Assessment of endogenous fibrinolysis in clinical using novel tests - Ready for clinical roll-out?

© The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.The occurrence of thrombotic complications, which can result in excess mortality and morbidity, represent an imbalance between the pro-thrombotic and fibrinolytic equilibrium.The mainstay treatment of these complications involves the use of antithrombotic agents but despite advances in pharmacotherapy, there remains a significant proportion of patients who continue to remain at risk.Endogenous fibrinolysis is a physiological counter-measure against lasting thrombosis and may be measured using several techniques to identify higher risk patients who may benefit from more aggressive pharmacotherapy. However, the assessment of the fibrinolytic systemis not yet accepted into routine clinical practice.In this review, we will revisit the different methods of assessing endogenous fibrinolysis (factorial assays, turbidimetric lysis assays, viscoelastic and the global thrombosis tests), including the strengths, limitations, correlation to clinical outcomes of each method and howwe might integrate the assessment of endogenous fibrinolysis into clinical practice in the future.Peer reviewedFinal Published versio

A case of mitochondrial cardiomyopathy with restrictive transmitral filling pattern

Kazunori Otsui, Nobutaka Inoue, Anna Tamagawa, Kazuo OnishiDepartment of Cardiovascular Medicine, Kobe Rosai Hospital, Kobe, JapanAbstract: A 61-year-old diabetic woman with a mitochondrial A3243G mutation was hospitalized for evaluation of breathlessness, general fatigue, and leg edema. Chest radiography revealed cardiomegaly with massive pleural effusion. Serum lactate, pyruvate, and brain natriuretic peptide concentrations were elevated. Transthoracic echocardiography revealed a restrictive pattern of transmitral flow, although systolic function of the left ventricle was only mildly impaired. Based on these findings and her clinical course, the patient was diagnosed with right-sided heart failure caused by mitochondrial cardiomyopathy associated with a restrictive transmitral filling pattern. Treatment with furosemide, enalapril, and eplerenone was effective, and improvement in her symptoms was associated with amelioration of transthoracic echocardiographic findings and a reduction in serum brain natriuretic peptide levels. Previous reports have indicated heterogeneity in the clinical features of mitochondrial cardiomyopathy in patients carrying the A3243G mutation; the present case highlights the substantial variability in the clinical features of this disease.Keywords: mitochondrial disease, A3243G mutation, diastolic dysfunction, transmitral flo

Global Thrombosis Test (GTT) can detect major determinants of haemostasis including platelet reactivity, endogenous fibrinolytic and thrombin generating potential

BACKGROUND: Detection of both thrombosis and bleeding risk are essential in clinical cardiology. Thrombin generated by activated platelets and from the extrinsic coagulation pathway is the major determinant of thrombogenesis and hemostasis. Although novel oral anticoagulants further increase the bleeding risk of antiplatelet drugs, platelet function tests do not reliably predict hemorrhagic complications. It seems that in addition to platelet aggregation, true assessment of bleeding risks requires the measurement of both platelet and plasma derived thrombin activity. OBJECTIVE: To adapt a novel, near-patient test for the assessment of both antithrombotic and anticoagulant effects of oral thrombin inhibitors. METHODS: The point-of-care Global Thrombosis Test (GTT), which measures platelet reactivity to shear-activation in native blood, was used. Thrombin, generated from activated platelets (procoagulant activity) plays a pivotal role in GTT measurement. In order to assess endogenous thrombin potential, in a separate blood sample thrombin generation was induced by microparticles formed during hypotonic hemolysis. Thus two blood samples were tested to measure simultaneously platelet reactivity (occlusion time, OT) and hemolysis (microparticles)-induced endogenous thrombin potential (OT-H). RESULTS: In healthy subjects (n=32), OT measured in native blood was reduced in hemolysed blood (100% vs. 43±4%; OT vs. OT-H respectively). Shortening of OT in hemolysed blood (OT-H) was dose-dependently inhibited by the in vitro added thrombin inhibitor argatroban. In patients receiving dabigatran (n=27), OT and, to a lesser extent, OT-H was prolonged, compared to healthy volunteers. Intra-assay variation of OT-H was low (4.5%), but interindividual variation was great, both in healthy subjects (61%) and in patients on dabigatran (65%). Thrombin inhibitors argatroban, heparin (in vitro) and dabigatran (in vivo) all prolonged both OT and OT-H. There was no correlation between the measured OT and OT-H data. CONCLUSIONS: Microparticles shed from erythrocytes during hypotonic lysis of native blood considerably shortened OT. In a direct proportion to the applied concentrations, various thrombin inhibitors prolonged both OT (antithrombotic effect) and to a lesser extent, OT-H (anticoagulant effect). Further large studies are required to evaluate the usefulness of this technique in a clinical setting, in assessing the anticoagulant and antithrombotic effects of medication and relating GTT results with observed thrombotic and bleeding events.Peer reviewe