with UH anticoagulation. Randomized studies are now needed to further evaluate this new therapeutic approach.

BACKGROUND

One-year follow-up data from the Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q-Wave Coronary Events (ESSENCE) trial show that use of low-molecular-weight heparin (enoxaparin) compared with unfractionated heparin in patients hospitalized with unstable angina or non-Q-wave myocardial infarction is associated with a 10% reduction in the cumulative 1-year risk of death, myocardial infarction, or recurrent angina. Given the higher acquisition cost of enoxaparin relative to unfractionated heparin, we assessed whether the reduced use of revascularization procedures and related care makes enoxaparin a cost-saving therapy in Canada.

RESULTS

We analyzed cumulative 1-year resource use data on the 1259 ESSENCE patients enrolled in Canadian centers (40% of the total ESSENCE sample). Patient-specific data on use of drugs, diagnostic cardiac catheterization, percutaneous transluminal coronary angioplasty, coronary artery bypass grafting, and hospital days were available from the initial hospital stay and cumulative to 1 year. Hospital resources were costed with the use of data from a teaching hospital in southern Ontario that is a participant in the Ontario Case Costing Project. During the initial hospital stay, use of enoxaparin was associated with reduced use of diagnostic catheterization and revascularization procedures, with the largest effect being reduced use of percutaneous transluminal coronary angioplasty (15.0% vs 10.6%; P =.03). At 1 year, the reduced risk and costs of revascularization more than offset increased drug costs for enoxaparin, producing a cost-saving per patient of $1485 (95% confidence interval $-93 to $3167; P =.06). Sensitivity analysis with lower hospital per diem costs from a community hospital in Ontario still predicts cost savings of $1075 per patient over a period of 1 year.

CONCLUSIONS

The acquisition and administration cost of enoxaparin is higher than for unfractionated heparin ($101 vs $39), but in patients with acute coronary syndrome, the reduced need for hospitalization and revascularization over a period of 1 year more than offsets this initial difference in cost. Evidence from this Canadian substudy of ESSENCE supports the view that enoxaparin is less costly and more effective than unfractionated heparin in this indication.

The aim of the study was to compare the efficacy and safety of once-daily subcutaneous injection of dalteparin, a low molecular weight heparin, with that of intravenous unfractionated heparin in the treatment of deep venous thrombosis (DVT). Patients were included if they had deep venous thrombosis distal to inguinal ligament and were randomised either before, if it was considered necessary, or after phlebographic verification of the diagnosis. There was no pre-inclusion treatment with unfractionated heparin. One hundred and twenty patients received dalteparin, administered subcutaneously once-daily at a fixed dose of 200 IU anti-factor Xa/kg, and 133 patients received a continuous intravenous infusion of unfractionated heparin (UFH). Oral anticoagulation was started on the first or second day, and initial treatment with dalteparin or UFH discontinued when the prothrombin time was in the therapeutic range (2 < INR < 3) on two consecutive days. Control phlebograms were taken within 4 days, thereafter. There were no significant differences between the two initial treatment groups in improvements in Marder score. Two major bleeding events occurred in the UFH group versus none in the dalteparin group. One patient in each group experienced clinically significant pulmonary embolism. During a mean follow-up period of 6.9 +/- 1.5 months, recurrent DVT occurred in four patients in the dalteparin group and in two of the UFH group. These results confirm those of a previous study on dalteparin in the initial treatment of DVT, and suggest that dalteparin administered once-daily at a fixed dose of 200 UI/kg is as effective and well-tolerated as UFH in patients with DVT below the inguinal ligament. The present study also demonstrates that dalteparin can be started as soon as the diagnosis of DVT is suspected and without pre-treatment with UFH. Given that the administration of once-daily subcutaneous injections needs not require a patient to be hospitalised, studies to investigate the possibility of using dalteparin for the initial treatment of DVT in the outpatient setting are warranted.

This pilot study was designed to determine whether the low molecular weight heparin, enoxaparin, could be used for elective percutaneous coronary intervention (PCI) to provide antithrombotic effects without the full systemic anticoagulation that occurs with the use of unfractionated heparin. Sixty patients were randomized to receive intravenous enoxaparin (1 mg/kg bolus dose) or unfractionated heparin at the time of coronary intervention. Laboratory testing was performed at baseline, 5 minutes, and 4 hours after study drug to test if a single bolus dose of intravenous enoxaparin can consistently achieve therapeutic antithrombotic effect, thus eliminating the need for multiple doses of heparin and closely monitoring levels of anticoagulation during PCI. Thirty percent of patients who received unfractionated heparin required a second bolus of intravenous heparin to achieve the target-activated clotting time of 300 seconds before PCI. Enoxaparin showed antithrombotic properties comparable to that of unfractionated heparin as measured by anti-Xa levels, with less inhibition of thrombin (factor IIa) at the time points measured (p <0.0001). Angioplasty success rates, in-hospital ischemia, bleeding, and vascular complications were similar in both groups. Thus, intravenous enoxaparin has predictable and effective antithrombotic effects during elective PCI. Although the level of anticoagulation attained with enoxaparin is significantly lower than that after unfractionated heparin, no increase in ischemic complications were noted. The use of a single bolus of intravenous enoxaparin, without the need for measuring the activated clotting time or titrating heparin anticoagulation, has the potential for simplifying the performance and perhaps enhancing the safety of PCI.

OBJECTIVE

Although a 140 U/kg dose of unfractionated heparin (UFH) was comparable with bivalirudin in terms of net clinical outcome in the Intracoronary Stenting and Antithrombotic Regimen: Rapid Early Action for Coronary Treatment (ISAR-REACT) 3 trial, it was associated with a higher risk of bleeding. We designed this study to assess whether a reduction in the UFH dose from 140 to 100 U/kg is associated with improved net clinical outcome.

RESULTS

A total of 2505 biomarker negative patients undergoing percutaneous coronary intervention (PCI) after clopidogrel pre-treatment received a single bolus of 100 U/kg UFH. The primary endpoint was net clinical outcome-a quadruple endpoint of death, myocardial infarction, urgent target-vessel revascularization within 30 days, or in-hospital REPLACE 2 defined major bleeding. The primary comparison was with the historical UFH group of ISAR-REACT 3 (2281 patients). In a second analysis, we checked for non-inferiority against the historical bivalirudin arm of ISAR-REACT 3 (2289 patients). The incidence of the primary endpoint was 7.3% in the lower UFH dose group compared with 8.7% in the higher UFH dose group [hazard ratio (HR) 0.81; 95% confidence interval (CI) 0.67-1.00; P = 0.045]. The incidence of major bleeding was 3.6% in the lower UFH dose group and 4.6% in the higher UFH dose group (HR 0.79; 95% CI 0.59-1.05; P = 0.11). The lower UFH dose met the criterion of non-inferiority compared with bivalirudin (P < 0.001).

CONCLUSIONS

In biomarker negative patients undergoing PCI after clopidogrel loading, a reduced dose of 100 U/kg UFH provided net clinical benefit compared with the historical control of 140 U/kg UFH in the ISAR-REACT 3 trial. The benefit was mostly driven by reduction in bleeding.

BACKGROUND

URL www.clinicaltrials.gov; Unique identifier NCT00735280.

Osteoporosis is a well-recognized complication of long-term heparin use. However, the mechanisms by which heparin can influence bone metabolism are unclear. We report here that unfractionated heparin stimulates the process of bone resorption and that the low molecular weight heparins (LMWHs), enoxaparin, fragmin, logiparin, and ardeparin produce significantly less calcium loss than unfractionated heparin. To assess calcium loss from bone, we quantified the release of 45Ca into the culture medium of fetal rat calvaria. 45Ca release was increased in a dose-dependent manner by the addition of either unfractionated heparin or the LMWHs; but more than 50-fold higher LMWH concentrations were required to obtain an equivalent effect to unfractionated heparin. Thus, at concentration>> or = 2 micrograms/mL (0.35 anti-Xa units/mL), unfractionated heparin stimulated 45Ca release 1.53 +/- 0.06 fold. 45Ca release was increased to a similar extent by the addition of either 10(-7) mol/L parathyroid hormone (PTH) or 10(-6) mol/L 1,25 dihydroxyvitamin D3 (1,25 Vit D3). In contrast to unfractionated heparin, LMWH concentrations>> or = 100 micrograms/mL >> or = 14.0 anti-Xa units/mL) were required before maximum isotope release was observed. At concentrations well above therapeutic levels, the LMWHs stimulated 45Ca release by only 1.25 /+- 0.01-fold. Heparins with high and low antithrombin III affinities stimulated 45Ca release equally well. Both size and sulfation were found to be major determinants of heparin's ability to promote isotope release. Thus, the ability of defined heparin fragments to stimulate 45Ca release correlated with their molecular weight, and after N-desulfation the ability of heparin to induce isotope release was greatly diminished. Dermatan sulfate had no effect on 45Ca release. We conclude that size and sulfation are major determinants of heparin's ability to promote bone resorption and that the risk of heparin-induced osteoporosis may be reduced by the use of LMWH preparations.

OBJECTIVE

To review literature evaluating the use of fondaparinux for thromboembolic treatment and prophylaxis in patients with heparin-induced thrombocytopenia (HIT).

METHODS

A MEDLINE search (1966-February 2006) was conducted using the search terms fondaparinux, heparin, low-molecular-weight heparin, and thrombocytopenia to identify English-language articles. Additional sources were identified from bibliographies of select articles and the manufacturer.

RESULTS

Fondaparinux, a pentasaccharide that selectively inhibits factor Xa, has been reported to have negligible or no cross-reactivity in vitro with HIT antibodies. Thromboembolic treatment and prophylaxis with fondaparinux in patients with HIT has been described. Three cases reported patients who were successfully treated for thromboembolic events with fondaparinux after developing HIT during therapy with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH). Another report showed positive outcomes using fondaparinux for prophylaxis in a patient who had previously developed HIT after receiving UFH. Moreover, 2 case series, one using fondaparinux for prophylaxis in patients with a previous diagnosis of HIT and the other using fondaparinux for treatment in patients who developed HIT while receiving UFH or LMWH, reported normal platelet counts during fondaparinux treatment. Finally, results of a retrospective review demonstrated that fondaparinux prevented thromboembolic events or recurrent thrombocytopenia in patients with a prior HIT diagnosis.

CONCLUSIONS

Limited data support the use of fondaparinux for thromboembolic treatment or prophylaxis in patients with antibody assay-confirmed HIT who do not have a contraindication for fondaparinux use. Randomized controlled trials have not been published; therefore, questions remain regarding efficacy, safety, optimal doses, treatment duration, and incidence of thromboembolic events when fondaparinux is used in this setting. Prospective trials evaluating the efficacy and safety of fondaparinux in this patient population need to be conducted to answer these questions.

OBJECTIVE

We sought to evaluate clinical outcomes of patients with diabetes mellitus in the ACUITY (Acute Catheterization and Urgent Intervention Triage Strategy) trial, overall and by treatment arm.

BACKGROUND

In the ACUITY trial, 13,819 patients with moderate- or high-risk acute coronary syndromes (ACS) were randomized to heparin (unfractionated or enoxaparin) plus glycoprotein IIb/IIIa inhibition (GPI), bivalirudin plus GPI, or bivalirudin monotherapy. Compared with heparin plus GPI, bivalirudin monotherapy resulted in similar protection from ischemic events with less major bleeding. Whether these results apply to patients with diabetes is unknown.

METHODS

We evaluated the impact of diabetes on 30-day net adverse clinical outcomes (composite ischemia [death, myocardial infarction, or unplanned ischemic revascularization] or major bleeding), overall and by antithrombotic strategy.

RESULTS

Diabetes was present in 3,852 randomized patients (27.9%). Compared with nondiabetic patients, diabetic patients had higher 30-day rates of net adverse clinical outcomes (12.9% vs. 10.6%; p < 0.001), composite ischemia (8.7% vs. 7.2%; p = 0.003), and major bleeding (5.7% vs. 4.2%; p < 0.001). Among diabetic patients, compared with heparin plus GPI, bivalirudin plus GPI resulted in similar rates of net adverse clinical outcomes (14.0% vs. 13.8%; p = 0.89), while bivalirudin monotherapy resulted in a similar rate of composite ischemia (7.9% vs. 8.9%; p = 0.39) and less major bleeding (3.7% vs. 7.1%; p < 0.001), yielding fewer net adverse clinical outcomes (10.9% vs. 13.8%; p = 0.02).

CONCLUSIONS

Diabetic patients with ACS managed invasively have higher rates of composite ischemia and major bleeding. Compared with treatment with heparin plus GPI, bivalirudin monotherapy provides similar protection from ischemic events with less major bleeding, resulting in a significant reduction in net adverse clinical outcomes.

BACKGROUND

Central venous catheter (CVC) placement increases the risk of thrombosis and subsequent death in patients with cancer. The objective of this systematic review was to determine the efficacy and safety of anticoagulation in reducing mortality and thromboembolic events in cancer patients with a CVC.

METHODS

The authors searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and ISI the Web of Science databases. They included randomized controlled trials in patients with cancer comparing unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), vitamin K antagonists, fondaparinux, or ximelagatran with no intervention, placebo, or each other. The standard methods of the Cochrane Collaboration were used for the analyses.

RESULTS

Of 3986 identified citations we included 9 randomized clinical trials, none of which evaluated fondaparinux or ximelagatran. Heparin therapy (UFH or LMWH) was associated with a trend toward a reduction in symptomatic deep venous thrombosis (DVT) (relative risk (RR), 0.43; 95% confidence interval (95% CI), 0.18-1.06), but there was no statistically significant effect on mortality (RR, 0.74; 95% CI, 0.40-1.36), infection (RR, 0.91; 95% CI, 0.36-2.28), major bleeding (RR, 0.68; 95% CI, 0.10-4.78), or thrombocytopenia (RR, 0.85; 95% CI, 0.49-1.46). The effect of warfarin on symptomatic DVT also was not statistically significant (RR, 0.62; 95% CI, 0.30-1.27).

CONCLUSIONS

The balance of benefits and downsides of thromboprophylaxis in cancer patients with CVC are uncertain. Clinicians together with their patients must weigh these factors carefully when making decisions regarding thromboprophylaxis.

OBJECTIVE

To compare low molecular weight heparin (LMWH), specifically dalteparin, to unfractionated heparin (UFH) for the treatment of antiphospholipid antibody syndrome (APS) in pregnancy.

METHODS

In a tertiary referral centre, 28 women met the 1999 International Consensus Criteria for APS, based on their obstetrical history and APS serology. The women were randomized, using a random numbers table with blocks of 12, to receive either prophylactic dosing of dalteparin or UFH starting either preconceptionally or early in pregnancy. All women also received low-dose acetylsalicylic acid, started preconceptionally. The primary outcome was a live birth. The secondary outcomes were maternal and fetal complications.

RESULTS

Of the 14 women who received the LMWH, dalteparin, and the 14 women who received UFH, 1 woman in each group did not conceive. Nine of the 13 women (69%) given dalteparin had a successful pregnancy (95% confidence interval [CI], 39-91%), compared to 4 out of the 13 women (31%) in the UFH group (95% CI, 9-61%). Nine women in total had spinal or epidural anaesthesia, and there were no complications overall.

CONCLUSIONS

Dalteparin may be an effective alternative to UFH for treatment of APS in pregnancy. A multicentre randomized trial is needed to determine benefit-to-risk ratios for the use of dalteparin and UFH to treat this high-risk obstetrical condition. Pharmacokinetic and pharmacodynamic studies are also recommended to maximize therapeutic response and minimize toxicity.

OBJECTIVE

Culture media for mesenchymal stromal cells (MSCs) are generally supplemented with fetal bovine serum. Human platelet lysate (hPL) has been proven to be a very effective alternative without the risk of xenogeneic infections or immune reactions. In contrast to fetal bovine serum, hPL comprises plasma, and anticoagulants-usually unfractionated heparin (UFH)-need to be added to prevent gel formation.

METHODS

Cultures of MSCs in hPL media with various concentrations of UFH and enoxaparin, a low-molecular-weight heparin (LMWH), were systematically compared with regard to proliferation, fibroblastoid colony-forming unit frequency, immunophenotype and in vitro differentiation.

RESULTS

At least 0.61 IU/mL UFH or 0.024 mg/mL LMWH was necessary for reliable prevention of coagulation of hPL pools used in this study. Higher concentrations impaired cellular proliferation in a dose-dependent manner even without benzyl alcohol, which is commonly added to heparins as a bacteriostatic agent. Colony-forming unit frequency was also reduced at higher heparin concentrations, particularly with LMWH, whereas no significant effect was observed on cellular morphology or immunophenotype. High concentrations of heparins reduced the in vitro differentiation toward adipogenic and osteogenic lineages.

CONCLUSIONS

Heparin concentration is critical for culture of MSCs in hPL media; this is of particular relevance for cellular therapy where cell culture procedures need to be optimized and standardized.

Heparin and heparan sulfate (HS) are important pharmaceutical targets because they bind a large number of proteins, including growth factors and cytokines, mediating many biological processes. Because of their biological significance and complexity, there is a need for development of rapid and sensitive analytical techniques for the characterization and compositional analysis of heparin and HS at the disaccharide level, as well as for the structure elucidation of larger glycosaminoglycan (GAG) sequences important for protein binding. In this work, we present a rapid method for analysis of disaccharide composition using reversed-phase ion-pairing ultraperformance liquid chromatography coupled with electrospray time-of-flight mass spectrometry ((RPIP)-UPLC-MS). Heparin disaccharide standards were eluted in less than 5 min. The method was used to determine the constituents of GAGs from unfractionated heparin/HS from various bovine and porcine tissues, and the results were compared with literature values.

The in vitro effect of unfractionated heparin and dermatan sulfate, as well as oligo-heparin and oligo-dermatan sulfate, on human PMN function was investigated. Superoxide anion generation in fMLP-stimulated PMN was dose-dependently reduced by heparin and oligo-heparin, while DS and oligo-DS lacked inhibitory activity. FMLP-stimulated PMN adhesion to endothelial cells was reduced to a similar extent by both heparin and oligo-heparin, but not by DS and oligo-DS. On the other hand, none of the compounds affected the adhesion of unstimulated PMN to either IL-1- or PMA-activated endothelial cells. Heparin and oligo-heparin also inhibited the homotypic aggregation of fMLP-stimulated PMN. As reported, coincubation of platelets with fMLP-stimulated PMN resulted in platelet activation, a process mainly mediated by the PMN-derived serine protease cathepsin G. Both heparin and DS, as well as their oligo-derivatives, reduced platelet activation induced by either fMLP-stimulated PMN or purified leukocytic cathepsin G. Finally, besides cathepsin G, also the activity of beta-glucuronidase and lysozyme released by stimulated PMN were reduced by heparin, oligo-heparin and DS. These data support the hypothesis that heparin and other GAGs may exert an antiinflammatory role.

Traumatic brain injury (TBI) patients are known to be at high risk for venous thromboembolic events (VTEs). The Brain Trauma Foundation Guidelines (2007) state that low-molecular-weight heparin or unfractionated heparin should be used to prevent VTE complications, but suggest that there is an increased risk of expansion of intracranial hemorrhages (ICH) with VTE prophylaxis. In addition, it is unclear which treatment regimen (i.e., medication, dose, and timing) provides the best risk:benefit ratio in TBI patients. We reviewed all moderate-to-severe TBI patients admitted over a 5-year period to: (1) examine the occurrence of VTEs and their timing; (2) examine the symptomatic expansion of ICH while on VTE prophylaxis; and (3) compare the efficacy of two prophylactic agents: enoxaparin and dalteparin. Two-hundred eighty-seven patients were included. VTE prophylaxis was started 48-72 h post-trauma in all individuals who had no confounding coagulopathy, when two consecutive computed tomography (CT) scans revealed hemorrhage stability. VTEs occurred in 7.3% of treated patients, mostly within 2 weeks after trauma. Proximal VTEs occurred in 3.1% of treated patients. No significant difference in VTE rates was seen between enoxaparin (7.0%) and dalteparin (7.5%; p = 0.868). Moreover, the group treated with dalteparin was more severely injured (higher Injury Severity Score [p = 0.002]), had lower Glasgow Coma Scale (GCS) scores (p = 0.003), and had more inferior vena cava (IVC) filters placed (p = 0.007). The two groups did not show significant differences in the development of VTE when controlled for ISS and IVC filters (p = 0.819). Importantly, only one patient suffered a symptomatic expansion of ICH while on VTE prophylaxis, at 15 days post-trauma. These results suggest that current regimens of VTE prophylaxis used in our TBI population provide a relatively high level of protection against VTEs, and an extremely low risk of expanding ICH. They also suggest that there was no difference in VTE between dalteparin- and enoxaparin-treated patients.

A technique has been developed to monitor the development of thrombin in freshly collected whole blood in the absence of anticoagulants. It is based on the centrifugal separation of the cellular components from subsamples of blood drawn from non-anticoagulated clotting whole blood which are diluted in buffer containing a chromogenic substrate. It is shown that the burst of thrombin generation after triggering coagulation with trace amounts of tissue thromboplastin occurs sooner in non-anticoagulated whole blood than in citrated whole blood. Heparin is shown to prolong the lag-time of thrombin generation more in native blood than in recalcified citrated blood. It is also demonstrated that intake of 500 mg of aspirin significantly delays and inhibits thrombin generation in non-anticoagulated, thromboplastin triggered whole blood, whereas it has no effect on the coagulation in citrated plasma. The effect of aspirin intake on thrombin generation in blood is roughly equal to that of 0.03 U/ml of unfractionated heparin. This demonstrates that platelet reactions and the coagulation system are closely linked processes. It further lends support to the hypothesis that inhibition of thrombin generation is a common denominator of antithrombotic therapy.

Heparin-induced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to low-molecular weight heparin. In this comprehensive review, the authors highlight heparin-induced thrombocytopenia's risk factors, clinical presentation, pathophysiology, diagnostic principles, and treatment. The authors place special emphasis on the management of patients requiring procedures using cardiopulmonary bypass or interventions in the catheterization laboratory. Clinical vigilance of this disease process is important to ensure its recognition, diagnosis, and treatment. Misdiagnosis of the syndrome, as well as misunderstanding of the disease process, continues to contribute to its morbidity and mortality.

Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse effect of heparin that is important because of its relatively high frequency and its strong association with paradoxic venous and arterial thrombosis. As confirmatory laboratory assays are not always immediately available, physicians usually must make initial diagnostic and treatment decisions based on the clinical presentation alone. Three characteristic features of HIT can be helpful in distinguishing it from other causes of thrombocytopenia: (1) timing of the onset of thrombocytopenia, namely, a platelet count decrease that begins between days 5 and 8 (inclusive) of beginning heparin treatment; (2) mild to moderate severity of the thrombocytopenia, with platelet counts only rarely less than 15 x 10(9)/L; and (3) the development of large-vessel venous or arterial thrombosis in association with thrombocytopenia, or any of a number of unusual characteristic sequelae of HIT (warfarin-associated venous limb gangrene, bilateral adrenal hemorrhagic infarction, heparin-induced skin lesions, or acute systemic reactions following intravenous heparin bolus). In contrast to other drug-induced immune thrombocytopenia syndromes, HIT rarely is associated with bleeding. HIT is relatively common, occurring in as many as 3% of patients who receive unfractionated (UF) heparin for 2 weeks. Between 30% and 75% of patients with HIT develop thrombosis; thus, about 1% of patients who receive a course of heparin develop HIT-associated thrombosis. The observation that HIT is less likely to occur with low-molecular-weight heparin (LMWH) suggests that HIT ultimately may be preventable.

Low-molecular weight heparins (LMWHs) have been shown to be as safe and effective as unfractionated heparin (UFH) for the treatment of acute venous thrombosis and non-life-threatening pulmonary embolism. Different reports have shown that LMWHs may also be used to treat patients with unstable angina or non-Q-wave infarction. The safety of LMWHs used at therapeutic dose has been widely studied in pivotal clinical trials and analysed in several meta-analyses. However, despite the wide development and use of LMWHs, several issues regarding the safety and optimal use of LMWHs remain unanswered. The main adverse effect of LMWHs is bleeding and it is uncertain whether a weight-adjusted dosage regimen without laboratory monitoring can be used in patients with a high risk of bleeding, such as patients with renal failure, elderly patients, obese patients or pregnant women. These patients are usually excluded from clinical trials and only a few studies, not sufficiently powered to estimate efficacy and safety, have been carried out in these special populations. Most of the available data comes from pharmacokinetic or population pharmacodynamic studies or clinical reports. Results in patients with renal impairment who are not undergoing haemodialysis suggest that a reduction in calculated creatinine clearance levels is associated with an increased risk of accumulation of anti-Xa activity, the extent of which differs depending on the individual LMWH and the extent to which the compound is cleared by the kidney. The limited data available regarding the use of therapeutic doses of LMWHs in obese patients suggest that there is no need to cap the dose at a maximal allowable dose. Long-term (3-month) treatment with LMWHs appears to be as effective and safe as oral anticoagulant therapy for the treatment of venous thromboembolism. It appears that each LMWH is a distinct compound with unique pharmacokinetic and pharmacodynamic profiles. Until more data are available regarding these special populations, periodic monitoring of anti-Xa activity levels may be recommended to detect accumulation and/or an overdose and minimise the bleeding risk. The non-haemorrhagic adverse effects of the LMWHs include heparin-induced thrombocytopenia (HIT) and osteoporosis. The incidence of HIT appears to be lower with LMWHs than with UFH; there is currently not enough data to compare the frequency of HIT between the various LMWHs. LMWHs also appear to carry a lower risk of causing osteoporosis than UFH. In conclusion, studies that include special population patients are required to make conclusive recommendations concerning the safety and monitoring of the different LMWHs.

Standard venous thromboembolic event (VTE) treatment practices including the use of intravenous unfractionated heparin (UFH) for initial anticoagulation, oral warfarin for chronic anticoagulation, and the prescription of only 3 to 6 months total therapy may not be optimal in the setting of active cancer and ongoing anti-cancer therapy. Challenges of VTE management in cancer patients include heparin resistance due to excess circulating acute-phase proteins, increased recurrence rates during and following standard-intensity warfarin therapy, limited venous access to support therapeutic monitoring, and anticoagulation intensity-independent increased bleeding rates during anticoagulation. Bleeding during anticoagulation is of particular concern in the treatment of cancer patients with disease- or chemotherapy-related thrombocytopenia, central nervous system involvement, or recent invasive procedures. Low-molecular weight heparins (LMWH) have been shown to be at least as effective and safe for initial anticoagulation compared with UFH in persons with acute VTE and have gained popularity in the setting of VTE in cancer. LMWHs have the advantage of less non-specific protein binding, subcutaneous weight-based dosing without the need for monitoring in most cases, and probably less heparin-induced thrombocytopenia. Recent trials have demonstrated efficacy superiority of select LMWHs in place of oral warfarin for long-term anticoagulation in the cancer patient. The potential for anti-tumor effects and a survival advantage associated with select classes of anticoagulant agents is actively being investigated.

BACKGROUND

Enhanced thrombin activity has been associated with acute and long-term complications following balloon angioplasty (percutaneous transluminal coronary angioplasty (PTCA). We evaluated, in a 2-to-1 randomized, double-blind trial, the effects of recombinant hirudin, CGP 39 393, relative to unfractionated sodium heparin on periprocedural events, bleeding, early angiographic outcome, and coagulation in 113 patients with stable angina undergoing PTCA.

RESULTS

Prior to PTCA, 20 mg CGP 39 393 was administered as a bolus, followed by continuous infusion at a rate of 0.16 mg.kg-1 x h-1, or 10,000 IU sodium heparin was administered as a bolus and continued at a rate of 12 IU.kg-1 x h-1 for 24 hours. Infusion was adjusted to activated partial thromboplastin time (APTT) levels. ST segment was monitored for 24 hours, and angiograms were analyzed with quantitative technique (QCA). In 74 CGP 39 393- and 39 heparin-treated patients, 132 lesions were dilated. Myocardial infarction and/or emergency coronary bypass surgery occurred in 1 (1.4%) CGP 39 393 patient compared with 4 (10.3%) heparin patients (relative risk, 7.6; 95% confidence interval, 0.9, 65.6). At 24 hours, complete perfusion was present in 91% heparin and 100% CGP 39 393 patients. Significant ST segment displacement was found in 11% of heparin versus 4% of CGP 39 393 subjects. Bleeding occurred only at the puncture site in 4 CGP 39 393-treated patients. QCA did not reveal significant differences between the groups. APTT values were more often in the target range and more stable in CGP 39 393 patients. Levels of thrombin-antithrombin III complexes, prothrombin fragment F1+2, and fibrinopeptide A indicated that CGP 39 393 was an effective inhibitor of thrombin activity.

CONCLUSIONS

CGP 39 393 can safely be administered to patients undergoing elective PTCA for stable anginal symptoms and may have a more favorable anticoagulant profile than heparin.

Immune heparin-induced thrombocytopenia (HIT) is a relevant adverse drug reaction consisting in a hypercoagulable state caused by an anticoagulant agent. The incidence is approximately 6.5% in patients receiving unfractionated heparin after orthopedic surgery, and is equal to or lower than 1% in other settings. HIT occurrence is a function of heparin type, duration of heparin administration, patient population, and gender. The pathogenesis is due to an antibody response to the complex heparin/platelet factor 4 in most cases, with secondary activation of platelets and coagulation, and finally increased thrombin generation. Thrombocytopenia, venous or arterial thrombosis, heparin-induced skin necrosis, adrenal hemorrhage, and transient amnesia can characterize the clinical course of HIT. Platelet monitoring in patients receiving heparin is indicated to early detect HIT. A thrombotic event can be the first manifestation of HIT. Laboratory demonstration of heparin-dependent platelet activation confirms the clinical diagnosis; antigenic or functional assays are available. Once HIT is highly likely or confirmed serologically, immediate heparin cessation is mandatory and an alternative therapeutic anticoagulant is needed due to the high risk (or the presence) of thrombotic events. The available nonheparin anticoagulants aim to reduce thrombin generation. Lepirudin, argatroban, and bivalirudin (direct thrombin inhibitors) and danaparoid and fondaparinux (factor Xa inhibitors) represent the current treatment options for HIT. Vitamin K antagonists can be used safely only after a stable platelet count has been obtained.

Heparin and various heparin fractions were separated according to differences in molecular weight or affinity for antithrombin III and used for the inhibition of Plasmodium falciparum merozoite invasion of red blood cells in vitro. No variation in sensitivity to heparin was found among the four strains of P. falciparum tested; all required approximately 5 micrograms/ml (0.5 U/ml) of heparin for 50% inhibition of invasion. The most efficient fraction of heparin was the one with low affinity for antithrombin III. Its 50% inhibition concentration was 1 microgram/ml, indicating that it was more efficient than unfractionated heparin and other heparin fractions. The effect of heparin was reversible, since washing of heparin-treated cultures containing mainly schizonts showed no inhibition of merozoite invasion. The results suggest that a heparin fraction with no anticoagulant effect might be useful in the treatment of patients with falciparum malaria.

Ulcerative colitis is a chronic inflammatory bowel disorder of unknown etiology. Treatment of flare-ups is based on mesalamine and steroids. Treatment of moderate to severe ulcerative colitis with high-dose heparin and low-molecular-weight heparin was reported. The mechanism was assumed to be a combination of anti-coagulant and anti-inflammatory effects. Low-molecular-weight heparin is better and safer than unfractionated heparin. Studies of low-dose low-molecular-weight heparin in experimental models of inflammation and in inflammatory diseases demonstrated a beneficial effect. Our aim in this study was to evaluate the effect of low-dose, low-molecular-weight heparin in active ulcerative colitis. Twelve patients with flare-ups of colitis were prospectively enrolled. Subcutaneous injections of 5-mg enoxaparin were administered at weekly intervals for 12 weeks. Mesalamine doses remained unchanged. Clinical, laboratory, endoscopic, histologic, and quality-of-life scores were evaluated at the beginning and end of the study. Ten patients completed the study. Mean age was 40.1; the female-male ratio was 7:3. Mean Mayo scores were 9.0 +/- 0.94 at baseline and 3.4 +/- 2.0 at the end of the study (P = 0.0001). Endoscopic scores decreased from 2.2 +/- 0.4 to 1.2 +/- 1.0 (P = 0.049) and in 7 of 10 patients extent of disease shortened. A significant increase in IBDQL scores from 135.7 +/- 37.17 to 179.6 +/- 45.15 points was demonstrated (P = 0.0117). Adverse events were one hospitalization due to abdominal pain, arthralgia (1), transient peripheral edema (1), and elevation of alkaline phosphatase (1). During follow-up, one patient required colectomy and another experienced an exacerbation. In conclusion, low-dose low-molecular-weight heparin once a week, combined with mesalamine, may be an effective therapy for active ulcerative colitis. It may delay or preclude the need for steroid treatment. Controlled studies to evaluate efficacy are needed.

BACKGROUND

In medically ill patients, no contemporary double-blind head-to-head evaluation of low molecular weight heparin vs. unfractionated heparin (UFH) for the prevention of venous thromboembolic events is available.

OBJECTIVE

To compare the efficacy and safety of certoparin with those of UFH.

METHODS

In this double-blind, randomized, controlled trial, acutely ill, non-surgical patients aged>> or = 70 years were randomized to certoparin (3000 U of anti-factor Xa once daily) or to UFH (5000 IU t.i.d.). The primary endpoint was the composite of proximal deep vein thrombosis as assessed by bilateral compression ultrasonography, symptomatic non-fatal pulmonary embolism and venous thromboembolism-related death, and was assessed by a blinded central adjudication committee. Non-inferiority margins were set at 1.8 for the odds ratio (OR) and 3.45% for the absolute difference.

RESULTS

Three thousand two hundred and thirty-nine patients aged 78.8 + or - 6.3 years were treated for 9.1 + or - 3.4 days. The incidence of the primary endpoint was 3.94% in the certoparin group and 4.52% in the UFH group, with a difference in proportions of - 0.59% [95% confidence interval (CI) -2.09 to 0.92; P < 0.0001 for non-inferiority], and an OR of 0.87 (95% CI 0.60-1.26; P = 0.0001 for non-inferiority). Major bleeding occurred in 0.43% of certoparin-treated patients and 0.62% of UFH-treated patients (OR 0.69; 95% CI 0.26-1.83). Any bleeding occurred at 3.20% in certoparin-treated patients vs. 4.58% in UFH-treated patients (OR 0.69; 95% CI 0.48-0.99; P < 0.05), and 5.73% of certoparin-treated patients and 6.63% of UFH-treated patients experienced serious adverse events. All-cause mortality was 1.27% in certoparin-treated patients and 1.36% in UFH-treated patients.

CONCLUSIONS

In acutely ill, non-surgical elderly patients, thromboprophylaxis with certoparin (3000 U of anti-FXa once daily) was non-inferior to 5000 IU of UFH t.i.d., with a favorable safety profile.