Hyperglycemia Is Associated With Enhanced Thrombin Formation, Platelet Activation, and Fibrin Clot Resistance to Lysis in Patients With Acute Coronary Syndrome

OBJECTIVE—Acute hyperglycemia on admission for acute coronary syndrome worsens the prognosis in patients with and without known diabetes. Postulated mechanisms of this observation include prothrombotic effects. The aim of this study was to evaluate the effect of elevated glucose levels on blood clotting in acute coronary syndrome patients

Impaired endogenous fibrinolysis at high shear using a point-of-care test in STEMI is associated with alterations in clot architecture

© The Author(s) 2019Impaired endogenous fibrinolysis is an adverse prognostic biomarker in acute coronary syndrome (ACS). Abnormally dense in vitro fibrin thrombi have been demonstrated in ACS patients and related to hypofibrinolysis using cumbersome, laboratory-based methods. We aimed to assess endogenous fibrinolysis using a point-of-care technique and relate this to clot architecture. From patients with ST-segment elevation myocardial infarction (STEMI), venous blood was drawn immediately on arrival to assess thrombotic status. Blood was assessed using the point-of-care Global Thrombosis Test which measures occlusive thrombus formation under high shear and subsequently endogenous fibrinolysis (lysis time, LT). Two samples per patient were run in parallel. In one channel, the measurement was allowed to proceed as normal. In the other, after occlusion, thrombus was extracted, washed, fixed in glutaraldehyde, dried, sputter-coated, and assessed using scanning electron microscope. Endogenous fibrinolysis was strongly associated fibrin fibre thickness (p = 0.0001). As LT increased (less efficient fibrinolysis), the fibrin network of the thrombus was significantly more compact and dense, with thinner fibrin fibres and smaller gaps. Fibrin fibre thickness correlated inversely with LT (r = - 0.89, p = 0.001). Adverse clot architecture in vitro is directly related to impaired endogenous fibrinolysis using a relatively new point-of-care technique in patients with STEMI. This may transform the relevance of fibrin clot architecture from an off-line laboratory association to being directly relevant to endogenous fibrinolysis at the patient bedside, which could be used as a near-patient test to guide prognosis and assess the effect of treatment.Peer reviewedFinal Published versio

Fibrin clot properties independently predict adverse clinical outcome following acute coronary syndrome: a PLATO substudy

Aims: To determine whether fibrin clot properties are associated with clinical outcomes following acute coronary syndrome (ACS). Methods and results: Plasma samples were collected at hospital discharge from 4354 ACS patients randomized to clopidogrel or ticagrelor in the PLATelet inhibition and patient Outcomes (PLATO) trial. A validated turbidimetric assay was employed to study plasma clot lysis time and maximum turbidity (a measure of clot density). One-year rates of cardiovascular (CV) death, spontaneous myocardial infarction (MI) and PLATO-defined major bleeding events were assessed after sample collection. Hazard ratios (HRs) were estimated using Cox proportional hazards models. After adjusting for CV risk factors, each 50% increase in lysis time was associated with CV death/spontaneous MI [HR 1.17, 95% confidence interval (CI) 1.05-1.31; P  0.05). Neither lysis time nor maximum turbidity was associated with major bleeding events. Conclusion: Fibrin clots that are resistant to lysis independently predict adverse outcome in ACS patients. Novel therapies targeting fibrin clot properties might be a new avenue for improving prognosis in patients with ACS

Fibrin structure in organized thrombotic material removed during pulmonary artery endarterectormy : the effect of vessel calibre

Pulmonary endarterectomy (PEA) is a curative therapeutic approach in patients with chronic thromboembolic pulmonary hypertension (CTEPH). The location-dependent structural differences of thrombotic material found in pulmonary arteries in CTEPH are poorly investigated. We present the case of a 47-year-old woman with antiphospholipid syndrome, diabetes mellitus and abnormal fibrin phenotype, who underwent PEA for CTEPH. Intravascular material removed bilaterally during PEA (from lobar, segmental and sub-segmental arteries) has been studied using light and scanning electron microscopy (SEM). Light microscopy showed tighter fibrous network in the portions of intraluminal thrombotic material facing the vessel wall, which contained collagen and fibrin fibers, and abundant cells. Cells, evaluated by immunostaining, were present in the whole removed material. Tissue factor expression was also observed with the highest values in the portions of intravascular material facing the vessel wall. In the main pulmonary arteries, SEM images revealed thick fibers of fibrous proteins loosly meshed and few erythrocytes and platelets between them (both dysmorphic “wedged” and fresh cells were present). In the fibrotic layers, containing mainly collagen and fibrin, removed from the lobar/segmental pulmonary arteries we found a stepwise increase in fiber density with decreasing vessel calibre, followed by denser fibrous networks composed of thinner fibers. Elastic fibers in the lobar and segmental arteries were aligned along the blood flow vector. These findings demonstrate differences in the structure of endarterectomized PEA material dependent on the vessel calibre and might contribute to understanding of CTEPH pathophysiology

Abnormal clot microstructure formed in blood containing HIT-like antibodies

IntroductionThrombosis is a severe and frequent complication of heparin-induced thrombocytopenia (HIT). However, there is currently no knowledge of the effects of HIT-like antibodies on the resulting microstructure of the formed clot, despite such information being linked to thrombotic events. We evaluate the effect of the addition of pathogenic HIT-like antibodies to blood on the resulting microstructure of the formed clot.Materials and methodsPathogenic HIT-like antibodies (KKO) and control antibodies (RTO) were added to samples of whole blood containing Unfractionated Heparin and Platelet Factor 4. The formed clot microstructure was investigated by rheological measurements (fractal dimension; df) and scanning electron microscopy (SEM), and platelet activation was measured by flow cytometry.Results and conclusionsOur results revealed striking effects of KKO on clot microstructure. A significant difference in df was found between samples containing KKO (df = 1.80) versus RTO (df = 1.74; p < 0.0001). This increase in df was often associated with an increase in activated platelets. SEM images of the clots formed with KKO showed a network consisting of a highly branched and compact arrangement of thin fibrin fibres, typically found in thrombotic disease. This is the first study to identify significant changes in clot microstructure formed in blood containing HIT-like antibodies. These observed alterations in clot microstructure can be potentially exploited as a much-needed biomarker for the detection, management and monitoring of HIT-associated thrombosis

Recurrent venous thromboembolism patients form clots with lower elastic modulus than those with non-recurrent disease.

BACKGROUND:Venous thromboembolism (VTE) is associated with a high risk of recurrent events after withdrawal of anticoagulation. OBJECTIVES:The aim of this study was to determine the difference in plasma clot mechanical properties from patients having recurrent (r) versus non-recurrent (nr) VTE. METHODS:We previously developed a system for determining clot mechanical properties using an in-house magnetic tweezers system. This system was used to determine the mechanical properties of clots made from plasma of 11 patients with rVTE and 33 with nrVTE. Plasma was mixed with micrometre-sized beads followed by the addition of thrombin and calcium to induce clotting, then placed in small capillary tubes and allowed to clot overnight. Bead displacements upon manipulation with magnetic forces were analysed to determine clot elastic and viscous moduli. Fibrin clot structure was analysed by turbidimetry and confocal microscopy. FXIII was measured by pentylamine incorporation into fibrin. RESULTS:Clots from rVTE patients showed nearly two-fold less elastic and less viscous moduli than clots from nrVTE patients, regardless of male sex, unprovoked events, family history of VTE, fibrinogen concentration or BMI. No differences were observed in clot structure, fibrinolysis rates or FXIII levels. CONCLUSION:Using magnetic tweezers for the first time in patient samples, we found that plasma clots from rVTE patients demonstrated reduced elastic modulus and reduced viscous modulus when compared with nrVTE patients. These data indicate a possible role for fibrin clot visco-elastic properties in determining VTE recurrence

Recurrent venous thromboembolism patients form clots with lower elastic modulus than those with non-recurrent disease.

BACKGROUND:Venous thromboembolism (VTE) is associated with a high risk of recurrent events after withdrawal of anticoagulation. OBJECTIVES:The aim of this study was to determine the difference in plasma clot mechanical properties from patients having recurrent (r) versus non-recurrent (nr) VTE. METHODS:We previously developed a system for determining clot mechanical properties using an in-house magnetic tweezers system. This system was used to determine the mechanical properties of clots made from plasma of 11 patients with rVTE and 33 with nrVTE. Plasma was mixed with micrometre-sized beads followed by the addition of thrombin and calcium to induce clotting, then placed in small capillary tubes and allowed to clot overnight. Bead displacements upon manipulation with magnetic forces were analysed to determine clot elastic and viscous moduli. Fibrin clot structure was analysed by turbidimetry and confocal microscopy. FXIII was measured by pentylamine incorporation into fibrin. RESULTS:Clots from rVTE patients showed nearly two-fold less elastic and less viscous moduli than clots from nrVTE patients, regardless of male sex, unprovoked events, family history of VTE, fibrinogen concentration or BMI. No differences were observed in clot structure, fibrinolysis rates or FXIII levels. CONCLUSION:Using magnetic tweezers for the first time in patient samples, we found that plasma clots from rVTE patients demonstrated reduced elastic modulus and reduced viscous modulus when compared with nrVTE patients. These data indicate a possible role for fibrin clot visco-elastic properties in determining VTE recurrence

Identification of a variant hotspot in MYBPC3 and of a novel CSRP3 autosomal recessive alteration in a cohort of Polish patients with hypertrophic cardiomyopathy

INTRODUCTION Hypertrophic cardiomyopathy (HCM) is a heart disorder caused by autosomal dominant alterations affecting both sarcomeric genes and other nonsarcomeric loci in a minority of cases. However, in some patients, the occurrence of the causal pathogenic variant or variants in homozygosity, compound heterozygosity, or double heterozygosity has also been described. Most of the HCM pathogenic variants are missense and unique, but truncating mutations of the MYBPC3 gene have been reported as founder pathogenic variants in populations from Finland, France, Japan, Iceland, Italy, and the Netherlands. OBJECTIVES This study aimed to assess the genetic background of HCM in a cohort of Polish patients. PATIENTS AND METHODS Twenty–nine Polish patients were analyzed by a next–generation sequencing panel including 404 cardiovascular genes. RESULTS Pathogenic variants were found in 41% of the patients, with ultra–rare MYBPC3 c.2541C&gt;G (p.Tyr847Ter) mutation standing for a variant hotspot and correlating with a lower age at HCM diagnosis. Among the nonsarcomeric genes, the CSRP3 mutation was found in a single case carrying the novel c.364C&gt;T (p.Arg122Ter) variant in homozygosity. With this finding, the total number of known HCM cases with human CSRP3 knockout cases has reached 3