Clinical characteristics of patients with factor V Leiden or prothrombin G20210A and a first episode of venous thromboembolism. Findings from the RIETE Registry

Background

The clinical characteristics of patients with factor V Leiden or prothrombin G20210A presenting with a first episode of venous thromboembolism (VTE) have not been thoroughly studied.

Methods

RIETE is an ongoing registry of consecutive patients with acute VTE. We compared the clinical characteristics of patients with factor V Leiden, prothrombin G20210A, or no thrombophilia, at presentation with a first episode of VTE.

Results

As of May 2009, 22428 patients had been enrolled with a first episode of VTE. Of these, 345 had factor V Leiden, 261 had prothrombin G20210A, and 2399 tested negative. Sixty-two percent of the VTE episodes in women with factor V Leiden or prothrombin G20210A (40% in men) were associated with an acquired risk factor. Among women, pregnancy or contraceptive use accounted for 63% and 67% of such risk factors. Patients with factor V Leiden presented with pulmonary embolism (PE) less likely than those with prothrombin G20210A (31% vs. 51%; p < 0.001) or with negative testing (31% vs. 45%, p < 0.001). In addition, PE patients with Factor V Leiden presented with hypoxaemia (Sat O₂ levels < 90%) less likely than those with prothrombin G20210A (4.5% vs. 17%; p < 0.001) or with no thrombophilia (4.5% vs. 20%; p < 0.001).

Conclusions

Most VTE episodes in women (not men) with factor V Leiden or prothrombin G20210A were associated with an acquired risk factor (mostly pregnancy or contraceptive use). Only 4.5% of patients with factor V Leiden presenting with acute PE had hypoxaemia.     

Circulating microparticles are elevated in carriers of Factor V Leiden

Introduction

Microparticles (MP) are small membrane bound cellular particles that play an important role in thrombosis. This study was carried out to evaluate if increased numbers or procoagulant potential of circulating MP contribute to the heterogeneity in occurrence of thrombosis in heterozygotes carrying Factor V Leiden (FVL) mutation.

Methods

Levels of circulating platelet (CD41a), endothelial (CD62e) as well as leukocyte (CD45) derived MP from 45 FVL heterozygous individuals were enumerated by flow cytometry and compared with normal controls. Functional studies included enzyme linked immunoassay based prothrombinase activity (ELISA) and modified dilute Russell Viper venom test (DRVVT).

Results

Circulating MP were significantly higher in the FVL cohort compared to the controls (median = 2100 vs. 1508 MP/μl, respectively p = 0.0021).All subsets of MP (platelet, endothelial and leukocyte) were significantly elevated in the FVL group, the most striking disparity seen in the number of CD45 positive leukocyte MP. Despite the differences in the number of MP between the controls and FVL cohorts, there was no significant difference in the prothrombinase activity recorded by the ELISA (2.0 vs 2.4 PS equivalents; p = 0.7374) or clotting time assessed by the DRVVT (47 vs 46 sec, p = 0.8118). When the FVL cohort was considered alone there was no significant difference in MP parameters between FVL subjects with or without a history of thrombosis.

Conclusions

This is the first study on circulating MP levels in subjects who are heterozygote for factor V Leiden. We report that circulating platelet and leukocyte MP are elevated in carriers of this mutation and may be important contributors to risk of thrombosis.     

Gene polymorphisms and risk of adult early-onset ischemic stroke: A meta-analysis

Introduction

Genetic studies restricted to young adult ischemic stroke patients may help in excluding the potentially confounding variables encountered with advanced age; thus, allowing a more precise risk evaluation derived from the inherited mutations alone. Through meta-analysis, this study was conducted to determine the genetic risk contributed by each susceptibility gene polymorphism, particularly in adult early-onset ischemic stroke patients.

Materials and Methods

Electronic databases were searched for all the case-control studies relating to any candidate genes for ischemic stroke. The range of age was 18-50 years for cases. Fixed or random effects model was used depending on the heterogeneity between studies.

Results

Twenty-six studies were finally included in this meta-analysis; these studies focused on 7 candidate genes. A significant but modest association was identified for 2 polymorphisms, namely, methylenetetrahydrofolate reductase (MTHFR) C677T (OR = 1.44, 95% CI = 1.14-1.80) and apolipoprotein E (ApoE) ε2-4 (OR = 2.53, 95% CI = 1.71-3.73). Although the pooled analysis for platelet glycoprotein Ia (GPIa) C807T showed a positive association (OR = 1.50, 95% CI = 1.10-2.05), the Egger's test indicated the existence of publication bias (t = 5.27, P > |t| = 0.034).

Conclusions

Genetic abnormalities specific to homocysteine and lipid metabolism increase the risk for ischemic stroke at an early age. These data may offer important implications for future genetic association studies for stroke.     

Prophylactic therapy with enoxaparin in children with acute lymphoblastic leukemia and inherited thrombophilia during L-asparaginase treatment

Introduction

Thrombotic events (TE) are well documented in patients with acute lymphoblastic leukemia (ALL). They occur due to a combination of disease, host and treatment-related risk factors. Low molecular weight heparin (LMWH) has been found to be effective and safe in children with ALL during L-asparaginase treatment. At present, whether or not to give primary anticoagulant prophylaxis for TE during induction or reinduction courses to children with ALL is controversial. Our group investigated the use of LMWH as a prophylactic treatment for ALL children with a genetic prothrombotic predisposition.

Methods

Eighty consecutive children with ALL treated between the years 1999 and 2008 were studied. Genetic analysis of factor V Leiden (G1691A) and prothrombin (G20210A) gene mutations were done at diagnosis. LMWH was given once daily subcutaneously at a dose of 1 mg/kg, starting with the first dose of L-asparaginase (day 12 of induction, day 8 of consolidation) until one week after the last dose (day 40 of induction, day 25 of consolidation), to patients with inherited thrombophilia stemming from either factor V Leiden or prothrombin gene mutation.

Results

Eighteen patients were found to have a genetic predisposition for TE, all of them received prophylactic LMWH. Six of the 80 (7.5%) patients developed thromboembolic events. Three of these six had a prothrombin (PT) gene mutation and received prophylactic LMWH. No TE event occurred in patients with factor V Leiden mutation receiving prophylactic LMWH.

Conclusion

It is suggested that patients with ALL and PT gene mutation may have a higher risk of clotting complications in comparison to patients with factor V Leiden mutation. A randomized trial of LMWH should be performed to assess its safety and efficacy in preventing venous TE.     

Risk of thrombosis and infections of central venous catheters and totally implanted access ports in patients treated for cancer

Introduction

Thrombosis and infections are well known complications of central venous catheters and totally implanted access ports. These complications lead to increased costs due to prolonged hospitalisation, increased antibiotics use and need for replacement.The objectives of the study were to document the occurrence of catheter related thrombosis and infections in patients with central venous catheters and totally implanted chest ports in cancer patients and to investigate whether factor V Leiden is a risk factor for catheter related thrombosis.

Materials and methods

Between February 2002 and November 2004, 43 patients with central venous catheter or totally implanted access port were followed up to document the occurrence of catheter related thrombosis and infections. Patients received chemotherapy either for haematological malignancy or for solid tumours. Factor V Leiden (R506Q) was determined by restriction fragment length polymorphism analysis. Follow-up period ended in April 2007.

Results

Catheter related thrombosis occurred in 4 patients (4/43; 9.3%) with a totally implanted access port. None of the 3 patients with factor V Leiden had catheter related infection or thrombosis. Catheter related infections occurred in 15 patients: 10 patients (23.3%; 10/43) with central venous catheter and 5 patients (11.6%; 5/43) with totally implanted access ports. Time to infection was 32.5 days in the central venous catheter group compared to 88 days in the totally implanted access port group.

Conclusion

A higher incidence of catheter related infections was observed in patients with central venous catheters in contrast to patients with totally implanted access ports were venous thrombosis was more frequent.     

Sex-specific risk factors for recurrent venous thromboembolism

Background

Men have higher risk of recurrent venous thromboembolism (VTE) than women but this sex difference remains unexplained. In addition, whether men and women share same risk factors for recurrent VTE is unclear.

Methods

In a prospective cohort study, 583 patients (234 men and 349 women) aged 18 to 90, with a first idiopathic VTE, were followed for an average of 28 months. We assessed the association between baseline characteristics and VTE recurrence by gender.

Results

Recurrent VTE occurred in 38 women and 36 men (incidence = 4.6% and 7.5% per year respectively; HR = 1.6; 95% CI, 1.0-2.6). This relation between sex and recurrent VTE was more pronounced in patients younger than 50 years and in the presence of factor V Leiden (FVL) mutation. Multivariate analyses showed that obesity (HR, 2.8 (95% CI, 1.3-6.0)) and aging (HR, 1.3 (95% CI, 1.1-1.4) per 10 years increase) were related to an increased risk of recurrent VTE in women while FVL mutation (HR, 3.5 (95% CI, 1.5-8.1)) was a risk factor of recurrent VTE among men.

Conclusion

Men and women do not share the same risk factors for recurrent VTE. Consequently, gender has to be taken into account to improve the risk stratification and prevention of VTE recurrence.     

Variable plasma levels of Factor V Leiden correlate with circulating platelet microparticles in carriers of Factor V Leiden

Introduction

Inheritance of Factor V Leiden (FVL) is associated with an increased but variable level of risk for thrombosis. We have previously shown that FVL heterozygotes have elevated levels of circulating pro-coagulant microparticles (MP). Here we sought to determine if these subjects differed in their plasma levels of FVL and if this was related to MP concentrations and/or history of thrombosis.

Materials and Methods

The Hemoclot Quanti. V-L clotting assay was used to specifically measure FVL in plasma samples from 44 known carriers (12 M, 32 F; aged 46 ± 13 years). Circulating MP were quantified by flow cytometry using fluorochrome conjugated antibodies to platelet (CD41a), leukocyte (CD45), and endothelial (CD62e) surface markers, and MP prothrombinase activity was determined by ELISA.

Results

The cohort was found to have a mean FVL of 49.5 ± 5.6% and this was positively correlated to the total number of circulating CD41a + MP (R = 0.31, p = 0.03) but not to other MP subsets or to MP prothrombinase activity. The amount of FVL relative to normal factor V (FVL/FV clotting ratio) was calculated and found to be highly variable, ranging from 0.37 to 0.69, and significantly correlated with a history of thrombosis (n = 14; p = 0.04).

Conclusions

This is the first study to investigate the relationship between varying levels of FVL and plasma derived MP. These results are consistent with our previous findings of an increase in MP levels in carriers of FVL as compared to controls, and suggest a role for FVL/FV ratio in predicting risk of thrombosis in carriers of FVL.     

May-Thurner syndrome will be completed?

Background

The May-Thurner syndrome is a deep venous thrombosis of the left iliofemoral vein due to a compression by the right primitive iliac artery. Some authors suggested that this syndrome could be associated with genetics factors predisposing to thrombophilia.

Objectives

The aim of this article is to assess if the May-Thurner syndrome could be associated with inherited thombophilia particularly the factor V mutation.

Patients/methods

We exposed three cases of May-Thurner syndrome, all were positive for the presence of factor V Leiden.

Conclusion

Some olds syndromes can be revisited and explained by molecular research. In this case, the May-Thurner syndrome could be associated with inherited thrombophilia. This finding could explain the pathology but also open new treatments or guidelines for the management this kind of pathology.     

Compliance of antithrombotic management at a tertiary paediatric hospital with international guidelines: a 100-Day audit

Background

Increased levels of factor VIII occur as a response to vascular injury and/or inflammation, and may increase thrombotic risks. In contrast, factor VIII deficiency poses a major hemostatic challenge. The role of factor VIII in modulating hemostasis/thrombosis was investigated in plasma models of hypocoagulable and hypercoagulable state using thrombin generation (TG) assay.

Methods

TG was performed in undiluted/diluted control, FVIII-deficient, FVIII-deficient with low antithrombin (AT activity, ~ 59%), and factor XI-deficient plasma samples using relipidated tissue factor (TF, 2 pM) or dilute Actin as activators. The impact of elevated FVIII on TG was simulated by adding Humate-P (0 to 3 U/ml) to the above plasma samples. In fondaparinux (1 μg/ml) treated plasma with normal or lower AT activity effects of Humate-P vs. 60 nM of recombinant activated factor VII (rFVIIa) were also evaluated.

Results

Humate-P increased TG concentration dependently in undiluted and diluted control plasma with TF activation. With Actin activation, only the concentration dependent shortening of lag time, but no change in peak thrombin was observed. In FVIII-deficient, FVIII-deficient with low AT, and FXI-deficient samples, 3 U/ml of Humate-P increased TG, and decreased its onset with either activator. The reduced peak thrombin due to fondaparinux was reversed with Humate-P (3 U/ml) more than with rFVIIa. Elevated FVIII levels seem to favor intrinsic tenase formation and antagonize fondaparinux because anti-FIXa aptamer added to fondaparinux effectively attenuated TG.

Conclusion

Elevated FVIII supports the propagation of TG via intrinsic tenase formation under low TF condition, factor XI deficiency or in the presence of fondaparinux.     

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.     

Predictors of compulsory admission in schizophrenia-spectrum patients: excitement, insight, emotion perception

Purpose

We explored socio-demographic and clinical variables associated with compulsory admissions (CA) compared with voluntary admissions in schizophrenia-spectrum patients; moreover, we investigated the ability of excitement, emotion perception, and lack of insight to predict CA.

Methods

119 consecutive schizophrenia-spectrum patients admitted to the Servizio Psichiatrico di Diagnosi e Cura (SPDC = PES = psychiatric emergency service) of the Department of Neuroscience and Mental Health-San Giovanni Battista Hospital of Turin in the period between December 2007 and December 2009 were enrolled in the study. A backward stepwise logistic regression was used to test factors contributing to CA.

Results

CA rate in our sample was 28.5%. Previous CAs, drop-out, severity of illness, positive symptoms, excitement, emotion perception, and insight were significantly different in CA patients compared to voluntary ones. After backward selection of variables, three variables predicted CA in our sample: excitement, impaired emotion perception and lesser insight. Finally, the effect of excitement on CA status seemed partially mediated by emotion perception, the prediction model accounting for 53.8% of the variance of CA status. Conversely, insight seemed not to be a mediator of excitement on CA.

Implications

Understanding CA patterns in special populations represents a first step towards improving clinical decision-making and developing appropriate interventions and service-provision.     

Influence of smoking during pregnancy on haemostasis in healthy full term neonates

Background

Clinical and experimental researches have linked smoking to disturbances of coagulation and fibrinolysis. Several potential mechanisms are incriminated involving inflammation, fibrinogen synthesis and clotting factors. Based on the fact that the majority of tobacco components cross the placental barrier, the objective of our current study is to investigate the influence of smoking during pregnancy on neonatal haemostasis.

Study design

The study was based on a comparative evaluation of coagulation and fibronolysis between healthy full term infants of women who smoked during pregnancy and a control group. Subjects consisted of 39 newborns of smoking and 43 newborns of nonsmoking mothers. Blood samples were obtained shortly after birth and before the administration of vitamin K. Investigation included: PT, INR, aPTT, fibrinogen, coagulation factors II, V, VII, VIII, IX, X, XI, XII, vWillebrand (vWF), protein C and S, APCr, anti-thrombin (AT), t-PA and PAI-1. The independent t- test was used to compare the differences between the values of coagulation and fibrinolytic parameters at the p < 0.05 level.

Results

We discovered a statistically significant decrease in factor II and protein S levels and an elevation in t-PA and factor VIII concentrations in newborns of smoking mothers, without clinical manifestations of altered haemostasis. There were no significant differentiations in other coagulation or fibrinolytic parameters.

Conclusion

The alteration in factor II, protein S, t-PA and factor VIII in neonates exposed in utero to tobacco smoke is not accompanied by loss in the balance between coagulation and fibrinolytic pathways.     

Unexplained infertility: association with inherited thrombophilia

Introduction

Unexplained infertility represents one of the most common diagnoses in fertility care. Attention is being paid to the association between inherited thrombophilia and infertility causes. In this study we investigated the prevalence of inherited thrombophilia according to infertility causes.

Materials and methods

We studied Prothrombin gene G20210A mutation, Factor V Leiden, deficiencies in protein S and C and antithrombin in 930 Caucasian infertile women referred to Fertility Center of the Department of Sciences for Woman and Child's Health, University of Florence, of whom 230 with unexplained, 195 female and 283 male infertility, and in 240 women who have conceived naturally without hormonal stimulation therapy.

Results

A significant relationship between inherited thrombophilia [OR 95%CI 1.97 (1.05-3.68), p = 0.03] and unexplained infertility was observed, whereas no association between thrombophilia and female and male infertility was found. Significantly higher prevalence of prothrombin gene mutation in unexplained infertile women in comparison to that observed in fertile women was observed (5.7% vs 2.1% p = 0.04); the prevalence of the other thrombophilia determinants was higher, even if not significantly, in the unexplained infertile group.

Conclusions

This study demonstrates the relationship between inherited thrombophilia and unexplained infertility, thus suggesting the contribution of genetic components in modulating unexplained infertility, behind anovulation, male and tubal factor.     

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.     

Superficial venous thrombosis: prevalence of common genetic risk factors and their role on spreading to deep veins

Introduction

Superficial venous thrombosis (SVT) has been considered for a long time a limited clinical condition with a low importance, but this approach has changed in recent years, when several studies demonstrated spreading to deep veins occurring from 7.3 to 44%, with high prevalence of pulmonary embolism.

Materials and methods

To evaluate the prevalence of genetic risk factors for VTE in patients suffering from SVT on both normal and varicose vein, and to understand their role on spreading to deep veins, we studied 107 patients with SVT, without other risk factors. Ultrasound examination was performed, and the presence of FV Leiden, Prothrombin G20210A mutation, and MTHFR C677T mutation was researched.

Results

In the patients where SVT occurred in normal veins, the presence of FV Leiden was 26.3% of the non-spreading and 60% of the spreading to deep veins SVT; Prothrombin mutation was found in 7.9% of the former case and in 20% of the latter; MTHFR C677T mutation was found respectively in 23.7% and 40%. In the patients with SVT on varicose veins, the presence of these factors was less evident (6.7%, 4.4% and 6.7% respectively), but their prevalence was considerably higher (35.7%, 7.4% and 21.4% respectively) in SVT spreading to deep veins than in non-spreading.

Conclusions

Our data demonstrate the high prevalence of these mutations, especially FV Leiden and associations, in patients with SVT on normal veins and their role in the progression to deep vein system.     

Impact of P2Y12 Inhibitory Effects Induced by Clopidogrel on Platelet Procoagulant Activity in Type 2 Diabetes Mellitus Patients

Introduction

Type 2 diabetes mellitus (T2DM) patients have a variable response profile to the P2Y₁₂ receptor antagonist clopidogrel. P2Y₁₂ receptor signalling promotes platelet procoagulant activity. The aim of this study was to determine if T2DM patients with suboptimal clopidogrel response have greater platelet procoagulant activity compared with optimal responders and evaluate if this can be modulated by enhancing P2Y₁₂ receptor inhibition.

Materials and Methods

A total of 50 T2DM patients in a steady state phase of clopidogrel therapy were studied. Suboptimal responders were randomly assigned to standard (75 mg) or high (150 mg) clopidogrel maintenance therapy for one-month. Afterwards, all patients resumed standard therapy. Platelet procoagulant activity assessed by thrombin-induced platelet-fibrin clot formation using thrombelastography (TEG) was determined at baseline, one-month post-randomization, and one-month after resuming standard therapy.

Results

In the overall study population, the reaction time (R), a measure of time to initial thrombin induced platelet-fibrin clot formation, and the time to maximum rate of thrombin generation (TMRTG) values were 6.3 ± 1.7 and 7.6 ± 1.9 minutes, respectively. Suboptimal clopidogrel responders (n = 30) had acceleration of R (p = 0.002) and TMRTG (p = 0.002) compared to optimal responders (n = 20). Suboptimal clopidogrel responders treated with a 150 mg dose showed prolongation of R (p = 0.0001) and TMRTG (p < 0.0001), which returned to baseline values after resuming standard dosage. No differences were observed among patients randomized to 75 mg.

Conclusions

T2DM patients with suboptimal clopidogrel response have enhanced platelet procoagulant activity compared to patients with optimal response, which can be down-regulated by more potent platelet P2Y₁₂ inhibition using high clopidogrel maintenance dosing.     

Smoking promotes clopidogrel-mediated platelet inhibition in patients receiving dual antiplatelet therapy

Background

High on-treatment residual platelet reactivity is associated with an increased risk of adverse events after coronary stenting. Recent data suggest that cigarette smoking might enhance clopidogrel-mediated platelet inhibition. We therefore sought to investigate the influence of cigarette smoking on clopidogrel- and aspirin-mediated platelet inhibition after percutaneous intervention with stent implantation.

Patients and methods

Platelet aggregation was assessed by the VerifyNow P2Y12 and aspirin assays in 102 patients on dual antiplatelet therapy 24 hours after peripheral, coronary or carotid artery stenting. Among these, there were 33 nonsmokers, 29 former smokers and 40 current smokers. Patients in the fourth quartile of the VerifyNow assays were considered as patients with high on-treatment platelet reactivity.

Results

Current smokers had significantly lower P2Y12 Reaction Units compared with nonsmokers (p = 0.028). Former smokers also had lower adenosine diphosphate (ADP)-inducible platelet aggregation than nonsmokers, but the difference was not significant (p = 0.52). A high on-treatment residual ADP-inducible platelet aggregation was more common among nonsmokers than among current smokers (14 vs 5; p = 0.004). In a multivariate regression analysis smoking was an independent influencing variable for post-treatment ADP-inducible platelet reactivity (p = 0.026). Aspirin-mediated platelet inhibition showed no significant differences between nonsmokers and former smokers or current smokers (p > 0.3).

Conclusion

By in vitro testing, cigarette smoking is associated with enhanced clopidogrel- but not aspirin-mediated platelet inhibition. The clinical implications have to be evaluated in large prospective trials.     

Thrombomodulin-dependent effect of factor VLeiden mutation on factor XIII activation

Introduction

Factor V Leiden mutation (FV_Leiden) is associated with impaired down-regulation of activated FV procoagulant activity and loss of FV anticoagulant function that result in an increased risk of venous thromboembolism. As the downstream effects of FV_Leiden on clot formation and fibrinolyis have only partially been revealed, we investigated its effect on the activation of factor XIII (FXIII) and the cross-linking of fibrin.

Methods

In the plasma samples of fifteen healthy individuals with known FV genotypes coagulation was initiated by recombinant human tissue factor and phospholipids with or without recombinant human thrombomodulin (rhTM). FV deficient plasma supplemented with purified wild type FV or FV_Leiden were also investigated. Clots were recovered and analyzed by SDS-PAGE and quantitative densitometric evaluation of Western blots.

Results

rhTM considerably delayed the activation of FXIII in the plasma from FV wild type individuals. This effect of rhTM was significantly impaired in the plasma from FV_Leiden carriers. The results were confirmed in experiments with FV deficient plasma supplemented by FV prepared from wild type individuals or FV_Leiden homozygotes. Fibrin γ-chain dimerization was also considerably delayed by rhTM in plasma samples from individuals without Leiden mutation, but not in plasma samples from FV_Leiden heterozygotes or homozygotes. The difference between heterozygotes and homozygotes was not statistically significant.

Conclusion

The highly diminished delaying effect of TM on FXIII activation and on the cross-linking of fibrin in FV_Leiden carriers might represent a novel mechanism contributing to the increased thrombosis risk of these individuals.     

Haemostatic markers in patients with abdominal aortic aneurysm and the impact of aneurysm size

Introduction

Abdominal aortic aneurysm is a common condition with high mortality when rupturing. However, the condition is also associated with nonaneurysmal cardiovascular mortality. A possible contributing mechanism for the thrombosis related cardiovascular mortality is an imbalance between the activation of the coagulation system and the fibrinolytic system. The aim of the present study was to investigate haemostatic markers in patients with nonruptured abdominal aortic aneurysm with special regard to the influence of aneurysm size and smoking habits.

Methods

Seventy-eight patients with infrarenal aortic aneurysm and forty-one controls without aneurysm matched by age, gender and smoking habits were studied. Thrombin-antithrombin (TAT), prothrombin fragment 1 + 2 (F 1 + 2) - markers of thrombin generation, and von Willebrand factor antigen (vWFag) - considered as a reliable marker of endothelial dysfunction - were measured. Plasma levels of tissue plasminogen activator antigen (tPAag), and plasminogen activator inhibitor type 1 (PAI-1) were measured as markers of fibrinolytic activity. D-dimer, a marker of fibrin turnover, was also measured.

Results

There were significantly higher levels of TAT and D-dimer in patients with abdominal aortic aneurysm. The highest level of TAT and D-dimer were detected in patients with large compared to small AAA.

Conclusions

The present data indicate a state of activated coagulation in patients with abdominal aortic aneurysm which is dependent by aneurysm size. The activated coagulation in AAA patients could contribute to an increased cardiovascular risk in patients also with small AAA. The possible impact of secondary prevention apart from smoking cessation has to be further evaluated and is maybe as important as finding patients at risk of rupture.     

Haemostatic profile of full-term, healthy, small for gestational age neonates

Background

Small for Gestational Age (SGA) neonates often appear with haemostatic alterations, principally due to hepatic dysfunction that results from chronic intrauterine hypoxia. Polycythaemia and thrombocytopenia are common findings in this neonatal population.

Study design

We performed a comparison of coagulation, natural inhibitors and fibrinolysis between SGA and Appropriate for Gestational Age (AGA) infants born full term [gestational age (G.A.) > 37 weeks]. Study population consisted of 188 healthy newborns, 90 of whom were SGA (62 females and 28 males), while the rest were the control group (44 females and 54 males). Blood samples were obtained within 30 minutes following birth and before the administration of vitamin K. Investigation included: PT, INR, APTT, fibrinogen, coagulation factors II, V, VII, VIII, IX, X, XI, XII, vWillebrand factor, protein C and free protein S, antithrombin (AT), APCR, tPA and PAI-1. The independent t-test was used to compare the differences between the values of haemostatic parameters.

Results

Statistical analysis revealed a significant prolongation in PT, INR, elevated levels of tPA (p < 0.015, 0.01 and 0.002 respectively) and a decrease in the values of XII and free protein S (p < 0.045 and 0.007 respectively) in SGA full term neonates. The two groups had similar demographic characteristics (except birth weight), without significant differences in the values of other haemostatic parameters.

Conclusions

Despite of statistically significant differences in PT, INR, values of tPA, XII and free protein S, levels of haemostatic factors range within laboratory references for healthy full term newborns. These findings were not accompanied with clinical manifestations of altered haemostasis.