Fibrin Clot Phenotype Research Articles

Early-onset ischaemic stroke in a patient with the novel F2 c.1824C>T gene variant and PAI-1 4G/4G, MTHFR 677TT genotype

Introduction. Ischemic stroke (IS) is a heterogeneous dis-order caused by several genetic and environmental risk factors. It was suggested that coagulation disorders cause 1-4% of cases with IS, especially in patients with early onset of IS. Case report. We describe a case of a young adult male who developed an unprovoked IS. Biochemical, immunological, and thrombophilia screening, as well as DNA sequencing, were performed in order to reveal molecular pathology underlying the stroke of the patient. Thrombophilia testing showed that patient was a homozygous carrier for PAI-1 4G/5G and MTHFR C677T mutations. Additional genetic analysis revealed the presence of the recently reported F2 c.1824C>T gene variant, located in the last exon of the pro-thrombin gene and has previously been shown to cause hy-perprothrombinemia, hypofibrinolysis, and altered fibrin clot phenotype. Conclusion. Our results suggest that the newly reported F2 c.1824C>T gene variant might have a synergistic effect with PAI 4G/4G and MTHFR 677TT genotype in the formation of altered fibrin clot phenotype characterized by thin, densely packed fibrin fibers, which makes clot less susceptible to fibrinolysis and greatly in-creases the risk for early ischemic stroke onset.

Fibrinogen β chain and FXIII polymorphisms affect fibrin clot properties in acute pulmonary embolism.

Prothrombotic fibrin clot properties, including increased clot density, are in part genetically determined. We investigated whether fibrinogen alpha-chain gene (FGA) c.991A>G (rs6050), fibrinogen beta chain gene (FGB) -455G>A (rs1800790) and factor XIII gene (F13) c.103G>T (rs5985) polymorphisms affect plasma fibrin clot properties in patients with acute pulmonary embolism (PE). As many as 126 normotensive patients with PE, free of cancer, were genotyped by TaqMan assay. Fibrin clot permeability (Ks ), clot lysis time (CLT) and endogenous thrombin potential (ETP) were assessed on admission. The minor allele frequencies were as follows: FGA rs6050 (n=62, 0.31), FGB rs1800790 (n=40, 0.17) and F13 rs5985 (n=49, 0.23). There were no differences related to any of the polymorphisms with regard to demographic, clinical and laboratory data, except for fibrinogen concentration, which was higher in carriers of F13 rs5985 polymorphism (p=.024), and PE combined with deep-vein thrombosis, which was less prevalent in FGB rs1800790 polymorphism carriers (p=.004). Carriers of FGB rs1800790 A allele and F13 rs5985T allele had lower Ks , prolonged CLT and higher ETP compared with major homozygotes (all p<.05). After adjustment for fibrinogen, all differences remained significant (all p<.01). There were no associations between the FGA rs6050 polymorphism and Ks , CLT or ETP. Our study showed that FGB rs1800790 and F13 rs5985 polymorphisms contribute to the prothrombotic fibrin clot phenotype and these effects are strong enough to be observed in the acute phase of PE.

Fibrin Clot Properties in Atherosclerotic Vascular Disease: From Pathophysiology to Clinical Outcomes.

Fibrin is a major component of thrombi formed on the surface of atherosclerotic plaques. Fibrin accumulation as a consequence of local blood coagulation activation takes place inside atherosclerotic lesions and contributes to their growth. The imbalance between thrombin-mediated fibrin formation and fibrin degradation might enhance atherosclerosis in relation to inflammatory states reflected by increased fibrinogen concentrations, the key determinant of fibrin characteristics. There are large interindividual differences in fibrin clot structure and function measured in plasma-based assays and in purified fibrinogen-based systems. Several observational studies have demonstrated that subjects who tend to generate denser fibrin networks displaying impaired clot lysis are at an increased risk of developing advanced atherosclerosis and arterial thromboembolic events. Moreover, the majority of cardiovascular risk factors are also associated with unfavorably altered fibrin clot properties, with their improvement following effective therapy, in particular with aspirin, statins, and anticoagulant agents. The prothrombotic fibrin clot phenotype has been reported to have a predictive value in terms of myocardial infarction, ischemic stroke, and acute limb ischemia. This review article summarizes available data on the association of fibrin clot characteristics with atherosclerotic vascular disease and its potential practical implications.

Fibrin clot properties among women with endometriosis and the impact of ovarian stimulation

Research questionIs there a difference in fibrin clot phenotype in women with endometriosis before and after ovarian stimulation? DesignProspective study including 73 infertile women in two age-matched groups: (i) with confirmed endometriosis (n = 29); (ii) without endometriosis (n = 44). Assessments of plasma fibrin clot permeability (Ks), efficiency of fibrinolysis using clot lysis time (CLT), along with thrombin generation (prothrombin fragments 1+2 [F1+2] and endogenous thrombin potential [ETP]) and fibrinolysis inhibitors were performed together with clinical pregnancy rate. ResultsEndometriosis was associated with increased thrombin generation, reflected by both higher F1+2 (+96.1%, P = 0.005) and ETP (+14.2%, P = 0.014) along with unfavourably altered fibrin clot properties represented by lower Ks (–31%, P < 0.001) and prolonged CLT (+13.5%, P = 0.02), compared with the non-endometriosis group. Moreover, women with endometriosis had higher plasminogen activator inhibitor-1 (PAI-1; +272%, P = 0.004) concentrations and alpha-2-antiplasmin activity (+39.9%, P < 0.001) in contrast to the other group. Ovarian stimulation led to reduction in F1+2 (–48.1%, P < 0.001), improvement of fibrin clot phenotype reflected by higher Ks (+25.9%, P < 0.001) and shortened CLT (–11.9%, P < 0.001), along with lower PAI-1 (–54%, P = 0.016) compared with the baseline in women with endometriosis. ConclusionsEndometriosis is associated with the prothrombotic fibrin clot phenotype and increased thrombin generation. Ovarian stimulation favourably alters fibrin clot properties and leads to comparable pregnancy outcomes to those in women without endometriosis.

Plasma Fibrin Clot Properties as Determinants of Bleeding Time in Human Subjects: Association with Histidine-Rich Glycoprotein.

Aims Fibrin formation and histidine-rich glycoprotein (HRG) are involved in primary hemostasis and wound healing. Little is known regarding the relationship of clot characteristics, bleeding time, and wound healing. Methods and Results We studied 154 patients with coronary artery disease (CAD) and 154 subjects free of CAD matched for age, obesity, and current smoking. We evaluated bleeding time (BT) using standardized skin incisions on a forearm, along with plasma clot permeability (Ks), clot lysis time (CLT), and histidine-rich glycoprotein (HRG). Compared with controls, BT was 45% shorter in CAD cases. CAD patients had 32% lower Ks), clot lysis time (CLT), and histidine-rich glycoprotein (HRG). Compared with controls, BT was 45% shorter in CAD cases. CAD patients had 32% lower p < 0.001). After adjusting for potential confounders, Ks), clot lysis time (CLT), and histidine-rich glycoprotein (HRG). Compared with controls, BT was 45% shorter in CAD cases. CAD patients had 32% lower n = 79, 25.6%) was independently predicted by both short and prolonged BT in CAD cases (OR 21.87, 95% CI 7.41-64.55 and OR 10.17, 95% CI 2.88-35.97) and controls (OR 5.94, 95% CI 2.29-15.41 and OR 14.76, 95% CI 4.29-50.77, respectively). Conclusions The study shows that plasma fibrin clot density and HRG may influence BT and that appropriate skin wound healing is associated with medium BT. Translational Perspective. Elucidation of the complex relationships between plasma fibrin clot phenotype and wound healing might have important practical implications.

A prothrombotic state and denser clot formation in patients following acute limb ischemia of unknown cause

IntroductionFibrin clot structure differs between healthy individuals and those following thromboembolic events. Dense and poorly lysable fibrin clots have also been reported in peripheral artery disease. We studied fibrin clot properties and its determinants in individuals with a history of acute lower limb ischemia (ALI) of unknown cause. Materials and methodsIn this case-control study, we enrolled 43 patients who experienced ALI of unknown cause, and two age-and sex-matched reference groups: (1) patients with cryptogenic non-lacunar stroke (n = 43) and (2) individuals without any history of thromboembolism (n = 43, control group). Plasma fibrin clot properties, along with thrombin generation and fibrinolysis markers were assessed following ≥3 months of anticoagulation. ResultsCompared with the control group, the ALI group exhibited more compact plasma fibrin clots (13.4% lower permeability [Ks], p = .001), decreased formed clot lysis (12.5% lower D-Drate, p = .001) and unaltered clot lysis potential, along with enhanced thrombin generation potential (49% higher peak thrombin concentration, p < .0001). There were no differences in these variables between ALI and stroke patients. Patients with ALI had slightly higher α2-antiplasmin and lower plasminogen activator inhibitor 1 levels compared with the stroke and control groups (all p < .01). ConclusionsPatients who experienced ALI of unknown cause display a prothrombotic fibrin clot phenotype, including increased clot density and hypofibrinolysis associated with higher thrombin generation, which might suggest potential benefits from prolonged anticoagulation in this disease.

Plasma Fibrin Clot Properties Are Unfavorably Altered in Women following Venous Thromboembolism Associated with Combined Hormonal Contraception.

The use of hormonal contraception is associated with an increased risk of venous thromboembolism (VTE). Unfavorably altered fibrin clot phenotype has been reported in patients following unprovoked VTE who are at risk of recurrences. It remains unknown whether fibrin clot characteristics in women with contraception-related VTE differ from those in unprovoked VTE. We studied three age-matched groups of women: (1) after contraception-related VTE, (n = 48) (2) after unprovoked VTE (n = 48), and (3) controls (n = 48). Plasma fibrin clot permeability (Ks), turbidity of clot formation, efficiency of fibrinolysis using clot lysis time (CLT), and rate of increase in D-dimer during lytic clot degradation (D-Drate), along with thrombin generation and fibrinolysis proteins were determined. Compared with the controls, patients following contraception-related and unprovoked VTE formed faster (lag phase, -8.8% and -20.4%, respectively) fibrin clots of increased density (Ks, -8.6% and -13.4%, respectively) displaying impaired fibrinolysis as evidenced by prolonged CLT (+11.5% and +14.5%, respectively) and lower D-Drate (-7.1% and -5.6%, respectively), accompanied with higher plasminogen activator inhibitor-1 (PAI-1, +14.9% and +17.8%, respectively) and elevated peak thrombin generation (+63.8% and +36.7%, respectively). The only differences between women with unprovoked and contraception-related VTE were lower fibrin mass in plasma clots (D-Dmax, -8.6%), along with higher peak thrombin generation (+19.8%) and shorter lag phase (-6.8%) in the latter group. This study suggests that women after contraception-related VTE, similar to those following unprovoked VTE, have denser fibrin clot formation and impaired clot lysis. These findings might imply higher risk of VTE recurrence in women with the prothrombotic clot phenotype.

Prothrombotic clot properties can predict venous ulcers in patients following deep vein thrombosis: a cohort study

Venous ulcers are the most severe manifestation of post-thrombotic syndrome (PTS). We have previously demonstrated that formation of compact fibrin clots resistant to lysis is observed in patients following deep-vein thrombosis (DVT) who developed PTS. The current study investigated whether unfavourable fibrin clot properties can predict post-thrombotic venous ulcers. In a cohort study on 186 consecutive patients following DVT, we determined plasma fibrin clot characteristics, including clot permeability and lysability, inflammatory markers, thrombin generation, fibrinolysis proteins at 3 months since the index event. Occurrence of PTS and venous ulcers was recorded during follow-up (median, 53; range 24 to 76 months). Fifty-seven DVT patients (30.6%) developed PTS, including 12 subjects (6.45%) with a venous ulcer (4 individuals with recurrent ulcers). Patients who developed ulcers compared with the remainder had at enrolment 13.0% lower clot permeability (Ks), 17.4% longer clot lysis time (CLT), 13.1% longer lag phase of clot formation, and 5.0% higher maximum absorbance, with no difference in fibrinogen, C-reactive protein, and thrombin generation. The baseline prothrombotic fibrin clot phenotype (Ks ≤ 6.5 × 10−9 cm2 and CLT > 100 min) was associated with a higher risk of ulcers [hazard ratio (HR), 5.37; 95% confidence interval (CI), 1.3–21.5]. A multivariate model adjusted for age, sex, and fibrinogen showed that independent predictors of the ulcer occurrence were body mass index (HR 1.53; 95% CI 1.30–1.86), CLT (HR 1.43; 95% CI 1.04–2.05), and α2-antiplasmin (HR 0.95; 95% CI 0.90–0.99). This study suggests that formation of denser fibrin clots with impaired fibrinolysis predisposes to post-thrombotic venous ulcers.

Differences in plasma fibrin clot composition in patients with thrombotic antiphospholipid syndrome compared with venous thromboembolism

The prothrombotic fibrin clot phenotype has been reported in patients with thrombotic antiphospholipid syndrome (APS) and venous thromboembolism (VTE). Protein composition of plasma fibrin clots in APS has not been studied. We evaluated 23 patients with thrombotic APS, 19 with VTE alone, and 20 well-matched controls. A proteomic analysis of fibrin clots generated from citrated plasma was based on liquid chromatography-mass spectrometry. Plasma levels of thrombospondin-1 (TSP1), apolipoprotein(a), A-I, and B-100, complement components (C)3a, C5b-C9, histidine-rich glycoprotein (HRG), and prothrombin were evaluated using immunoenzymatic tests. In plasma fibrin clots of APS patients, compared with VTE subjects and controls, we identified decreased amounts of (pro)thrombin, antithrombin-III, apolipoprotein A-I, and HRG with no differences in plasma levels of antithrombin, prothrombin, along with lower plasma HRG and apolipoprotein A-I. In APS patients, plasma HRG positively correlated with amounts of clot-bound HRG, while apolipoprotein A-I was inversely associated with clot-bound levels of this protein. The most predominant proteins within the clots of APS patients were bone marrow proteoglycan, C5-C9, immunoglobulins, apolipoprotein B-100, platelet-derived proteins, and TSP1. Our study is the first to demonstrate differences in the protein composition of fibrin clots generated from plasma of thrombotic APS patients versus those with VTE alone.

Antithrombotic medications and their impact on fibrin clot structure and function.

Fibrin constitutes a major protein component of intravascular thrombi in all locations. Fibrin formation and its functions are essential for physiological hemostasis and the pathologic thrombosis. Formation of dense fibrin networks which are relatively resistant to lysis is observed in patients with venous or arterial thromboembolism, including myocardial infarction, ischemic stroke and venous thromboembolism. Measures of clot characteristics, in particular clot permeability and clot lysis time, may predict arterial and venous recurrent thromboembolic events. Medications, including vitamin K antagonists (VKA), direct oral anticoagulants (DOAC), and parenteral direct or indirect thrombin or activated factor X inhibitors increase clot permeability, reflecting fibrin network density, in association with enhanced efficiency of fibrinolysis. These effects are only in part related to decreased thrombin generation. There is evidence that aspirin can also favorably alter fibrin clot properties probably through acetylation of fibrinogen. No such effects were observed for P2Y12 inhibitors. Of note, plasma fibrin clot permeability has been shown to predict adverse clinical outcomes in patients receiving oral anticoagulants, which might have practical implications. The current review summarizes data on effects of antithrombotic agents on fibrin clot phenotype in cardiovascular disease.

Plasma fibrin clot properties affect blood loss after surgical aortic valve replacement for aortic stenosis.

Cardiac surgery is associated with elevated bleeding risk. We sought to study whether fibrin clot phenotype influences postoperative blood loss after surgery for aortic stenosis (AS). We studied 77 isolated AS patients, including 62 who underwent aortic valve replacement and 15 who underwent the Bentall procedure due to post-stenotic aortic dilation. Plasma clot properties, including the tPA-induced clot lysis time (CLT) and clot permeability (Ks), along with fibrinolysis inhibitors, a calibrated automated thrombogram and platelet activation markers, were assessed preoperatively. In the whole AS group, the median chest tube output after 12 h was 360 ml (range of 110-2290 ml). Patients with drainage in the top quartile after 12 h (≥600 ml) had lower fibrinogen, shorter CLT, higher Ks, lower plasma plasminogen activator inhibitor-1 antigen, peak thrombin generation and β-thromboglobulin levels than those in the lowest drainage quartile (≤260 ml) with no difference in platelets or von Willebrand factor. A multivariable model that was built after the exclusion of Bentall patients, adjusted for age, sex, body mass index and fibrinogen, showed that high drainage, which was defined as the top quartile after 12 h postaortic valve replacement (≥460 ml), was predicted by β-thromboglobulin [odds ratio (OR) 0.94, 95% confidence interval (CI) 0.90-0.99, P = 0.03], fibrinogen (OR 0.13, 95% CI 0.00-0.47, P = 0.02) and the CLT (OR 0.95, 95% CI 0.91-0.99, P = 0.02). The CLT was inversely related to the number of transfused platelet units (r = -0.27, P = 0.04). Fibrin clot susceptibility to lysis is a modulator of postoperative blood loss after cardiac surgery for AS, which may have practical implications.

Reduced plasma fibrin clot permeability is associated with recurrent thromboembolic events in patients with antiphospholipid syndrome.

APS is associated with arterial and venous thrombosis. The unfavourable fibrin clot phenotype, including formation of dense and poorly lysable clots, has been reported in thrombotic APS. We investigated whether abnormal plasma clot properties are predictive of recurrent thromboembolism in APS. We followed 126 consecutive patients with thrombotic APS and 105 control subjects, without APS, matched for thrombotic events. Plasma fibrin clot permeability (Ks), turbidity measurements and clot lysis time were evaluated ⩾5 months after a thrombotic event. The primary composite end point was symptomatic recurrent venous thromboembolism, ischaemic stroke and/or myocardial infarction. During follow-up (median, 62 months; range 46-74 months; 1183.2 patient-years), the primary outcome was observed in 33 (26.2%) APS patients and 16 (15.2%) controls, including 25 (19.8%) and 14 (13.3%) subjects with recurrent venous thromboembolism, respectively. Reduced Ks and prolonged clot lysis time predicted recurrent thromboembolic events in APS patients [per 1 × 10-9 cm2: hazard ratio (HR) = 0.37; 95% CI: 0.24, 0.56; and per 10 min: HR = 1.20; 95% CI: 1.01, 1.40, respectively] and in controls (per 1×10-9 cm2: HR = 0.23; 95% CI: 0.11, 0.42; and per 10 min: HR = 1.51; 95% CI: 1.08, 2.16, respectively). A multivariate analysis showed that positive IgG and IgM anti-β2 glycoprotein I antibodies, withdrawal of anticoagulation, lower platelet count and reduced Ks predicted thromboembolic events in APS patients. Formation of denser fibrin networks could be a novel risk factor for recurrent thromboembolism in APS, which highlights the importance of fibrin phenotype in thrombotic disorders.

Altered Plasma Clot Properties and Trauma-Related Venous Thromboembolism despite Thromboprophylaxis.

Prothrombotic clot phenotype may characterize patients developing deep vein thrombosis (DVT) despite pharmacological thromboprophylaxis. We studied the role of fibrin clot properties and its potential determinants in individuals who experienced DVT after lower limb injury. In a case-control study, we assessed 50 patients who developed DVT despite prophylactic use of low-molecular-weight heparins (the failed thromboprophylaxis group) after a lower limb injury, and three age- and sex-matched control groups, 50 patients each: (1) patients with trauma-related DVT without prior thromboprophylaxis; (2) individuals with unprovoked DVT; (3) patients without history of DVT (the no-DVT controls). Fibrin clot properties, along with thrombin concentration and α2-antiplasmin, were assessed following 3 months of anticoagulation in all DVT patients. Compared with the no-DVT controls, the failed thromboprophylaxis group exhibited denser fibrin networks (12.8% lower clot permeability [Ks], p = 0.0008) and impaired fibrinolysis (46.2% longer clot lysis time [CLT], p = 0.0001 and 8% lower rate of D-dimer release from clots, p = 0.0008). In the unprovoked DVT, similar Ks and 14.9% shorter CLT (p = 0.02) were reported compared with the failed thromboprophylaxis group. The failed thromboprophylaxis patients had higher odds of having elevated peak thrombin generation (>241.5 nM, 90th percentile in the no-DVT controls; odds ratio [OR]: 3.62; 95% confidence interval [CI], 1.86-7.06; p = 0.002), and higher odds of having elevated α2-antiplasmin (>115.05%; OR: 3.38; 95% CI, 1.64-6.98; p = 0.001). Patients who experienced DVT despite thromboprophylaxis following lower limb trauma display a strongly prothrombotic fibrin clot phenotype, including increased clot density and hypofibrinolysis associated with higher plasma α2-antiplasmin.

Altered plasma clot properties increase the risk of recurrent deep vein thrombosis: a cohort study

AbstractIt has been demonstrated that fibrin clots generated from plasma samples obtained from patients with prior thromboembolic events are denser and less susceptible to lysis. Such a prothrombotic fibrin clot phenotype has been suggested as a new risk factor for venous thromboembolism, but its prognostic value is unclear. To assess whether abnormal clot properties can predict recurrent deep vein thrombosis (DVT), we studied 320 consecutive patients aged 18 to 70 years following the first-ever DVT. Plasma clot properties were evaluated after 3 months of anticoagulant treatment since the index event. A mean duration of anticoagulation was 10 months (range, 4-20). Recurrent DVT was observed in 77 patients (25%; 6.6%/year) during a median follow-up of 44 months. Recurrences of DVT were associated with faster formation (−9% lag phase) of denser fibrin networks (−12% fibrin clot permeability [Ks]) and 4% higher maximum absorbance of plasma clots that displayed impaired fibrinolytic degradation (+25% prolonged clot lysis time [CLT]) and a 5% slower rate of increase in D-dimer levels during clot degradation (D-Drate; all P < .05). Proximal DVT alone, higher C-reactive protein, D-dimer, peak thrombin, lower Ks, shorter lag phase, decreased D-Drate, and prolonged CLT were independent predictors of recurrences (all P < .05). Individuals characterized by low Ks (≤7.3 × 10−9 cm2) and prolonged CLT (>96 min) were at the highest risk of recurrent DVT (odds ratio, 15.8; 95% confidence interval, 7.5-33.5). Kaplan-Meier curves showed that reduced Ks and prolonged CLT predicted recurrent DVT. We demonstrate that unfavorably altered clot properties may predict recurrent DVT after anticoagulation withdrawal.

Plasma fibrin clot structure and thromboembolism: clinical implications.

Fibrin formed as a result of fibrinogen polymerization is the main protein component of a clot in a test tube and intravascular thrombi in vivo. Fibrin clot structure characterized by fiber diameter and pore size differs between healthy persons and those with thromboembolic diseases, in part due to the quality and quantity of fibrinogen and the magnitude of thrombin generation. A key measure of plasma clot structure is its permeability, reflected by the Darcy constant (Ks). Reduced Ks is a typical feature of the prothrombotic fibrin clot phenotype, which is associated with faster formation of denser fibrin mesh, relatively resistant to lysis. Low Ks has been reported in patients with prior or acute myocardial infarction (MI), stroke, or venous thromboembolism (encompassing deep vein thrombosis [DVT] and pulmonary embolism [PE]), as well as in those with prothrombotic conditions (eg, in several thrombophilic states) and in the presence of cardiovascular risk factors (eg, obesity). Antithrombotic and anticoagulant agents, along with statins, have been shown to increase Ks. Growing evidence indicates associations between the properties of plasma fibrin clots and morphology of intravascular thrombi in patients with MI. Recently, reduced Ks has been shown to predict recurrent thromboembolic episodes in patients with a history of stroke, PE, DVT, and their serious complications, including postthrombotic syndrome and thromboembolic pulmonary hypertension. We discuss the current evidence for the significance of clot density measured in vitro as a prognostic marker in a number of clinical conditions associated with elevated thromboembolic risk.

Prothrombotic Fibrin Clot Phenotype in Patients with Deep Vein Thrombosis and Pulmonary Embolism: A New Risk Factor for Recurrence.

Prothrombotic fibrin clot phenotype, involving faster formation of dense meshwork composed of thinner and highly branched fibers that are relatively resistant to plasmin-induced lysis, has been reported in patients with not only myocardial infarction or stroke, but also venous thromboembolism (VTE), encompassing deep vein thrombosis (DVT), and/or pulmonary embolism (PE). Prothrombotic fibrin clot phenotype, in particular prolonged clot lysis time, is considered a novel risk factor for VTE as well as venous thrombosis at unusual location, for example, cerebral sinus venous thrombosis, retinal vein obstruction, and Budd-Chiari syndrome. Growing evidence from observational studies indicates that abnormal fibrin clot properties can predict recurrent DVT and PE and they are involved in serious complications of VTE, for example, thromboembolic pulmonary hypertension and postthrombotic syndrome. The purpose of this article is to review our current understanding of the role of fibrin clot structure and function in venous thrombosis with emphasis on clinical issues ranging from prognosis to therapy.

Plasma fibrin clot properties in the G20210A prothrombin mutation carriers following venous thromboembolism: the effect of rivaroxaban.

We sought to investigate whether the G20210A prothrombin mutation modifies plasma fibrin clot properties in patients after venous thromboembolism (VTE) and how rivaroxaban treatment affects these alterations. We studied 34 prothrombin mutation heterozygous carriers and sex- and age-matched 34 non-carriers, all at least three months since the first VTE episode, before and during treatment with rivaroxaban. Clot permeability (Ks) and clot lysis time (CLT) with or without elimination of thrombin activatable fibrinolysis inhibitor (TAFI) were assessed at baseline, 2-6 hours (h) after and 20-25 h after intake of rivaroxaban (20 mg/day). At baseline, the prothrombin mutation group formed denser clots (Ks -12 %, p=0.0006) and had impaired fibrinolysis (CLT +14 %, p=0.004, and CLT-TAFI +13 %, p=0.03) compared with the no mutation group and were similar to those observed in 15 healthy unrelated prothrombin mutation carriers. The G20210A prothrombin mutation was the independent predictor for Ks and CLT before rivaroxaban intake. At 2-6 h after rivaroxaban intake, clot properties improved in both G20210A carriers and non-carriers (Ks +38 %, and +37 %, CLT -25 % and -25 %, CLT-TAFI -20 % and -24 %, respectively, all p<0.001), but those parameters were worse in the prothrombin mutation group (Ks -12.8 %, CLT +17 %, CLT-TAFI +13 %, all p<0.001). Rivaroxaban concentration correlated with fibrin clot properties. After 20-25 h since rivaroxaban intake most clot properties returned to baseline. Rivaroxaban-related differences in clot structure were confirmed by scanning electron microscopy images. In conclusion, rivaroxaban treatment, though improves fibrin clot properties, cannot abolish more prothrombotic fibrin clot phenotype observed in prothrombin mutation carriers following VTE.

Prothrombotic Fibrin Clot Phenotype Is Associated With Recurrent Pulmonary Embolism After Discontinuation of Anticoagulant Therapy.

Pulmonary embolism (PE) is a life-threatening manifestation of venous thromboembolism with a high recurrence rate after anticoagulation cessation. Recently, we have reported that prothrombotic clot phenotype in venous thromboembolism patients is associated with an increased risk of recurrent deep-vein thrombosis. We tested whether abnormal clot properties are predictive of recurrent PE. We investigated 156 consecutive white patients aged 18 to 65 years after the first-ever provoked or unprovoked PE (n=89), with or without deep-vein thrombosis. Plasma fibrin clot permeability (Ks), turbidity measurements, calibrated automated thrombography, and efficiency of fibrinolysis using clot lysis time, maximum D-dimer levels, and rate of increase in D-dimer levels were evaluated at ≥3 months of anticoagulant therapy, at least 4 weeks since the anticoagulation withdrawal. The primary end point was recurrent PE during a median follow-up of 50 months. Recurrent PE was diagnosed in 23 (14.7%; 5%/yr) patients. Recurrent PE was associated with formation of denser fibrin networks reflected by lower Ks (P=0.007) and impaired fibrinolysis, as evidenced by prolonged clot lysis time (P=0.012) and reduced maximum rate of increase in D-dimer levels in the lysis assay (P=0.004). Patients with recurrent PE had higher plasma D-dimer (P<0.001) and thrombin peak (P=0.007) compared with the remainder, whereas turbidity measurements and maximum D-dimer levels did not differ in the recurrence. Multivariate model showed that independent predictors of recurrent PE were female sex, unprovoked venous thromboembolism, higher plasma D-dimer, reduced Ks, and reduced maximum rate of increase in D-dimer levels in the lysis assay (all P<0.05). Altered fibrin clot properties including formation of more compact clots displaying impaired susceptibility to lysis may predispose to recurrent PE.

Unfavorably Altered Fibrin Clot Properties in Patients with Eosinophilic Granulomatosis with Polyangiitis (Churg-Strauss Syndrome): Association with Thrombin Generation and Eosinophilia.

ObjectivesGiven reports on the increased prevalence of thromboembolic incidents in patients with eosinophilic granulomatosis with polyangiitis (EGPA; Churg-Strauss syndrome), we investigated whether fibrin clot properties are unfavorably altered in EGPA.MethodsEx vivo plasma fibrin clot characteristics, including clot permeability, turbidimetry and efficiency of fibrinolysis using two assays, were investigated in 34 consecutive patients with remission in EGPA according to the Birmingham Vasculitis Activity Score version 3 (23 female, 11 male), aged 48 (range, 21–80) years. The control group comprised 34 age- and sex- matched volunteers.ResultsCompared with controls, patients with EGPA were characterized by denser fiber clots (estimated pore size, Ks, 7.30±0.93 vs 10.14±1.07 10−9 cm2), faster fibrin polymerization (lag phase in a turbidimetric curve, 41.8±3.6 vs 47.4±2.9 s), thicker fibrin fibers (maximum absorbance, ΔAbs, 0.87±0.09 vs 0.72±0.07), higher maximum levels of D-dimer released from clots (DDmax 4.10±0.46 vs 3.54±0.35 mg/L), and prolonged clot lysis time (t50%; 9.50±1.45 vs 7.56±0.87 min); all p<0.0001. Scanning electron microscopy images confirmed denser plasma fibrin networks composed of thinner fibers formed in EGPA. Antineutrophil cytoplasmic antibody status and C-reactive protein did not affect clot variables. Multivariate analysis adjusted for fibrinogen showed that Ks was predicted by eosinophil count, peak thrombin generation, factor VIII, and soluble CD40 ligand, whereas eosinophil count, peak thrombin generation and antiplasmin predicted t50%.ConclusionThis study is the first to show that EGPA is associated with prothrombotic plasma fibrin clot phenotype, which may contribute to thromboembolic manifestations reported in this disease.

Plasma fibrin clot phenotype independently affects intracoronary thrombus ultrastructure in patients with acute myocardial infarction.

Determinants of intracoronary thrombus (ICT) composition in patients with ST-elevation myocardial infarction (STEMI) are largely unknown. We sought to investigate whether plasma fibrin phenotype and platelet reactivity affect ICT ultrastructure. We assessed the content of fibrin, platelets and erythrocytes including polyhedrocytes by scanning electron microscopy on the surface and inside ICT aspirated from 80 STEMI patients within 12 hours since chest pain onset. Plasma fibrin clot permeability (Ks), which indicates the average pore size, lysis time (t50 %), platelet reactivity index (PRI) and ADP-induced platelet aggregation (ADP5, 20µM) were evaluated on admission. All patients received aspirin and 45 (56.3 %) 600 mg of clopidogrel, 80 (60-120) min prior to aspiration. Higher content of fibrin (61.6 vs 34.3 %, P< 0.0001) and platelets (8.2 vs 4.8 %, P=0.018) and lower erythrocyte content (15.8 vs 42.9 %, P< 0.0001) were found on ICT surface compared with its inner part. After adjustment for fibrinogen, in both ICT parts fibrin content was correlated with Ks (r≤-0.55, P< 0.0001) and t50 % (r≥ 0.29, P≤ 0.02) but not with PRI and ADP5,20µM. Polyhedrocytes were observed in 16 (20 %) patients and their large amount expressed as ≥ 50 % fields of view covered by polyhedrocytes was associated with the lower PRI values (40 vs 69 %, P=0.015), but not Ks or t50 %. By multivariate regression, Ks (β=-0.62, P< 0.0001), clopidogrel pretreatment (β=-0.36, P< 0.001), ischemia time (β=0.19, P=0.044) and family history (β=0.18, P=0.049) independently predicted fibrin content in the whole ICT (R²=0.65, P< 0.0001). Formation of denser plasma fibrin clots is independently associated with high fibrin content within the ICT in STEMI.