Subcutaneous Enoxaparin for Therapeutic Anticoagulation in Hemodialysis Patients

Background

Information regarding dosing of low-molecular-weight heparins (LMWH) for therapeutic anticoagulation in hemodialysis (HD) patients is limited. The aim of this study was to retrospectively compare the safety and efficacy of enoxaparin versus unfractionated heparin (UFH) for therapeutic anticoagulation in HD patients.

Materials and Methods

This retrospective chart review evaluated HD patients treated with subcutaneous enoxaparin that were matched based on the indication for anticoagulation with patients treated with intravenous UFH to achieve therapeutic anticoagulation. Primary outcome measures included 30-day incidence of thromboembolic events and major bleeding. Secondary outcomes included rehospitalization within 30 days, length of stay, and mortality.

Results

One hundred sixty-four patients were evaluated, 82 in each group. The average daily dose of enoxaparin used to target therapeutic levels was 0.7 ± 0.2 mg/kg/day (range = 0.4-1). Comparing enoxaparin to UFH, there was no significant difference in major bleeding (6.1% vs 11%, p = 0.4) or thromboembolism (0% vs 2.4%, p = 0.5). Hospital length of stay was shorter in the enoxaparin group (20 ± 53.8 vs 28.9 ± 44.5 days, p = 0.02); there was no significant difference between groups in mortality or readmission. Adjusting for risk factors for bleeding there was a slight but statistically non-significant difference between enoxaparin versus UFH (OR = 0.77, 95%CI: 0.2-3.5, p = 0.73).

Conclusions

These findings suggest that therapeutic dosing of enoxaparin, in doses that ranged from 0.4-1 mg/kg/day, was as safe as intravenous UFH in providing therapeutic anticoagulation in stable patients requiring chronic hemodialysis.     

CERTIFY: prophylaxis of venous thromboembolism in patients with severe renal insufficiency

Patients with severe renal insufficiency (sRI) have been suggested to be at an increased risk of bleeding with low-molecular-weight heparins (LMWH). We aimed at assessing the benefits and risks of certoparin in comparison to unfractionated heparin (UFH) in these patients. In this subgroup analysis of the CERTIFY trial, acutely ill, non-surgical patients ≥70 years received certoparin 3,000U aXa o.d. or UFH 5,000 IU t.i.d. One hundred eighty-nine patients had a glomerular filtration rate (GFR) ≤30 ml/min/1.73 m2, 3,050 patients served as controls. Patients with sRI had a mean age of 85.9 ± 6.6 years (controls 78.4 ± 6.0) and were treated for a mean of 9.3 ± 3.7 days (9.9 ± 4.3). Thromboembolic event rates were comparable (4.55 vs. 4.21%; OR1.08; 95%CI 0.5-2.37) but bleeding was increased in sRI (9.52 vs. 3.54%; OR2.87; 95%CI 1.70-4.83). The incidence of the combined end-point of proximal DVT, symptomatic non-fatal PE and VTE related death was 6.49% with certoparin and 2.60% with UFH (OR2.60; 95%CI 0.49-13.85). There was a decrease in total bleeding with certoparin (OR0.33; 95%CI 0.11-0.97), which was non-significant in patients with GFR >30 ml/min/1.73 m2. In two multivariable regression models certoparin and immobilisation <10 days were associated with less bleeding while a GFR ≤30 ml/min/1.73 m2 was associated with increased bleeding. A total of 11.3% of certoparin- and 18.5% of UFH-treated patients experienced serious adverse events (14.8 in patients with a GFR ≤30 vs. 5.6% vs. >30 ml/min/1.73 m2). In conclusion, certoparin 3,000U anti Xa o.d. was as efficacious as 5,000 IU UFH t.i.d. in patients with sRI but had a reduced risk of bleeding.     

Safety profile of tinzaparin versus subcutaneous unfractionated heparin in elderly patients with impaired renal function treated for acute deep vein thrombosis: the Innohep® in Renal Insufficiency Study (IRIS)

Introduction

Trials comparing the use of full dose unfractionated heparin (UFH) or low molecular weight heparins (LMWHs) in very elderly patients with impaired renal function are lacking. IRIS aimed to assess whether LMWH is at least as safe as UFH in this population.

Materials and methods

The study included renally impaired patients ≥ 70 years with acute symptomatic lower limb deep vein thrombosis (DVT). Patients were randomized to initial treatment with either tinzaparin 175 IU/kg once daily (n = 269) or activated partial thromboplastin time-adjusted UFH twice daily (n = 270). After acute management both groups received vitamin K antagonist to day 90.

Results

The trial was stopped prematurely due to a difference in mortality favoring the UFH group (11.5 vs. 6.3%; p = 0.035). Rates of clinically relevant bleedings by day 90 were similar in the tinzaparin (11.9%) and UFH (11.9%) groups, as were rates of confirmed recurrent venous thromboembolism (VTE) (2.6 vs. 1.1%; p = 0.34). As the mortality difference could not be explained by bleedings or recurrent VTE, a post-hoc analysis was performed. This identified six baseline characteristics significantly correlated with mortality, of which five were over-represented in the tinzaparin group.

Conclusion

The IRIS study was a challenging study involving patients (mean age 83 years) usually excluded from clinical studies, but its early termination has left questions unanswered. The mortality difference observed with tinzaparin vs. UFH in elderly, renally-impaired patients with DVT cannot be explained on the basis of bleedings or recurrent VTE, and may reflect an imbalance of mortality risk factors at baseline.     

Analysis of unfractionated heparin dose requirements to target therapeutic anti-Xa intensity during pregnancy

Introduction

Unfractionated heparin (UFH) does not cross the placenta and has demonstrated utility in the prevention and treatment of thrombosis during pregnancy. Limited information is available to guide initiation and monitoring of therapeutic UFH targeting an anti-Xa concentration of 0.3-0.7 u/ml during pregnancy. The objective of this study was to describe UFH doses and monitoring strategies required to achieve and maintain therapeutic anti-Xa intensity in a cohort of women treated with UFH during pregnancy.

Materials/Methods

Patients prescribed anti-Xa adjusted UFH during pregnancies occurring between January 1998 and March 2005 were included.

Results

A total of 39 pregnancies for 37 women were identified. Unfractionated heparin doses were titrated to achieve a mid-interval anti-Xa level of 0.3-0.7 u/ml. Patients required a median 6.5 days and a mean UFH dose of 403.5 u/kg/day to achieve therapeutic anti-Xa levels. Most anti-Xa levels were within the target range (59%). The final UFH dose/kg required at the end of pregnancy was similar to that at the first therapeutic level (P > 0.05); however some patients did require dose modification. Patients required a mean 14.1 anti-Xa determinations and 4.6 dose modifications during a mean 23.9 weeks of antenatal UFH therapy. Patient weight and UFH dose at the first therapeutic anti-Xa level were correlated (r = 0.383, P = 0.018).

Conclusions

Pregnant women required a mean UFH dose of 403.5 u/kg/day to achieve midinterval anti-Xa levels of 0.3-0.7 u/ml. The required dose was correlated with patient weight and most anti-Xa measurements were within the target range.     

Peri-procedural anticoagulation management of mechanical prosthetic heart valve patients

Introduction

To estimate the three-month cumulative incidence of thromboembolism and bleeding among mechanical heart valve (MHV) patients receiving peri-procedural anticoagulation management, consecutive MHV patients referred to the Mayo Clinic Thrombophilia Center for peri-procedural anticoagulation management over the seven-year period, 1997-2003, were followed for three months for thromboembolism, bleeding and vital status.

Materials and Methods

Warfarin was stopped 4-5 days prior to the procedure, and re-started after the procedure as soon as hemostasis was assured. The decision to provide bridging therapy with low molecular weight (LMWH) or unfractionated (UFH) heparin was individualized and based on the estimated risks of TE and bleeding.

Results

556 MHV patients (372 aortic only, 136 mitral only, 48 with multiple valves) underwent 580 procedures. The three-month cumulative incidence of thromboembolism was 0.9% which included: cerebral ischemia (n = 3), unstable angina (n = 1), acute myocardial infarction (n = 1). None were fatal. The cumulative incidence of major bleeding was 3.6% and fatal in 0.2%. The incidence of major bleeding events did not differ by postoperative anticoagulant strategy whether LMWH (3.7%), UFH (6.1%), or no heparin (2.4%) was used (p = 0.26).

Conclusions

The three-month cumulative incidence of thromboembolism among MHV patients in whom anticoagulation is temporarily interrupted for an invasive procedure is low. Whereas bleeding exceeds thromboembolic complications, our current practice is to restart warfarin as soon as possible post-procedure. Post-procedural heparin use is reserved for patients with the highest thromboembolic risk (mitral MHV, multiple MHVs, MHV with prior stroke or atrial fibrillation) waiting at least 48 hours before initiating.     

Incidence and characteristics of asymptomatic distal deep vein thrombosis unexpectedly found at admission in an Internal Medicine setting

Introduction

Lower limb deep vein thrombosis (DVT) is the most frequent clinical manifestation of venous thromboembolism (VTE) and can involve proximal or distal veins. Distal DVT (dDVT) is often asymptomatic and data about its incidence and prognosis are scanty, especially in high risk medical inpatients. Therefore, no consensus exists on the value of detecting and treating dDVTs. Aim of study was to evaluate incidence and characteristics of asymptomatic isolated dDVT at admission in an Internal Medicine department.

Materials and methods

Consecutive patients hospitalized for acute medical illnesses, in whom VTE was not the admission diagnosis, underwent Doppler Ultrasonography. For all patients with dDVT standard treatment with therapeutic doses of low molecular weight heparin or fondaparinux was proposed. Follow-up visits were scheduled at 1, 6 and 12 weeks.

Results

One-hundred-fifty-four patients were enrolled. In 4.5% a proximal DVT and in 16.2% an asymptomatic dDVT were found. Female sex, elevated age and renal and electrolyte abnormalities were significantly associated to dDVT (p = 0.014, p = 0.009 and p = 0.046, respectively). Only low degree of mobility (LDM) was independently associated to dDVT [OR 7.97 (95%CI 2.42-26.27), p = 0.001)]. A high mortality rate, not for VTE-related causes, was found, especially in the first week, among dDVT patients.

Conclusions

We found a high incidence of clinically silent dDVTs. LDM evaluation could be useful to select patients at high risk in whom to perform a search for dDVT.     

Fixed-dose,body weight-independent subcutaneous low molecular weight heparin Certoparin compared with adjusted-dose intravenous unfractionated heparin in patients with proximal deep venous thrombosis

Subcutaneous body weight-adjusted low molecular weight heparin (LMWH) has been proven as effective and safe as intravenous aPTT-adjusted unfractionated heparin (UFH) for the treatment of patients with acute deep venous thrombosis (DVT). In this study we evaluate the efficacy of the initial treatment of proximal DVT with a fixed-dose, body weight-independent application of the LMWH Certoparin with a six month follow-up. In a prospective, multicentre, randomized, active-controlled study 1220 patients with objectively diagnosed proximal DVT were randomly assigned to subcutaneous 8000 U anti-factor Xa of Certoparin twice daily for 10 to 14 days or intravenous aPTT-adjusted UFH for 5 to 8 days. Both regimen were followed by oral anticoagulation for 6 months. The primary end point was the rate of symptomatic and objectively confirmed thromboembolic events within 6 months. The aim of the study was to demonstrate the non-inferiority of the Certoparin regimen as compared to UFH. The per-protocol analysis revealed 22 (3.8%) thromboembolic events in the Certoparin group and 24 (4.3%) in patients assigned to UFH within 6 months, thereby proving the non-inferiority (p<0.01), confirmed by intent-to-treat analysis (p<0.001). Major bleeding occurred in 6 and 7 patients started on Certoparin or UFH during the treatment period. Thromboembolic events were equally distributed in body weight categories with < 50, 50-80 and >80 kg as followed: 0, 3.6% and 4.1% of patients for the Certoparin group and 0, 4.6% and 4.2% of patients for the UFH group. The same was true for major bleeding complications with 0, 2.9% and 1.5% for Certoparin and 0, 3.5% and 4.2% for UFH. Overall mortality was 1.9% in the Certoparin group and 2.7% in the UFH group. Fixed-dose body weight-independent subcutaneous LMWH Certoparin is at least as efficacious and safe as intravenous aPTT-adjusted UFH for the initial treatment of acute proximal DVT. This effect is maintained during a 6-months follow-up of treatment with oral anticoagulation.     

Clinical outcome in Japanese elderly patients with non-valvular atrial fibrillation taking warfarin: a single-center observational study

Background

Although a lower target prothrombin time-international normalized ratio (PT-INR) with warfarin therapy is recommended in Japan for atrial fibrillation (AF) patients ≥ 70 years of age, few studies have provided supporting data. The current study aimed to evaluate the clinical outcome in elderly Japanese patients with non-valvular AF who were taking warfarin.

Methods

We conducted a cohort study of 845 consecutive non-valvular AF patients ≥ 70 years of age who were taking warfarin (median age, 74 years; 30.5% women) with a median follow-up period of 27 months (4-69 months). Of these patients, 29.7% had a history of stoke/transient ischemic attack (TIA), and 73.1% of the patients had a CHADS₂ score ≥ 2. The occurrence of thromboembolic events, including ischemic stroke, TIA and other systemic embolisms, and major bleeding events were validated through a review of medical records.

Results

The incidence of thromboembolic and major bleeding events were 3.8 and 2.1% per year, respectively. A higher incidence of both events was observed in patients with a CHADS₂ score ≥ 3. The multivariate analysis showed that prior stroke/TIA (odds ratio 1.7, 95% CI 1.0-2.7) and diabetes (odds ratio 1.7, 95% CI 1.0-2.8) were independent risks of thromoembolic events. A HAS-BLED score ≥ 3 represented a risk for major bleeding (hazard ratio 2.8, 95% CI 1.7-4.6). A PT-INR of 1.5-2.5 indicated a low incidence of thromboembolic and major bleeding events in patients with a CHADS₂ score ≥ 2.

Conclusions

Our results demonstrate that a target PT-INR of 2.0 and a range of 1.5-2.5 may be safe for elderly Japanese patients with non-valvular AF.     

Comparison of antithrombotic and hemorrhagic effects of edoxaban,a novel factor Xa inhibitor,with unfractionated heparin,dalteparin, lepirudin and warfarin in rats

Background

Edoxaban is a novel, potent and orally active direct Factor Xa (FXa) inhibitor under development for prophylaxis and treatment of thromboembolic diseases. Properties of dose response and margin of safety of anticoagulants are the key factors for a positive risk/benefit of novel oral anticoagulants.

Objectives

To compare the dose response of antithrombotic effect and margin of safety between antithrombotic and hemorrhagic effects of edoxaban with conventional anticoagulants, unfractionated heparin (UFH), dalteparin (low molecular weight heparin), lepirudin, and warfarin in rat models of thrombosis and hemorrhage.

Methods

Rats were treated with edoxaban, UFH, dalteparin, and lepirudin by continuous intravenous (iv) infusion, or with oral warfarin for 4 days before inducing thrombosis or bleeding. Thrombosis was induced by inserting a platinum wire into the inferior vena cava for 60 minutes. Tail template bleeding time was measured after making an incision on the tail.

Results

In rats, iv infusion of edoxaban inhibited venous thrombosis in a dose-dependent manner. The other anticoagulants also exerted dose-dependent antithrombotic effects. The slopes of the dose–response curves of edoxaban were significantly shallower than the slopes of UFH, dalteparin, and warfarin. At supratherapeutic doses, edoxaban prolonged bleeding time in a rat tail bleeding model. To determine bleeding risk, the margins between antithrombotic and bleeding-time prolongation were compared. The margins of safety of edoxaban were wider than those of UFH, dalteparin, lepirudin, and warfarin.

Conclusions

These results suggest that edoxaban may be more easily controlled and has the potential for a more positive risk/benefit ratio compared to conventional anticoagulants.     

Haplotypes of TAFI gene and the risk of cerebral venous thrombosis - a case-control study

Introduction

Cerebral venous thrombosis (CVT) is an uncommon disease with some differences compared to other-site thrombosis, including a higher frequency in young people, female sex and oral contraceptive users. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a regulator of fibrinolysis, whose levels are genetically controlled and its increase is associated to thrombosis. Our objective was to investigate in a case-control study the association between CVT and TAFI single nucleotide polymorphisms (SNPs) and its haplotypes in comparison to other-site venous thrombosis and controls.

Materials and Methods

Seventy two patients with CVT were compared to 143 individuals with no history of thromboembolic events (control group) and to 128 patients with deep vein thrombosis in the limbs and/or pulmonary embolism (venous thromboembolism-VTE group). SNPs were genotyped by restriction fragment length polymorphism or allele-specific PCR for F2 20210G > A, F5 1691G > A, TAFI (-1053C > T, -438G > A, 505G > A, 1040C > T and + 1542C > G).

Results

The GTC haplotype for TAFI 505G > A/1040C > T/+ 1542C > G SNPs was associated with an increased risk of CVT compared to controls [odds ratio (OR) 2.67, 95% confidence interval (CI): 1.13 - 6.34) and VTE group (OR 2.51, 95%CI: 1.07 - 8.06). The CVT risk became even more pronounced when evaluating unprovoked or hormone-related thrombosis cases: CVT compared to controls (OR 3.24, 95%CI: 1.19 - 8.82) and VTE group (OR 4.32, 95%CI: 1.27 - 14.63).

Conclusions

Our data indicate that the GTC haplotype for TAFI 505G > A/1040C > T/+ 1542C > G SNPs increased the risk of CVT in comparison to controls and VTE cases. Further studies are required to confirm our findings.     

Lower dosage of recombinant tissue-type plasminogen activator (rt-PA) in the treatment of acute pulmonary embolism: A systematic review and meta-analysis

Background and Objective

According to US Food and Drugs Administration (FDA), 2 hour recombinant tissue plasminogen activator (rt-PA) 100 mg infusion is recommended for eligible patients with acute pulmonary embolism (PE). However,there exists evidence implying that a lower dosage of rt-PA can be equally effective but potentially safer compared with rt-PA 100 mg regimen. The aim of this systematic review and meta-analysis is to assess the efficacy and safety of low dose rt-PA in the treatment of acute PE.

Material and Method

We searched Pubmed, EMBASE, the Cochrane library and CBM Literature Database for randomized controlled trials (RCT) focusing on low dose rt-PA for acute PE. Outcomes were described in terms of changes of image tests and echocardiography, major bleeding events, all-cause death, and recurrence of PE.

Results

Five studies (440 patients) were included, three of which compared low dose rt-PA (0.6 mg/kg, maximum 50 mg or 50 mg infusion 2 h) with standard dose (100 mg infusion 2 h). There were more major bleeding events in standard dose rt-PA group than in low dose group (OR 0.33, 95%CI 0.12-0.91;P = 0.94,I² = 0%), while there were no statistical differences in recurrent PE or all cause mortality between these two groups. Two studies compared low dose (0.6 mg/kg, maximum 50 mg/2 min bolus or 10 mg bolus, ≤ 40 mg/2 h) with heparin. There was no significant difference in major bleeding events (OR 0.73, 95% CI 0.14-3.98;P = 0.72), recurrent PE or all cause mortality. No dose-related heterogeneity was found for all the included studies.

Conclusions

The results of this meta-analysis were hypothesis-generating. Based on the limited data, our systematic review suggested that low dose rt-PA had similar efficacy but was safer than standard dose of rt-PA. In addition, compared with heparin, low dose rt-PA didn’t increase the risk of major bleeding for eligible PE patients.     

Dabigatran, rivaroxaban and apixaban versus enoxaparin for thomboprophylaxis after total knee or hip arthroplasty: pool-analysis of phase III randomized clinical trials

Objectives

To compare the main efficacy and safety endpoints of the pivotal randomised clinical trials (RCTs) on venous thromboembolism (VTE) prevention after total hip (THR) or knee (TKR) replacement with the new oral anticoagulants (NAs) versus enoxaparin.

Methods

A pool-analysis of 10 RCTs that included 32.144 randomised patients was performed. Efficacy outcomes were total VTE and all-cause mortality, major VTE, and proximal DVT. Safety outcomes were major bleeding, and clinically relevant (major or non-major) bleeding.

Results

Overall, a significant effect favouring NAs was found for the primary efficacy outcome (RR 0.71; 95%CI 0.56-0.90), major VTE (RR 0.59; 95%CI 0.41-0.84), and proximal DVT (RR 0.51; 95%CI 0.35-0.76). Compared to enoxaparin 40 mg QD, rivaroxaban showed superiority (RR 0.50; 95%CI 0.34-0.73), followed by apixaban (RR 0.63; 95%CI 0.36-1.01) and dabigatran (RR 1.02; 95%CI 0.86-1.20). There was significant heterogeneity among trials and subgroups analysed for these efficacy outcomes. Major bleeding (RR 1.04; 95% CI 0.74-1.46) and clinically relevant bleeding (RR 1.03; 95%CI 0.88-1.21) was similar with NAs or enoxaparin. Rivaroxaban showed a trend toward more major bleeding episodes than enoxaparin (RR 1.88; 95%CI 0.92-3.82) and apixaban showed the lowest clinically relevant bleeding risk (RR 0.81; 95%CI 0.64-1.01).

Conclusions

Overall, NAs showed more efficacy and same safety when compared to the recommended dose of enoxaparin after THR and TKR. There are little differences in efficacy and bleeding risk among NAs and the type of prophylaxis that should be analysed further.     

Meta-Analysis to Assess the Quality of International Normalized Ratio Control and Associated Outcomes in Venous Thromboembolism Patients

Introduction

Patients with venous thromboembolism (VTE) frequently require vitamin K antagonists (VKAs) to prevent recurrent events, but their use increases hemorrhage risk. We performed a meta-analysis to assess the quality of international normalized ratio (INR) control, identify study-level predictors of poor control and to examine the relationship between INR control and adverse outcomes in VTE patients.

Materials and Methods

We searched bibliographic databases (1990-June 2013) for studies of VTE patients receiving adjusted-dose VKAs that reported time in range (2.0-3.0) or proportion of INRs in range and/or reported INR measurements coinciding with thromboembolic or hemorrhagic events. Meta-analysis and meta-regression analysis was performed.

Results

Upon meta-analysis, studies found 59% (95%CI: 54-64%) of INRs measured and 61% (95%CI: 59-63%) of the time patients were treated were spent outside the target range of 2.0-3.0; with a tendency for under- versus over-anticoagulation. Moreover, this poor INR control resulted in a greater chance of recurrent VTE (beta-coefficient = -0.46, p = 0.01) and major bleeding (beta-coefficient = -0.30, p = 0.02). Patients with an INR < 2.0 made up 58% (95%CI: 39-77%) of VTE cases, while those with an INR > 3.0 made up 48% (95%CI: 34-61%) of major hemorrhage cases. Upon meta-regression, being VKA-naïve (-14%, p = 0.04) and treated in the community (-7%, p < 0.001) were associated with less time in range, while being treated in Europe/United Kingdom (compared to North America) was associated with (11%, p = 0.003) greater time.

Conclusions

Strategies to improve INR control or alternative anticoagulants, including the newer oral agents, should be widely implemented in VTE patients to reduce the rate of recurrent events and bleeding.     

Relationship Between ABCB1 Polymorphisms,Thromboelastography and Risk of Bleeding Events in Clopidogrel-Treated Patients With ST-Elevation Myocardial Infarction

Introduction

This study sought to investigate the relationship of polymorphisms in ABCB1 and the predictive value of thromboelastography (TEG) on bleeding risk in clopidogrel-treated patients with ST-elevation myocardial infarction (STEMI).

Methods

467 consecutive patients with STEMI undergoing percutaneous coronary intervention (PCI) were enrolled. Twenty tag single nucleotide polymorphisms (SNPs) selected from ABCB1 gene and CYP2C19*2, *3, *17 were detected by the ligase detection reaction. Platelet reactivity was assessed by TEG. The follow-up period was 12 months.

Results

By receiver operating characteristic curve analysis, the TEG platelet mapping assay value of ADP inhibition had the best predictive value of bleeding academic research consortium definition (BARC) ≥ 3b bleedings, yielding an area under the curve (AUC) of 0.707 (95% CI 0.662-0.749, p = 0.009; cut-off value > 93.4%). ADP inhibition can also predict BARC ≥ 3 bleedings with an AUC of 0.594 (95% CI 0.546-0.640, p = 0.05; cut-off value > 92.5%). After adjustment for established risk factors of bleeding including the gain of function CYP2C19*17 allele, age, female gender, renal function, the multivariable logistic regression model demonstrated that ADP inhibition > 92.5% (OR 2.247, 95%CI 1.082-4.665, P = 0.03), carriage of rs1045642 (OR 2.943, 95%CI 1.195-7.247, P = 0.019) and rs7779562 (OR 0.453, 95%CI 0.219-0.936, P = 0.032) were independent predictors of BARC ≥ 3 bleedings. These associations were validated in a second cohort of 504 STEMI patients.

Conclusions

In STEMI patients treated with clopidogrel after PCI, the ABCB1 tag SNP rs1045642 is associated with higher risk of bleedings while rs7779562 is associated with lower bleeding risk, and ADP inhibition in TEG has a predictive value of bleedings.     

Interleukin-10 promoter microsatellite polymorphisms influence the immune response to heparin and the risk of heparin-induced thrombocytopenia

Introduction

Heparin-induced thrombocytopenia (HIT) results from an atypical immune response with synthesis of IgG antibodies (Abs) to platelet factor 4/heparin complexes (PF4/H), and probably involves both B and T cells. We investigated whether 3 single nucleotide polymorphisms (SNPs), rs1800896 (− 1082G/A), rs1800871 (− 819C/T) and rs1800872 (− 592C/A) and the polymorphic CA repeat microsatellites IL10R [5325CA(11_15)] and IL10G [8134CA(14_29)] are associated with the synthesis of Abs to PF4/heparin and HIT.

Materials and methods

Eighty-two patients with definite HIT and two control groups were studied. The first control group (Ab^neg) consisted of 85 patients without Abs to PF4/heparin after cardiopulmonary bypass (CPB). The second control group (Ab^pos) consisted of 84 patients who had developed significant levels of PF4-specific antibodies after CPB, but without HIT.

Results

Allele frequencies of the 3 SNPs were similar in HIT patients and controls. Fourteen alleles in IL10G (G16 to G29) and 3 alleles in IL10R (R13 to R15) were defined. The short G20 allele of IL10G was more frequent in Ab^neg patients (8.2%) than in Ab^pos (2.9%) and HIT patients (3%). It thereby appeared to protect against developing Abs to PF4/heparin (OR 0.29; 95% CI [0.12-0.70], p = 0.006). Combined haplotypes cH1/cH8 comprising the short G20 + R13 alleles were less frequent in HIT (OR 0.33; 95% CI [0.11-0.97], p = 0.036), and levels of Abs to PF4 in Ab^pos patients were lower in cH1/cH8 subjects (p = 0.019).

Conclusion

These results suggest that IL10 promoter microsatellite polymorphisms might influence the immune response against PF4/heparin and the risk of HIT.     

Unfractionated heparin promotes LPS-induced endothelial barrier dysfunction: a preliminary study on the roles of angiopoietin/Tie2 axis

Introduction

Heparins, including unfractionated heparin (UFH) and low-molecular-weight heparins (LMWH), are anticoagulants approved as a treatment for severe sepsis, which can also prevent apoptosis and inflammation. The aim of this study was to investigate whether UFH prevents vascular leakage induced by lipopolysaccharide (LPS) and to define the role of angiopoietin (Ang)/Tie2 signaling pathway since LPS is usually used to mimic the initiation of sepsis.

Methods

Human pulmonary microvascular endothelial cells (HPMECs) were pretreated with UFH (0.1 U/ml-10 U/ml), 15 min prior to stimulation with LPS (10 μg/ml). Those samples not receiving LPS or UFH received an equal volume of Phosphate-buffered saline (PBS). Cells were cultured under various experimental conditions for 2 h, 6 h or 12 h for analysis.

Results

1) Pretreatment with UFH significantly reduced HPMEC permeability compared with LPS-stimulated groups; 2) Pretreatment with UFH decreased the formation of stress fiber and intracellular gaps induced by LPS; 3) UFH significantly up-regulated gene expression of Tie2 and Ang-1 but down-regulated Ang-2 in HPMECs; 4) UFH prevented LPS-induced decrease in the level of ZO-1.

Conclusion

This study demonstrates that UFH enhances endothelial barrier function and Ang/Tie2 axis probably represents one of the mechanisms by which UFH exerts its protective effect.     

Thromboembolic safety and efficacy of prothrombin complex concentrates in the emergency reversal of warfarin coagulopathy

Background

There is uncertainty regarding the efficacy and incidence of thromboembolic events in patients treated with prothrombin complex concentrates (PCC) for the emergency reversal of warfarin effect.

Methods

During 2002 to 2010 we prospectively included 160 patients treated with PCC for emergency reversal of warfarin either for bleeding or because of the need of emergency surgery. A possible relationship to PCC was considered if objectively verified thromboembolism occurred within 7 days of PCC administration. Efficacy was adjudicated as good if the bleeding was controlled promptly or if the surgeon did not report excessive perioperative bleeding.

Results

We included 160 patients; 72% received PCC for bleeding. The median international normalized ratio (INR) before and after treatment with PCC was 3.5 (interquartile range [IQR] 2.6-5.4) and 1.4 (IQR 1.2-1.6). The mean dose of PCC was 1800 IU (IQR 1200-2000). In addition to PCC, 74% of the patients received vitamin K and 34% received plasma. Six patients (3.8%; 95% confidence interval [CI], 1.4-8.0%) developed thromboembolic events (3 strokes, 1 myocardial infarction, 1 deep vein thrombosis, 1 splenic infarction), possibly related to PCC. The clinical efficacy was good in 146 (91%), moderate in 6 (4%), poor in 4 (2.5%) and non-evaluable in 4 patients.

Conclusion

The administration of PCC for the emergency reversal of warfarin may be associated with a low risk of thromboembolism. The contribution of an unmasked thrombotic process by cessation of anticoagulation or of activation of coagulation by the hemorrhagic event should also be considered.     

Low level of factor V is associated with development of deep-vein thrombosis in Japanese patients

Background

Factor V, having two functions (procoagulant and anticoagulant), is a key factor in blood coagulation, and low plasma levels of factor V may be a risk factor for thrombosis.

Objective

The levels of plasma factor V antigen (FV:Ag), and the phospholipid binding capability of Factor V (FV:PL-bound) were evaluated in patients with deep-vein thrombosis (DVT).

Methods

Levels of FV:Ag, and FV:PL-bound were expressed as a percentage of the normal level found in pooled plasma from control subjects. One hundred and twenty-three Japanese patients with deep-vein thrombosis (DVT) were included, with 100 age and sex-matched healthy control subjects.

Results

The FV:Ag, and FV:PL-bound values were significantly lower in DVT patients than in healthy subjects (p < 0.05 and p < 0.005, respectively). Among the 123 patients, 30 for FV:Ag (24.4%), and 32 for FV:PL (26%) had less than the arbitrary cutoff point (set at the 5th percentile of the value for FV:Ag and FV:PL-bound from healthy subjects), and the odds ratios (ORs) were 6.1 (95% confidence interval [CI], 2.3-16.5) and 6.7 (95%CI, 2.5-17.9), respectively. When patients with a deficiency of natural anticoagulants (antithrombin, protein C, and protein S) were excluded from the analysis, the ORs increased for all patients (6.6 for FV:Ag (95%CI, 2.4-18.3) and 7.4 for FV:PL-bound (95%CI, 2.7-20.3). Moreover, twenty-one (17%) of the 123 DVT patients, and 1 (1%) of 100 control subjects had values below the cutoff points for both FV:Ag and FV:PL-bound, and the OR was 21.6 (95%CI, 2.85-163.1).

Conclusions

These results suggest that low levels of factor V are associated with development of DVT, and may be a predictor for DVT.     

ABCB1 C3435T polymorphism and risk of adverse clinical events in clopidogrel treated patients: a meta-analysis

Introduction

The ABCB1 C3435T polymorphism limits oral bioavailability of clopidogrel and may influence prognosis of patients treated with clopidogrel. Several studies have examined the association between the C3435T polymorphism and risk of adverse clinical events in clopidogrel treated patients, but the results were inconsistent. To assess the role of the C3435T polymorphism in the impact on clinical outcomes, a meta-analysis was conducted.

Methods

6 studies with 10,153 subjects were included in this meta-analysis. Fixed- or random-effects model was chosen according to heterogeneity. Publication bias was evaluated by fail-safe numbers.

Results

The association of the C3435T polymorphism with risk of overall recurrent ischemic events in clopidogrel treated patients was not statistically significant for all genetic models (OR = 1.13, 95%CI: 0.78-1.64, P = 0.51; OR = 1.15, 95%CI: 0.99-1.33, P = 0.07; OR = 1.19, 95%CI: 0.81-1.76, P = 0.37). Significant association was identified between the C3435T polymorphism and risk of short-term recurrent ischemic events (OR = 1.55, 95% CI: 1.09-2.20, P = 0.01; OR = 1.41, 95% CI: 1.06-1.87, P = 0.02; OR = 1.77, 95% CI: 1.19-2.63, P = 0.005). No statistically significant association between the C3435T polymorphism and stent thrombosis (OR = 0.79, 95% CI: 0.47-1.32, P = 0.37) or bleeding (OR = 0.98, 95% CI: 0.79-1.21, P = 0.82) was identified. The results may be affected by publication bias.

Conclusions

This meta-analysis failed to show an association between the ABCB1 C3435T polymorphism and risk of overall recurrent ischemic events, stent thrombosis or bleeding in clopidogrel treated patients. However, the association between TT homozygotes of the C3435T polymorphism and risk of short-term recurrent ischemic events may exist, but needs more studies to confirm.     

Association between the plasminogen activator inhibitor-1 4G/5G polymorphism and risk of venous thromboembolism: A meta-analysis

Introduction

The plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism was considered to be associated with risk of venous thromboembolism (VTE), while evidence remains inadequate. To provide a more accurate estimation of this relationship, we performed an updated meta-analysis of all eligible studies.

Materials and Methods

A systematical search was performed in PubMed, EMBASE, Wanfang, China National Knowledge Infrastructure (CNKI) and Cqvip databases to identify relevant studies published before March 6^th 2014. The odds ratios (ORs) with 95% confidence intervals (CIs) were pooled using the fixed/random-effects model using Review Manager 5.1 and STATA 12.0.

Results

A total of 34 studies with 3561 cases and 5693 controls were analyzed. Overall, significant association between the PAI-1 4G/5G variant and VTE risk in total population (dominant model: OR = 1.32, 95%CI: 1.13-1.54) was observed. And this variant was also related to the deep vein thrombosis risk (dominant model: OR = 1.60, 95%CI: 1.24-2.06, P = 0.0003). In the subgroup analyses on ethnicity, significant results were obtained in both Asians (dominant model: OR = 2.08, 95%CI: 1.29-3.35, P = 0.003) and Caucasians (dominant model: OR = 1.31, 95%CI: 1.10-1.56, P = 0.003). However, no significant association was found in patients with provoked VTE. In terms of subgroup analyses on co-existence of other thrombotic risk factors, the PAI-1 4G/5G polymorphism was significantly associated with VTE risk in patients with factor V Leiden mutation (dominant model: OR = 1.72, 95%CI: 1.17-2.53), but not in patients with cancer or surgery.

Conclusion

Our findings demonstrate the role of PAI-1 4G/5G polymorphism being a risk candidate locus for VTE susceptibility, especially in patients with other genetic thrombophilic disorders.