Tissue factor-induced Thrombin Generation in the Fasting and Postprandial State among Elderly Survivors of Myocardial Infarction

Introduction

Tissue factor (TF)-induced thrombin generation (TG) ex vivo has been suggested to be an important method to assess thrombotic risk. No studies have investigated the impact of postprandial lipemia on TF-induced TG. Since myocardial infarction (MI) is associated with elevated postprandial levels of triglycerides, we hypothesized a differential impact of postprandial lipemia on coagulation activation in MI-patients and healthy controls.

Material and Methods

Elderly survivors of acute MI (n = 44) and healthy age-and sex matched controls (n = 43) underwent a fat tolerance test (1 gram per kg body weight) to assess coagulation activation during postprandial lipemia.

Results

The incremental area under the curve (AUCi) for serum triglycerides was higher in MI-patients than in healthy age-and sex matched controls (5.64 ± 0.52 mmol/L?h and 3.94 ± 0.39 mmol/L?h, p = 0.012) during the postprandial phase. Subsequent endogenous activation of coagulation, assessed by FVIIa and thrombin generation (F1 + 2), was similar among groups and not related to levels of triglycerides during the postprandial phase. Healthy individuals had a gradual decline in TF-induced thrombin generation ex vivo, assessed by endogenous thrombin potential (ETP) (AUCi = - 542.4 ± 71.4 nM?min?h, p < 0.001), whereas MI-patients retained their ETP (AUCi = 127.4 ± 89.0 nM?min?h, p = 0.47) in plasma during the postprandial phase (p for group difference = 0.005).

Conclusions

MI-patients had elevated postprandial lipemia and retained their ability for TF-induced TG in plasma ex vivo in the postprandial phase, whereas the capacity gradually decreased in healthy individuals. Further studies are warranted to reveal underlying mechanism(s) and clinical implications.     

Inflammatory and thrombotic markers in patients with ST-elevation myocardial infarction treated with thrombolysis and early PCI: A NORDISTEMI substudy

Introduction

Both pharmacological and invasive treatment might influence the inflammatory and pro-thrombotic responses observed in acute ST-elevation myocardial infarction (STEMI). We aimed to study whether circulating levels of inflammatory and pro-thrombotic markers differ in STEMI patients treated with early angioplasty compared to standard therapy following thrombolysis. Furthermore, we wanted to study if levels of markers were related to infarct size.

Materials and Methods

This was a substudy of the NORwegian study on DIstrict treatment of ST-Elevation Myocardial Infarction (NORDISTEMI), in which STEMI patients treated with thrombolysis were randomized to early invasive or standard therapy. Fasting blood samples were collected in the morning 3 days and 3 months after onset of STEMI. Commercially available ELISA methods were used for determination of inflammatory and pro-thrombotic markers. Infarct size was assessed by SPECT after 3 months.

Results

246 patients were included in this substudy. At 3 days, levels of prothrombin fragment 1 + 2 and D-dimer were higher in the early invasive compared to the standard treatment group, whereas levels of soluble CD40 ligand were lower (p < 0.01 for all). No other differences between groups were found in any of the measured markers. Significant, although weak correlations were found between Day 3 levels of C-reactive protein, interleukin-6, prothrombin fragment 1 + 2 and D-dimer, and infarct size assessed by SPECT after 3 months.

Conclusions

An early invasive strategy following thrombolysis for STEMI was associated with higher subacute levels of D-dimer and prothrombin fragment 1 + 2, and lower levels of soluble CD40 ligand than standard treatment. Further studies are needed to establish the relation between these changes and clinical outcome.The NORDISTEMI was registered at www.clinicaltrials.gov, NCT00161005.     

Fibrin clot properties in women heterozygous for factor V Leiden mutation: Effects of oral contraceptives

Introduction

Oral contraceptives (OC) in the presence of factor V Leiden mutation (FVL) markedly increase the risk of venous thromboembolism (VTE). Little is known about the OC and FVL-related alterations in fibrin clot properties.

Subjects and Methods

Plasma fibrin clot permeability (K_s) and efficiency of lysis, reflected by clot lysis time (CLT) and the rate of D-dimer release from clots (D-D_rate) induced by recombinant tissue plasminogen activator (tPA) were determined in 25 women with a family history of VTE who were heterozygous for FVL [FVL(+/−) - twice, on third-generation OC and after their discontinuation. Female non-carriers of FVL, matched for demographics, using OC and after their discontinuation served as controls (n = 25). All participants had no personal history of VTE.

Results

OC discontinuation in FVL(+/−) women resulted in shortened CLT (− 9%), and increased K_s (+ 4%) and D-D_rate (+ 1.4%; all p < 0.01). Alterations in fibrin clot properties were associated with decreased prothrombin fragments 1 + 2 (F1 + 2) (− 8%), plasminogen activator inhibitor-1 (PAI-1) antigen (− 11%), and thrombin activatable fibrinolysis inhibitor (TAFI) activity (− 20%; all p < 0.01). During OC use FVL(+/−) carriers compared with non-carriers had higher platelet count, activity of PAI-1, TAFI, and tPA, as well as prolonged CLT and higher D-D_max, along with lower D-D_rate and K_s. Multiple regression analysis adjusted for fibrinogen and age, showed that PAI-1 antigen and TAFI activity independently predicted CLT in FVL(+/−) women on OC.

Conclusion

FVL(+/−) is associated with hypofibrinolysis in apparently healthy women and third-generation OC administration unfavorably alters plasma clot characteristics in female FVL(+/−) carriers with a family history of thrombotic events.     

Comparison of a direct Factor Xa inhibitor, edoxaban, with dalteparin and ximelagatran: A randomised controlled trial in healthy elderly adults

Introduction

Edoxaban (the free base of DU-176b) is a new, oral direct Factor Xa inhibitor. This is the first study to compare the hemostatic response to edoxaban, ximelagatran, and dalteparin in healthy, elderly adults.

Materials and Methods

In this open-label, active-controlled clinical trial, 40 adults (65-75 years), were randomised to: oral edoxaban (60 mg, twice-daily, 7 doses), subcutaneous dalteparin (5000 IU, once-daily, 4 doses), oral ximelagatran (24 mg, twice-daily, 7 doses) or no drug. Blood samples were taken before, and 1.5, 4, 12, 24, 72, 84, 96, 108, 120, and 144 hours after, the first dose. The primary outcomes were changes in thrombin-antithrombin complex, prothrombin fragment 1 + 2 and D-dimer, and adverse events. Additional biomarkers of coagulation, and endothelial cell and platelet activation were compared (ANOVA).

Results

All subjects completed the study. Inhibition of thrombin generation lag time, peak, and constant velocity index were significantly greater, and extended for a longer period of time, following edoxaban administration, compared with dalteparin. We found that the traditional assay for anti-FXa activity was not appropriate for the new anticoagulants. Biomarker changes following edoxaban administration (including prolongation of prothrombin time) reflected inhibition of Factor Xa; there was no effect on platelet, tissue factor or endothelial activation. There were no clinically significant changes in primary outcomes. No serious adverse events were reported.

Conclusion

Oral administration of edoxaban resulted in effective Factor Xa and TG inhibition, and was well-tolerated. Studies are needed to confirm edoxaban (60 mg daily) use in clinical practice.

Sponsorship

Daiichi Sankyo Pharma Development.     

oxLDL – the molecule linking hypercoagulability with the presence of cardiovascular disease in hemodialyzed uraemic patients

Introduction

Patients with end-stage renal disease (ESRD) exhibit features of a hypercoagulable state, which may contribute to cardiovascular complications. Data from “in vitro” studies suggest that cell-free plasma lipids and lipoproteins may be capable to support thrombin generation. The aim of this study has been to establish the role of plasma oxidized LDL (oxLDL) in the coagulation activation in hemodialyzed (HD) patients with and without cardiovascular disease (CVD).

Materials and Methods

We examined relationship between a marker of coagulation activation – prothrombin fragments 1 + 2 (F_1 + 2), and plasma oxLDL levels in 60 HD patients with and without CVD and in 20 healthy controls.

Results

F_1 + 2 levels were significantly higher in HD patients than in controls, and they were higher in HD patients with CVD compared to those without CVD (p < 0.001). Conversely, oxLDL levels were similar in HD patients with CVD and healthy controls, whereas this parameter was lower in HD patients without CVD when compared to controls and patients with CVD (both p < 0.01). Close positive and independent association was between F_1 + 2 and oxLDL levels in HD patients. Nitrates treatment and the presence of pyelonephritis were associated with reduced oxLDL as well as hypercoagulability in HD patients with cardiovascular complications.

Conclusion

This study demonstrates the independent association between oxLDL and the marker of coagulation activation - F_1 + 2 in HD patients. This new observation may offer a better understanding of the complex mechanism leading to hypercoagulability, which is markedly intensified in these patients, particularly in those with CVD.     

Prospective comparison of new Japanese Association for Acute Medicine (JAAM) DIC and International Society of Thrombosis and Hemostasis (ISTH) DIC score in critically ill septic patients

Introduction

We prospectively compared the new Japanese Association for Acute Medicine (JAAM) score with the International Society of Thrombosis and Hemostasis (ISTH) score for diagnosis of disseminated intravascular coagulation (DIC) in septic patients admitted in a general critical care intensive care unit.

Material and method

Septic patients with platelet count of < 150 × 10⁹/L were included. Both DIC scores were estimated from day 1 to day 4 along with APACHE II and SOFA scores.

Results

Out of the 148 blood samples drawn from 42 patients (28 male & 14 female) the JAAM and ISTH DIC scores had an overall significant agreement (k = 0.246, p < 0.001) in 83 samples. JAAM score had higher diagnostic rates on all four days. Significant (p ≤ 0.001) day wise variation existed in JAAM and ISTH DIC scores. Correlation between JAAM DIC and ISTH DIC scores on day 1 (r = 0.631) & day 4 (r = 0.609) was significant (p < 0.001). Pneumonia was the predominant cause of sepsis. Twenty seven (64.3%) patients died during their stay in ICU. Amongst DIC patients both severity scores (SOFA/APACHE II) and DIC scores (JAAM/ISTH) did not discriminate between survivors and non-survivors. Health care associated infection (p = 0.040), high lactate levels (p = 0.020) on day 1 and high procalcitonin levels (p = 0.036) were found to have significant discriminating ability between survivors and non-survivors. Significantly shorter length of stay was observed amongst non-survivors (p = 0.002).

Conclusions

In sepsis the JAAM DIC score identified most of the patients diagnosed by the overt ISTH criteria, but failed to discriminate between survivors and non-survivors amongst DIC patients.     

Increased activation of blood coagulation in pregnant women with the Factor V Leiden mutation

Background

The risk of venous thromboembolism is enhanced in pregnant carriers of the Factor V Leiden mutation. The primary aim of the study was to compare prothrombin fragments 1 + 2, soluble fibrin and D-dimer levels in pregnant Factor V Leiden mutation carriers with those in non-carriers. Secondary aims were to evaluate whether these biomarkers could predict placenta-mediated complications or venous thromboembolism, and to study blood coagulation after caesarean section with thromboprophylaxis and after vaginal delivery without thromboprophylaxis.

Material/Methods

Prothrombin fragments 1 + 2, soluble fibrin and D-dimer levels were studied longitudinally in 476 carriers with singleton pregnancies from gestational weeks 23–25 until 8–10 weeks postpartum.

Results

Prothrombin fragments 1 + 2 and D-dimer levels gradually increased during pregnancy. D-dimer levels were higher in carriers, both during pregnancy and puerperium, compared to non-carriers. D-dimer levels above 0.5 mg/l were found in about 30% and 20% of the heterozygous carriers at 4–5 and 8–10 weeks postpartum, respectively. Soluble fibrin levels were mainly unchanged during pregnancy, with no difference between carriers and non-carriers. Biomarker levels were similar in carriers with uncomplicated and complicated pregnancies.

Conclusion

Higher D-dimer levels indicate increased blood coagulation and fibrinolysis activity in carriers. The high proportion of carriers with D-dimer levels exceeding 0.5 mg/l postpartum must be considered when assessing the probability of venous thromboembolism. Large overlaps in biomarker levels in normal and complicated pregnancies suggest that these biomarkers cannot be used as predictors. Thromboprophylaxis following caesarean section may prevent increased activation of blood coagulation.     

Pleural ELFA D-dimer assay: a surrogate marker for malignant pleural effusion

Background

Malignant pleural effusion is associated with enhanced fibrinolysis. However, no data are available concerning the precise role of pleural D-dimer assay in pleural effusion. We therefore assessed the role of pleural D-dimer assay in predicting malignant pleural effusion.

Patients and Methods

A prospective laboratory investigation was conducted in a tertiary care teaching hospital. The study included consecutive patients with pleural effusion who presented at the Pulmonary Department between November 2009 and May 2010. Blood and pleural D-dimer levels were measured by Enzyme Linked Fluorescent assay (ELFA). The results were correlated with the clinical, laboratory, and radiological findings, and with the final diagnosis of the pleural fluid.

Results

A total of 103 patients with pleural effusion were included in the study. The Pleural ELFA D-dimer results were found to be positively correlated with pleural etiology of malignancy (p = 0.0001). Pleural etiology was also correlated with pleural LDH, pleural protein, pleural PH, pleural glucose, pleural and blood CRP, but not with ADA. In a binary logistic regression, only the pleural ELFA D-dimer assay was a significant predictor of the malignant pleural effusion (odds ratio 1.007; 95% confidence interval 1.002-1.012; p = 0.007). The area under the receiver operating characteristics curve for malignancy was 0.79. A D-dimer level of 146 mg/ml had a sensitivity of 82% and a specificity of 74%.

Conclusions

We found high D-dimer levels among malignant pleural effusion. D-dimer might be useful as a simple, noninvasive, surrogate marker for malignant pleural effusion.     

Depressive symptoms, perceived social support, and prothrombotic measures in patients with venous thromboembolism

Introduction

Psychosocial factors have been associated with both a prothrombotic state and an increased risk of venous thromboembolism (VTE). We examined the relation of depressive symptoms and social support with D-dimer, an integrative measure of enhanced coagulation activity, and several additional prothrombotic measures in patients with VTE.

Methods

We studied 173 patients with a previous deep venous thrombosis and/or pulmonary embolism (mean age ± SD 45 ± 14 years, 55% men). Clinical and lab assessments took place ≥ 3 months after VTE and ≥ 1 month after discontinuation of oral anticoagulants. The patients rated depressive symptoms and social support by validated questionnaires.

Results

After adjusting for sociodemographic and medical covariates, interactions emerged between depressive symptoms and social support for D-dimer (p = 0.012) and aPTT (p = 0.002). As opposed to patients with high levels of social support, those with low levels of social support showed a direct association of depressive symptoms with D-dimer (r = 0.19, p = 0.014) and an inverse relationship with aPTT (r = -0.14, p < 0.09). Depressive symptoms were associated with levels of thrombin-antithrombin complex (r = 0.19, p = 0.016). Greater social support was associated with prolonged aPTT (r = 0.16, p = 0.046). There were no significant associations of depressive symptoms and social support with D-dimer, fibrinogen, FII:C, FV:C, FVII:C, FVIII:C, FX:C, INR, and thrombin time.

Conclusions

Depressive symptoms are associated with enhanced coagulation activity in patients with VTE, particularly so in those who perceive low levels of social support. Conversely, high levels of social support may contribute directly and through buffering the effect of depressive symptoms to attenuated clotting activity in VTE patients.     

Detection of a procoagulable state during controlled ovarian hyperstimulation for in vitro fertilization with global assays of haemostasis

Introduction

Controlled ovarian hyperstimulation during in vitro fertilization (IVF) causes profound increments in serum estradiol which may influence haemostasis and the ovarian hyperstimulation syndrome.In the present study we investigated the effect of the standard IVF-stimulation protocol on coagulation and fibrinolysis as assessed by different global haemostatic assays.

Materials and Methods

Blood samples were drawn from 31 women during the down-regulation phase when estradiol secretion is inhibited, and before egg retrieval, i.e. when estradiol levels are at supraphysiological levels, in the following called high level stimulation phase. Haemostasis was assessed during both treatment phases with 1) the calibrated automated thrombogram which measures thrombin generation, 2) overall haemostasis potential which measures fibrin formation and degradation and 3) fibrin gel permeability measurements which measures the quality of the fibrin network.

Results

Estradiol increased from < 150 pg/mL to 5889 pg/mL (range 1620-19500 pg/mL). We found both increased thrombin generation as measured by the calibrated automated thrombogram (p < 0.001) and an increase in overall haemostasis potential (p < 0.001) from time of down-regulation to high level stimulation.

Conclusions

The assays used indicated procoagulable changes in haemostasis during in vitro fertilization. Further studies should evaluate their potential in the prediction of thrombosis and hyperstimulation.     

Activation of coagulation in amniotic fluid during normal human pregnancy

Introduction

Amniotic fluid (AF) is an important medium for fetal development which exhibits high procoagulant activities; however, the role of these procoagulants during pregnancy has not been elucidated and might be associated with pregnancy complications. The current study aimed to evaluate factor X (FX) activation and its association with tissue factor (TF), tissue factor pathway inhibitor (TFPI) and coagulation activation markers in AF during normal human pregnancy.

Methods

Activation of FX and concentration of TF, free TFPI, D-dimer and prothrombin fragments (F1 + 2) were evaluated in AF samples obtained for chromosome analysis from 91 women with normal pregnancy: 65 samples were taken from patients at 16-20 weeks of gestation, 9 samples were drawn at 21-30 weeks and 17 samples−after 30 weeks of gestation.

Results

Activation of FX in AF significantly increased during normal pregnancy (from 65 ± 41 to 205 ± 80 equivalent RVV ng/mg total protein, P < 0.0001). TF and TFPI levels in AF also rose with gestational age. In contrast, the AF concentration of D-dimer and F1 + 2, markers of coagulation activation significantly decreased when expressed per mg total protein. Levels of free TFPI correlated with TF (r = 0.5, P < 0.001), and were 8-fold higher than those of TF during pregnancy.

Conclusion

High levels of TFPI might be associated with the inhibition of procoagulant activity in amniotic fluid during normal pregnancy, which may account for the rarity of clinical amniotic fluid embolism.     

Hypercoagulability in chronic kidney disease is associated with coagulation activation but not endothelial function

Introduction

Patients with chronic kidney disease exhibit features of a hypercoagulable state and have endothelial dysfunction, which may contribute to their increased cardiovascular risk. We examined the relationship between coagulation activation and vascular function in patients with chronic kidney disease.

Materials and Methods

We measured parameters of the tissue factor pathway of blood coagulation (tissue factor, factor VIIc and factor X); natural inhibitors (tissue factor pathway inhibitor, protein C, free and total protein S, antithrombin III) and markers of coagulation activation (thrombin-antithrombin complexes, prothrombin fragment 1 + 2) in 66 stage 4&5 chronic kidney disease patients and 36 healthy controls. Their relationship with markers of vascular function (flow mediated dilatation, soluble E-selectin and thrombomodulin) and a mediator of inflammation (interleukin-6) was determined.

Results

Up-regulation of the tissue factor pathway (increased tissue factor and factor VIIc), increased prothrombin fragment 1 + 2 and significant reductions in antithrombin III and the ratio of free protein S: total protein S were found in patients compared to healthy controls. Increased tissue factor antigen was significantly and independently correlated with creatinine and interleukin-6 (P < 0.001). Factor X and antithrombin III were both reduced in chronic kidney disease and correlated (r = 0.58; P < 0.001). Changes in coagulation and anti-coagulation were independent of all measures of endothelial function.

Conclusions

Significant activation of the TF pathway of coagulation and depletion or reduction of some natural anticoagulants in chronic kidney disease was correlated with the degree of renal dysfunction, but not correlated with the abnormalities of vascular function. These data are consistent with a hypercoagulable state in chronic kidney disease that may be independent of endothelial based regulation but associated with an inflammatory state.     

The relationship between aortic aneurysm sac thrombus volume on coagulation, fibrinolysis and platelet activity

Aim

Abdominal aortic aneurysm (AAA) is associated with chronic mural inflammation and a pro-thrombotic diathesis. It has been suggested that both may be related to biologically active intra-sac thrombus. The aim of this study was to examine the relationship between thrombin generation, fibrinolysis, platelet activity and AAA sac thrombus volume.

Methods

30 patients (29 men) of median (IQR) age 75 (71-82) years with an infra-renal AAA > 5.5 cm in antero-posterior diameter were prospectively studied. AAA, lumen and thrombus volumes were calculated using a CT workstation (Vitrea). Plasma thrombin-antithrombin (TAT), plasminogen activator inhibitor (PAI)-1, and soluble (s) P-selectin were measured as biomarkers of coagulation, fibrinolysis and platelet activity, respectively

Results

Median (IQR) AAA total, lumen and thrombus volumes were 188 (147-247) cm³, 80 (54.3-107) cm³ and 97.6 (63-127) cm³ respectively.TAT levels were significantly higher (median, QR, 7.15 [4.7-31.3] μg/L, p = < 0.001) and sP-selectin levels significantly lower (median, IQR, 80.5 [68-128] ng/ml, p = < 0.0001) than the normal range. PAI-1 levels (median, IQR, 20.9 [8.4-50.7] ng/ml) were normal. There was no correlation between AAA thrombus volume and PAI-1 (r = − 0.25, p = 0.47), sP-Selectin (r = 0.26, p = 0.43) or TAT plasma levels (r = − 0.21, p = 0.54).

Conclusion

The present study confirms that patients with AAA demonstrate haemostatic derangement, but the extent of the haemostatic derangement does not correlate with AAA sac thrombus volume.     

Increased thrombin generation in inflammatory bowel diseases

Background

Inflammatory bowel diseases (IBD) are characterized by an increased thrombotic risk of uncertain etiology. Endogenous thrombin potential (ETP), a parameter of the thrombin generation curve, represents a new tool in the evaluation of thrombotic and bleeding disorders.

Aims

To study ETP in IBD patients and to correlate the results with clinical and biochemical features.

Methods

Seventy-four IBD patients (37 ulcerative colitis and 37 Crohn's disease) and 74 sex- and age-matched healthy individuals. ETP was measured upon activation of coagulation with small amounts of tissue factor and phospholipids in the presence or absence of thrombomodulin; results were expressed as nM thrombin·minutes.

Results

Mean±SD ETP values were significantly higher in patients (1,499 ± 454) than controls (1,261 ± 385) (p < 0.001) only when the test was performed in the presence of thrombomodulin. ETP evaluated as ratio (with/without thrombomodulin), taken as an index of hypercoagulability, was significantly higher in patients (0.69 ± 0.14) than controls (0.62 ± 0.18) (p < 0.006). Patients with increased C-reactive protein (CRP) had significantly higher mean ETP (1,721 ± 458) than those with normal CRP (1,357 ± 394) or controls (1,261 ± 385) (p < 0.001). Patients who at the time of blood sampling were classified as having a clinically active disease had ETP higher than those who were quiescent (1,655 ± 451 versus 1,388 ± 427, p < 0.001) or controls (1,261 ± 385, p < 0.001).

Conclusions

ETP measured in the presence of thrombomodulin or as ratio (with/without thrombomodulin) is increased in IBD patients, mainly in those with increased CRP or active disease. It may be considered as a candidate test for prospective studies aimed at assessing the risk of thrombosis in IBD patients.     

Plasma fibrin clot properties in arterial hypertension and their modification by antihypertensive medication

Background

We sought to determine plasma fibrin clot properties in hypertensive subjects and to evaluate potential effects of antihypertensive therapy on these parameters.

Patients and Methods

Sixty-one patients (30 men, 31 women) with essential arterial hypertension stage 1 or 2 (aged 46.6 ± 14.4 years), free of clinically evident vascular disease, were randomly allocated for monotherapy with one of the 5 antihypertensive agents, i.e. quinapril, losartan, amlodipine, hydrochlorothiazide, or bisoprolol. Plasma fibrin clot permeability, turbidimetry and efficiency of fibrinolysis were investigated at baseline and after 6 months of therapy.

Results

Baseline systolic blood pressure in a 24-hour ambulatory monitoring was correlated with clot permeability (r = − 0.37, p < 0.05), lysis time (r = 0.42, p < 0.05) and maximal D-dimer concentration released from clots (r = 0.45, p < 0.05). Antihypertensive treatment resulted in reduction of systolic/diastolic blood pressure in office measurements and 24-hour monitoring (all p < 0.001), accompanied by an increase in clot permeability, reduction in clot lysis time and lower maximal D-dimer concentration released from fibrin clots (all p < 0.05). No changes were observed in turbidimetric variables. Posttreatment changes in plasma fibrin clot properties were related to reductions in systolic blood pressure, complement component C3 and total cholesterol.

Conclusions

Reduction in systolic blood pressure during antihypertensive treatment leads to increased plasma fibrin clot permeation and susceptibility to lysis, which might be a novel antithrombotic mechanism of blood pressure lowering therapy.     

Stent implantation in the superficial femoral artery: Short thrombelastometry-derived coagulation times identify patients with late in-stent restenosis

Introduction

The mechanisms of restenosis, the recurrence of luminal narrowing, are complex and incompletely understood to date. Thrombin, the pivotal enzyme in haemostasis, presumably contributes to the formation of in-stent restenosis (ISR). It was therefore the aim of our study to investigate whether blood coagulation/thrombin generation plays a critical role in the formation of ISR in peripheral artery disease patients with stent angioplasty in the superficial femoral artery.

Materials and Methods

We aimed to examine in this retrospective study whether patients with high-degree restenosis (50-75% lumen diameter reduction, n = 20) are in a hypercoaguable state implying enhanced readiness to generate thrombin compared to patients with low-degree restenosis (< 50% lumen diameter reduction, n = 14).

Results

The coagulation tests calibrated automated thrombography, activated partial thromboplastin time, platelet aggregation, platelet adhesion, fibrinogen, and microparticles’ procoagulant activity did not indicate a different coagulation status in the two patient groups. However, the thrombelastometry-derived value Coagulation Time (CT) was significantly shorter in the high-degree restenosis group (p = 0.012), indicating a hypercoagulable state of patients with high-degree restenosis. Under our experimental conditions, CTs shorter than 444.5 s identify patients at high risk (sensitivity = 95%) for luminal narrowing.

Conclusions

Our study supports the assumption that blood coagulation/thrombin generation plays a critical role in the development of ISR in peripheral arteries after stent insertion and that the thrombelastometry-derived CT might be a suitable value to identify peripheral artery disease patients at risk for development of high-degree in-stent restenosis in the superficial femoral artery.     

Inhibition of factor XI reduces thrombus formation in rabbit jugular vein under endothelial denudation and/or blood stasis

Introduction

In addition to acquired and inherited risk factors, the growth of venous thrombus under static conditions and endothelial injury play important roles in the development of deep venous thrombosis (DVT), for which risk factors include increased plasma levels of coagulation factor XI (FXI). The aim of this study is to understand the role of FXI in venous thrombus formation under conditions of endothelial denudation and/or blood stasis.

Materials and methods

The contribution of FXI to venous thrombus formation was investigated in a rabbit model and a flow chamber system. Thrombi were induced in the rabbit jugular veins by (1) endothelial denudation, (2) vessel ligation (blood stasis) or (3) by combined endothelial denudation and vessel ligation. Blood samples were perfused on immobilized type III collagen at a wall shear rate of 70/s and then the surface area covered by platelets and fibrin was morphometrically evaluated. Prothrombin fragment 1 + 2 (F1 + 2) generation was also measured before and after perfusion.

Results

All thrombi induced in rabbit jugular veins were composed of platelets, fibrin and erythrocytes. Anti-FXI antibody significantly reduced ex vivo plasma thrombin generation initiated by ellagic acid but not by tissue factor, and in vivo thrombus formation under endothelial denudation and/or vessel ligation. The antibody significantly reduced surface areas covered by platelets and fibrin, as well as F1 + 2 generation at a wall shear rate of 70/s in flow chambers.

Conclusion

These results suggest that FXI contributes to venous thrombus growth under conditions of endothelial denudation and/or blood stasis, and that thrombin generation by FXI interaction promotes further platelet aggregation and fibrin formation at low shear rates.     

Disseminated intravascular coagulation (DIC) diagnosed based on the Japanese Association for Acute Medicine criteria is a dependent continuum to overt DIC in patients with sepsis

Introduction

Sepsis is the most common disease associated with disseminated intravascular coagulation (DIC). To test the hypothesis that DIC diagnosed by the Japanese Association for Acute Medicine (JAAM) DIC scoring system (JAAM DIC) constitutes a dependent continuum to overt DIC diagnosed by the International Society on Thrombosis and Haemostasis (ISTH) overt DIC scoring system (ISTH overt DIC) in patients with sepsis, we conducted a retrospective study.

Materials and Methods

The databases from two prospective, multicenter clinical investigations were analyzed. The inclusion criteria comprised patients with sepsis-related DIC, who met the JAAM DIC criteria.

Results

The present study enrolled 166 patients, of whom 67 met the ISTH overt DIC criteria. All patients with sepsis who developed to overt DIC during the study period could be identified by the JAAM DIC diagnostic criteria in the first study. While the overall 28-day mortality was 31.3%, mortality (40.3%, p = 0.0040) and the incidence of multiple organ dysfunction syndrome (70.1%, p = 0.008) of the patients with the ISTH overt DIC was approximately one and a half times that of the patients associated with only the JAAM DIC. A stepwise increase in the ISTH overt DIC scores and the incidence of the ISTH overt DIC were also observed in accordance with the increase in the JAAM DIC scores.

Conclusion

DIC diagnosed based on the JAAM DIC diagnostic criteria exists in a dependent continuum to the ISTH overt DIC in patients with sepsis, thus enabling them to receive early treatment.     

Simultaneous thrombin and plasmin generation capacities in normal and abnormal states of coagulation and fibrinolysis in children and adults

Introduction

Thrombin and plasmin are the key enzymes involved in coagulation and fibrinolysis, respectively. Plasma coagulative and fibrinolytic potentials in normal children and adults, and in representative pathologically altered hemostatic states, were evaluated via simultaneous assessment of thrombin and plasmin generation.

Materials and Methods

An assay of Simultaneous Thrombin and Plasmin generation (STP) was developed to measure thrombin and plasmin in plasma using individual fluorometric substrates. Coagulation is initiated with dilute tissue factor, phospholipid, and calcium in platelet-poor plasma; fibrinolysis is accelerated via tissue plasminogen activator (tPA). Abnormal states of hemostasis were investigated.

Results

STP assay reproducibility and normal adult and pediatric values for measured and calculated parameters have been established. Onset of both thrombin and plasmin generation was significantly delayed in children relative to adults (p < 0.001) and the maximum amplitudes of thrombin and plasmin generation were less in children than adults (p < 0.01). No significant differences were measured among pediatric age groups. The most profound impairments in thrombin generation were observed for extrinsic and common pathway factor deficiencies, with the exception of afibrinogenemia. Plasmin generation was severely impaired in deficiencies of fibrinogen and plasminogen as well as with decreased tPA reagent concentration and addition of aminocaproic acid. Plasmin generation was greatly enhanced by alpha-2-antiplasmin deficiency and excess tPA reagent.

Conclusion

Simultaneous assessment of thrombin and plasmin generation in plasma shows promise for affording an enhanced understanding of overall coagulative and fibrinolytic functions in physiological and pathologically altered states of hemostasis in children and adults.     

Is fibrin formation and thrombin generation increased during and after an acute coronary syndrome?

Introduction and methods

In order to study coagulation and fibrinolysis in acute coronary syndrome (ACS) we used a recently developed assay, called OH-index, which provides simultaneous measurements of fibrin formation and fibrinolysis (fibrin degradation) in the patients´ plasma. We also investigated thrombin generation using the calibrated automated thrombogram (CAT), and assessed thrombin generation in vivo by measuring F1 + 2 plasma concentrations. In addition, to better characterize the patients we also assessed markers of inflammation and endothelial function. Eighty-seven ACS patients were sampled at admission, within 24 hours during treatment with low molecular weight heparin (LMH), and 6 months later; 65 healthy controls were also sampled.

Results

As assessed by OH-index fibrin formation was slightly depressed at admission, profoundly depressed during LMH treatment and comparable to controls at 6 months, whereas fibrin degradation was elevated, particularly during LMH treatment. F1 + 2 levels decreased during LMH treatment but did not deviate significantly from controls at admission or in convalescence. CAT data showed that peak thrombin was higher at admission and after 6 months compared to controls, whereas the endogenous thrombin potential only tended to be elevated. Both variables were strongly reduced during LMH treatment. Patients had elevated levels of markers of inflammation and endothelial function as expected.

Conclusion

ACS-patients have an increased capacity to generate thrombin and an enhanced capacity to degrade fibrin in the acute phase. Increased thrombin generation persists also 6 months after the event.