[HIP FRACTURE SURGERY DELAY IN PATIENTS TREATED WITH ORAL ANTICOAGULANTS: RESULTS FROM SHEBA MEDICAL CENTER].

BACKGROUND: Hip fractures (HF) are a major cause of morbidity and mortality in the elderly population. Many factors are associated with HF post-operative prognosis, among them the admission to operation time (AOT) is a major factor. Delayed surgery (> 48 hours) is associated with increased morbidity and mortality. The use of anti-coagulants (OAC) often leads to surgery delay to prevent possible surgical bleeding. OBJECTIVES: To test the association between the use of OAC and AOT. METHODS: The study was a retrospective cohort of consecutive patients above 65 years of age admitted and operated for hip fracture at the Sheba Medical Center between the years 2014-2018. We compared AOT between OAC treated and non-treated patients. We conducted multi-variable analysis to examine the effect of OAC on AOT. RESULTS: Overall, 1013 case patients were studied, among them 151 were treated with OAC (research group) and 865 patients without any anti-coagulation treatment (control group). Surgery delay over 48 hours was observed in 24.6% OAC treated patients compared to 12% in the non-treatment group (p=0.0001). Median AOT was 32 hours compared to 24.6 hours in treated vs non-treated patients, respectively, p=0.0001. Apixaban is the only drug found not to prolong AOT. In multivariate analysis OAC therapy was the only significant cause for surgical delay. CONCLUSIONS: Patients with HF treated with anti-coagulants are experiencing delayed surgery compared to non-treated patients.

Venous Thromboembolism Among Patients With Inflammatory Bowel Diseases is Not Related to Increased Thrombophilia: A Case-Control Study.

GOAL: The aim was to assess whether thrombophilia significantly contributes to the risk of venous thromboembolic events (VTEs) in patients with inflammatory bowel disease (IBD). BACKGROUND: Patients with IBD have a high risk of VTE. The underlying mechanism has been only partially defined. METHODS: A case-control study in adults with IBD and an episode of VTE (IBD-VTE) were matched and compared with non-IBD patients with a VTE (non-IBD-VTE). The study population was comprised of patients seen in 2 tertiary medical centers in Israel between 2000 and 2013. Characteristics of IBD and risk factors for VTE were retrieved from medical charts, and a comprehensive thrombophilia panel was completed in all patients. RESULTS: Forty-four IBD-VTE cases (27 Crohn's disease) were matched with 127 non-IBD-VTE controls. The majority of VTE had a clear etiology and were considered provoked events. Provoked and unprovoked VTE rates were not different between the 2 groups. Likewise, thrombophilia rates were similar among patients with IBD-VTE and controls (40.9% vs. 53.5%, respectively, P=0.14). However, among patients with unprovoked VTE, thrombophilia rates were significantly lower in the IBD-VTE group compared with controls (42.1% vs. 70.7%, respectively, P=0.03). Among patients with IBD-VTE, an unprovoked event, and negative thrombophilia, 77% had active inflammation at the time of VTE. CONCLUSION: Thrombophilia rates are similar among patients with IBD-VTE and controls but are less common among patients with unprovoked IBD-VTE. This finding suggests that either inflammation or other novel pathways drive VTE in patients with IBD.

Pulmonary Embolism in Cancer Patients: A Review.

BACKGROUND: Pulmonary embolism (PE) is very common in cancer patients and is a marker of increased mortality in these patients. Treatment is associated with increased rates of recurrent thrombosis and bleeding and has undergone significant change in the last years with the increasing use of direct oral anticoagulants. Diagnosis of PE and risk stratification is possible with minor changes to existing risk scores. Thrombolytic therapy should be considered in appropriate patients.

Emicizumab prophylaxis in haemophilia patients older than 50 years with cardiovascular risk factors: Real-world data.

INTRODUCTION: Emicizumab (Hemlibra™) is approved for prophylaxis of Haemophilia A (HA) patients with and without inhibitors. However, real-world data on emicizumab use in the elderly HA patients with concomitant cardiovascular risk factors are lacking. AIM: To evaluate the safety and efficacy of emicizumab in a real-world cohort of elderly HA patients. METHODS: A prospective longitudinal observational study on HA patients over 50 years old treated, followed and monitored during emicizumab prophylaxis was conducted. We documented any bleeding or adverse events and collected plasma samples for emicizumab levels, aPTT and thrombin generation (TG). RESULTS: Seventeen HA patients (2 with inhibitor), whose median age was 62.4 years (range: 51.5-77.1) composed the cohort, including 9/17 with multiple cardiovascular risk factors (high risk group). Seven patients had chronic HIV infection. The median follow-up of our cohort was 400 days (range 89-805, IQR 211-479 days). The median annualized bleeding rate (ABR) significantly decreased for all patients. Among patients who displayed significant bleeding tendencies, emicizumab steady state levels as well as TG were lower as compared with the group. The ABR of four patients concomitantly treated by antiplatelet agents was significantly higher compared with the rest of the cohort. Neither thrombosis nor thrombotic microangiopathy (TMA) was encountered. CONCLUSIONS: Emicizumab prophylaxis for HA patients older than 50 years including those with cardiovascular risk factors was well tolerated. As lower emicizumab and TG levels were observed among bleeding patients, we suggest that monitoring laboratory assays could be of value within this age group.

Emicizumab prophylaxis: Prospective longitudinal real-world follow-up and monitoring.

INTRODUCTION: Real-world data on prophylaxis of severe haemophilia A (HA) patients treated by emicizumab are scarce. AIM: To study the efficacy and safety of longitudinal emicizumab prophylaxis and assess laboratory monitoring correlations in a large patient cohort. METHODS: HA patients with and without FVIII inhibitors, initiating emicizumab prophylaxis, were prospectively enrolled. Bleeding, adverse events and surgeries were documented. FVIII inhibitors, emicizumab levels and thrombin generation (TG) were sequentially measured. RESULTS: A total of 107 patients, including 58 children (whose median (IQR) age was 6 (1-11) years) with severe HA, composed the study cohort. Twenty-nine per cent (31/107) of our HA patients had FVIII inhibitors. Patients were followed for a median of 67 weeks (up to 144 weeks). Fifty-three patients, whose median follow-up was 53 weeks, experienced zero bleeds. Most bleeds (94%) among children were trauma-related, whereas 61% of adults sustained spontaneous joint bleeds. Four patients experienced major bleeds, with a fatal outcome in one infant, who also presented with central venous line thrombosis. No other serious adverse events were encountered. Seven patients have decided to stop emicizumab treatment for various reasons. Emicizumab plasma levels increased after emicizumab prophylaxis initiation, and values were maintained during follow-up, in all but one patient, suspected of anti-drug antibodies. A significant reduction of FVIII inhibitor levels was noted among inhibitor patients. TG was increased and sustained yet could not prognosticate bleeding risk. CONCLUSION: Emicizumab prophylaxis was mostly well tolerated, although 50% of patients experienced breakthrough bleeds. Routine TG monitoring is not obligatory, and further studies are warranted in selected patient populations.

Pulmonary Endarterectomy Surgery for Chronic Thromboembolic Pulmonary Hypertension: A Small-Volume National Referral Center Experience.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare, distinct pulmonary vascular disease, which is caused by chronic obstruction of major pulmonary arteries. CTEPH can be cured by pulmonary endarterectomy (PEA). PEA for CTEPH is a challenging procedure, and patient selection and the perioperative management are complex, requiring significant experience. OBJECTIVES: To describe the establishment of a national CTEPH-PEA center in Israel and present results of surgery. METHODS: In this study, we reviewed the outcomes of PEA in a national referral, multi-disciplinary center for CTEPH-PEA. The center was established by collaborating with a high-volume center in Europe. A multidisciplinary team from our hospital (pulmonary hypertension specialist, cardiac surgeon, cardiac anesthesiologist and cardiac surgery intensivist was trained under the guidance of an experienced team from the European center. RESULTS: A total of 38 PEA procedures were performed between 2008 and 2018. We included 28 cases in this analysis for which long-term follow-up data were available. There were two hospital deaths (7%). At follow-up, median New York Heart Association (NYHA) class improved from III to I (P < 0.0001), median systolic pulmonary pressure decreased from 64 mmHg to 26 mmHg (P < 0.0001), and significant improvements were seen in right ventricular function and exercise capacity. CONCLUSIONS: A national center for performance of a rare and complex surgical procedure can be successfully established by collaboration with a high-volume center and by training a dedicated multidisciplinary team.

[PEDIATRIC VENOUS THROMBOEMBOLISM - A COHORT STUDY IN A TERTIARY CENTER].

INTRODUCTION: Deep Venous Thrombosis (DVT) is rare among children, yet may yield high morbidity and mortality. Due to the limited data regarding pediatric DVT, its management has been adopted from adults' protocols. Recent research reported associations of DVT and strokes with genetic thrombophilia, especially in the presence of transient risk factors (e.g.: hospitalization, malignancy, central venous lines…). AIMS: To evaluate the influence of risk factors within our pediatric DVT cohort of a tertiary center upon treatment and prognosis. METHODS: Retrospective analysis of prospectively collected data at the Sheba Medical Center. RESULTS: During the period 2014-2017, 76 out of 150 cases of acute DVT diagnosed at our center were fully followed. Upper extremity DVT was most commonly observed. Malignancy and a central venous line (CVL) were the most abundant risk factors. Genetic thrombophilia was diagnosed in one third of the cases. The majority of patients were treated with low molecular weight heparin for at least 3 months and 13% continued prolonged anti-coagulation treatment. Neither thrombophilia nor cancer affected the outcome. DISCUSSION: Our results confirm previously published data indicating that malignancy and CVL are the most common risk factors associated with DVT in children, making the upper extremity the most common location of thrombosis. Neither the type of cancer nor genetic thrombophilia was found to be associated with treatment outcome, but they did influence the treatment duration. Risk factors influence the pathogenesis of DVT and influence the duration of treatment.

A novel approach using ancillary tests to guide treatment of Glanzmann thrombasthenia patients undergoing surgical procedures.

BACKGROUND: Glanzmann thrombasthenia (GT) is a disorder of platelet function. Standard therapy includes platelet transfusions, which may be hampered by antiplatelet antibodies. AIMS: To assess potential correlation between bleeding and number of active platelets in GT patients undergoing surgery. Clinical peri- operative patients' hemostasis was compared with flow cytometry analysis (FC), and whole blood clot formation. METHODS: GT patients undergoing surgery were included. Blood counts, platelet activation studies, FC and rotational thromboelastography (ROTEM) were performed as ancillary tests to estimate the effectiveness of treatment. RESULTS: A total of 4 GT patients undergoing 5 surgeries were included. Consecutive FC analysis following platelet transfusions showed gradual decrease of donor platelets with a nadir of 3280 platelets in patients who experienced no post procedural bleeding following minor procedures. After major surgery, bleeding occurred when donor platelets decreased to 2600-4280. Decline in donor platelets was associated with reduced clot firmness as noted by ROTEM. CONCLUSION: Results suggest that very low number of active donor platelets may suffice to achieve proper hemostasis in certain procedures. Our study points to the potential role of consecutive FC examinations to demonstrate the number of donor platelets as an ancillary tool for decision making in GT patients undergoing surgery.

The impact of genetic and environmental factors on homocysteine levels in preterm neonates.

BACKGROUND: Hyperhomocysteinemia may be associated with vascular complications in adults. Whereas pediatric thrombosis risk peaks in neonates, data on homocysteine (Hcy) levels assessed in term and preterm infants during the perinatal period are scarce. In the present study, we aimed to establish Hcy reference values for preterm infants and study their potential associations with the early post-natal health status. Plasma Hcy and hematocrit levels and MTHFR polymorphisms (C677T and A1298C substitution) were studied in a large cohort of preterm infants in a tertiary referral medical center during an 18-month period. Data were collected on maternal history and delivery as well as on post-natal complications. RESULTS: The study cohort included 167 infants whose mean gestational age was 30.98 ± 2.34 weeks (range: 26-36 weeks), mean birth weight 1327.6 ± 327 g, and mean Hcy level 7.99 ± 3.27 (range: 2.2-21.2) µmol/L. Maternal intake of folic acid was inversely associated with the babies' Hcy levels (P = 0.0001). Increased Hcy levels positively correlated with birth weight, gestational age (P < 0.005), total number of pregnancies (P = 0.012), and presence of MTHFR polymorphism. Higher Hcy levels were associated with feeding (P = 0.008), especially total parenteral nutrition (P = 0.0001). There was no correlation between Hcy levels and any vascular post-natal complications. CONCLUSIONS: During their post-natal hospitalization, preterm infants may have relatively high, that is, within the adult normal range, Hcy levels which are influenced by genetic and environmental factors. Despite the fact that no correlation was found between Hcy levels and post-natal complications, these associations should be further studied.

Percutaneous coronary intervention in patients with haemophilia presenting with acute coronary syndrome: an interventional dilemma: case series, review of the literature, and tips for management.

Since the introduction of clotting factor concentrates over 50 years ago the life expectancy of patients with hemophilia (PWH) has increased to over 70 years. Consequently, diseases of the ageing population, including coronary artery disease, are increasingly being encountered. These patients present a unique therapeutic problem due to their greatly increased bleeding risk. Randomized controlled studies specific to PWH are lacking, emphasizing the need for case series. We present three cases of acute coronary syndrome in PWH who underwent urgent percutaneous coronary intervention at our institution, and summarize the available literature on the topic. We describe their management and outcome and provide points to consider when treating these complex patients.

[Prevention of venous thromboembolism--what have we learned and how well are we doing?].

INTRODUCTION: In recent years, awareness regarding thromboprophylactic treatment for hospitalized patients at risk has grown significantly. Large trials incorporating thousands of patients published in recent years have proved that prophylactic treatment is effective and reduces the rates of hospital-acquired venous thromboembolism. PATIENTS AND METHODS: Two cross-sectional studies held in medical and general surgery wards have found that, similar to other medical centers worldwide, hospitalized patients are older, have many medical problems, and suffer from reduced mobility. These risk factors exist in approximately half of the patients in medical wards and should lead to prophylactic therapy, however only 22% of such high risk patients actually received treatment. In non-operated general surgery patients, the rate of prophylaxis use is even lower. In patients after surgery, the rate of use is higher but not optimal. Although in a survey most of the directors in medical and surgical wards claimed that prophylaxis is an important issue, and that they support prophylaxis regimens, the rate of prophylaxis was generally low and unsatisfying. CONCLUSION: Patients hospitalized at medical and surgical wards are at risk of acquiring venous thromboembolism, however rates of prophylaxis are low. Methods to improve prophylaxis rates should be adopted.

Long-term safety and efficacy of rIX-FP prophylaxis with extended dosing intervals up to 21 days in adults/adolescents with hemophilia B.

BACKGROUND: An international, multicenter extension study evaluated recombinant fusion protein linking recombinant coagulation factor IX (FIX) with recombinant human albumin (rIX-FP) in hemophilia B (FIX ≤ 2%) patients previously enrolled in a phase III study or who initiated rIX-FP prophylaxis following surgery. OBJECTIVES: To investigate the long-term safety and efficacy of rIX-FP prophylaxis in adult previously treated patients (PTPs) with hemophilia B. METHODS: Male PTPs were treated with a 7- (35-50 IU/kg), 10- or 14-day regimen (50-75 IU/kg). Patients ≥18 years who were well-controlled on a 14-day regimen for ≥6 months could switch to a 21-day regimen (100 IU/kg). RESULTS: A total of 59 patients (aged 13-63 years) participated in the study. Following a single dose of 100 IU/kg rIX-FP, in patients eligible for the 21-day regimen, the mean terminal half-life was 143.2 hours. Mean steady-state FIX trough activity levels ranged from 22% with the 7-day regimen to 7.6% with the 21-day regimen. Median (Q1, Q3) annualized spontaneous bleeding rates were 0.00 (0.00, 1.67), 0.28 (0.00, 1.10), 0.37 (0.00, 1.68), and 0.00 (0.00, 0.45) for the 7-, 10-, 14-, and 21-day regimens, respectively. Comparable efficacy was demonstrated for both the 14- and 21-day regimens compared to the 7-day regimen. Overall, 96.5% of bleeding episodes were treated successfully with 1 to 2 rIX-FP infusions. No patients developed an inhibitor and treatment was well tolerated. CONCLUSIONS: rIX-FP extended interval prophylaxis provides dosing flexibility and, in selected patients, a 21-day regimen may provide an alternative option to minimize treatment burden and individualize treatment.

Impact of inherited thrombophilia on venous thromboembolism in children: a systematic review and meta-analysis of observational studies.

BACKGROUND: The aim of the present study was to estimate the impact of inherited thrombophilia (IT) on the risk of venous thromboembolism (VTE) onset and recurrence in children by a meta-analysis of published observational studies. METHODS AND RESULTS: A systematic search of electronic databases (Medline, EMBASE, OVID, Web of Science, The Cochrane Library) for studies published from 1970 to 2007 was conducted using key words in combination as both MeSH terms and text words. Citations were independently screened by 2 authors, and those meeting the inclusion criteria defined a priori were retained. Data on year of publication, study design, country of origin, number of patients/controls, ethnicity, VTE type, and frequency of recurrence were abstracted. Heterogeneity across studies was evaluated, and summary odds ratios and 95% CIs were calculated with both fixed-effects and random-effects models. Thirty-five of 50 studies met inclusion criteria. No significant heterogeneity was discerned across studies. Although >70% of patients had at least 1 clinical risk factor for VTE, a statistically significant association with VTE onset was demonstrated for each IT trait evaluated (and for combined IT traits), with summary odds ratios ranging from 2.63 (95% CI, 1.61 to 4.29) for the factor II variant to 9.44 (95% CI, 3.34 to 26.66) for antithrombin deficiency. Furthermore, a significant association with recurrent VTE was found for all IT traits except the factor V variant and elevated lipoprotein(a). CONCLUSIONS: The present meta-analysis indicates that detection of IT is clinically meaningful in children with, or at risk for, VTE and underscores the importance of pediatric thrombophilia screening programs.

Factor v Leiden and antiphospholipid antibodies in either mothers or infants increase the risk for perinatal arterial ischemic stroke.

BACKGROUND AND PURPOSE: The objective was to investigate the role of infant and maternal thrombophilia in a cohort of mothers and infants presenting with perinatal arterial ischemic stroke. METHODS: Forty-seven infants with clinically and radiologically confirmed perinatal arterial ischemic stroke underwent thrombophilia workup: factor V Leiden (FVL), PII20210A mutation, Methylene-tetrahydrofolate reductase 677T polymorphism, protein C, protein S, antithrombin, FVIII, and antiphospholipid antibodies. Thrombophilia data were available for 23 mother-infant pairs and compared with control populations to evaluate the risk for PAS. RESULTS: Thirty of 47 (64%) infants and 15 of 22 mothers (68%) had evidence of thrombophilia. In 18 of 23 (78%) mother-infant pairs, there was at least 1 thrombophilic risk factor, but 15 pairs were mismatched in pathology. Among infants, FVL, protein C deficiency, and presence of antiphospholipid antibodies prevailed (OR, 4.2; 95% CI, 1.5-11.3; OR, 12.2; 95% CI, 2.5-59.9; OR, 4.1; 95% CI, 1.4-12.2, respectively). Interestingly FVL prevailed in almost one-third of mothers (OR, 8.5; 95% CI, 4.1-17.5) and 18% of mothers had antiphospholipid antibodies (OR, 3.8l; 95% CI, 1.5-10.0). CONCLUSIONS: Maternal and neonatal thrombophilia, especially presence of FVL or antiphospholipid antibodies, may be important in the pathogenesis of perinatal arterial ischemic stroke. The nature of thrombophilic mother-infant risk potential interactions warrants further investigation.

Efficacy and safety of a prothrombin complex concentrate (Octaplex) for rapid reversal of oral anticoagulation.

Bleeding is the most serious adverse event of oral anticoagulants and is a major cause of morbidity and mortality in such patients. Rapid reversal of anticoagulation in bleeding patients or prior to urgent surgery is mandatory. The therapeutic options in these situations include administration of fresh frozen plasma (FFP), and recently of prothrombin complex concentrates (PCCs). However, viral safety and thrombogenicity of PCCs remain issues of concern. In the present study, we administered Octaplex, a new solvent/detergent (S/D) treated and nanofiltered PCC, to excessively anticoagulated bleeding patients or to anticoagulated patients facing urgent surgery. Ten excessively anticoagulated patients with major bleeding and 10 anticoagulated patients awaiting surgery (median age 72.5 (43-83) years, 9 females) received a median dose of 26.1 IU/kg body weight (BW) of Octaplex for reversal of anticoagulation. Response to Octaplex was rapid with decline of INR within 10 min after Octaplex administration (from 6.1+/-2. to 1.5+/-0.3). Clinical response was graded as good in most patients (85%) and as moderate in the rest. Octaplex administration was uneventful in all patients. Following Octaplex administration, a small increase in F1+2 levels was observed in bleeding patients, whereas D-dimer level did not change significantly. We conclude that Octaplex is effective and safe in situations where rapid reversal of anticoagulation is needed.

Phase I/II, open-label, multicenter, safety, efficacy and PK study of a recombinant coagulation factor IX albumin fusion protein (rIX-FP) in subjects with hemophilia B.

Recombinant fusion protein linking coagulation factor IX with albumin (rIX-FP) is a novel recombinant albumin fusion protein designed to extend the half-life of recombinant factor IX (rFIX), which is used in the management of hemophilia B. Clinical evaluation of rIX-FP in humans is underway, including a recently completed phase I/II, open-label, multicenter, study that assessed the safety, pharmacokinetics, and efficacy of rIX-FP in patients with severe hemophilia B. A total of 17 patients received rIX-FP (25 IU/kg) as either on-demand therapy (n = 4) for 20 weeks or weekly prophylaxis (n = 13) for up to 44 weeks. Preliminary results confirm that rIX-FP has an excellent safety profile and a pharmacokinetic profile highlighted by a marked extended half-life, suggesting that weekly prophylaxis with rIX-FP at a dose of 25 IU/kg may be appropriate in patients with severe hemophilia B, and that extended dosing intervals (10-14 days) may be feasible in some patients. A phase II/III study evaluating the safety and efficacy of rIX-FP in patients with hemophilia B is underway.

Risk factors for failure of heparin thromboprophylaxis in patients with acute traumatic spinal cord injury.

UNLABELLED: Venous thromboembolism (VTE) is a well-recognized complication of Acute Traumatic Spinal Cord Injury (ATSCI). Despite prophylaxis by heparins, VTE occurs in a substantial number of ATSCI patients without an obvious explanation. In this matched case-control study we examined whether thrombophilia and other risk factors are associated with failure of thromboprophylaxis. Cases and controls receiving heparin thromboprophylaxis were selected from consecutively admitted ATSCI patients. Patients who developed a new, objectively confirmed, symptomatic VTE despite prophylaxis at hospital were matched by gender, age, level and mechanism of ATSCI with 2-3 controls without VTE. Patients were interviewed about VTE risk factors and tested for factor V Leiden (FVL), prothrombin G20210A (PT), methylenetetrahydrofolate reductase C677T homozygosity (MTHFR), lupus anticoagulant, homocysteine (Hcy) and plasma factor VIII (FVIII) levels. Twenty-two patients with new VTE episodes and 64 controls were ascertained. The total number of gene alterations for MTHFR, FVL and PT or elevated levels of Hcy or FVIII was significantly more common in patients compared to controls (82% vs. 48%, p=0.006). Multiple logistic regression proved the PT mutation, a positive family history of thrombosis and elevated levels of either FVIII or Hcy to be predictors of thrombosis. CONCLUSION: A positive family history of VTE, carriership of the prothrombin mutation and elevated FVIII or Hcy levels were significantly associated with failure to prevent VTE by heparin therapy following ATSCI. Testing for thrombophilia in patients with ATSCI and possibly a more intense thromboprophylactic regimen seem desirable but need to be verified by a prospective study.

Effect of enoxaparin on homocysteine concentration in warfarin-treated patients.

BACKGROUND: Elevated plasma total homocysteine (tHcy) concentration is an emerging independent risk factor for hypercoagulability states and cardiovascular diseases. Many disease states and various drug treatment regimens are known to affect plasma tHcy concentration. OBJECTIVE: To examine the effect of short-term treatment with the low-molecular-weight heparin enoxaparin on plasma tHcy concentrations. METHODS: A prospective study was conducted in an outpatient anticoagulation clinic set in a tertiary care referral medical center. Subjects included twenty-four consecutive patients treated with warfarin who were scheduled for short-term enoxaparin treatment. Fasting plasma tHcy concentrations were measured before and after 3 days of enoxaparin treatment in patients who began short-term therapy with enoxaparin because of temporary inadequate anticoagulation (international normalized ratio <1.5). The main outcome measures were the difference in tHcy concentration between baseline and after enoxaparin treatment. RESULTS: tHcy plasma concentrations decreased in most patients (n = 21), did not change in 2, and increased in 1 patient after 3 days of enoxaparin treatment. The decline of tHcy was statistically significant: from 9.8 +/- 3.4 to 7.6 +/- 2.6 micro mol/L (mean +/- SD; p < 0.005). This decline was more prominent in patients with baseline tHcy plasma concentrations above the normal range compared with patients with normal baseline concentrations. Six patients in whom a third sample was obtained 15-30 days after the last enoxaparin injection developed decreased mean tHcy plasma concentrations: from 9.1 +/- 3.0 micro mol/L at baseline to 6.4 +/- 2.0 micro mol/L on day 3 and further to 5.7 +/- 1.8 micro mol/L on days 15-30. No relation was found between age, gender, treatment indication, and average weekly dose of warfarin to the presence or magnitude of tHcy plasma concentration decline. CONCLUSIONS: Short-term treatment with enoxaparin reduces plasma tHcy concentrations. Further studies are needed to clarify the mechanism and the clinical significance of enoxaparin's effect.