Preserved hemostatic status in patients with non-alcoholic fatty liver disease.

BACKGROUND & AIMS: Non-alcoholic fatty liver disease (NAFLD) is associated with an increased risk of thrombosis. However, it remains unclear if hypercoagulability contributes to this risk. We, therefore, determined an in-depth hemostatic profile in a cohort of well-defined patients with NAFLD. METHODS: We drew blood samples from 68 patients with biopsy-proven NAFLD (simple steatosis n=24, NASH n=22, and NASH cirrhosis n=22), 30 lean controls, 30 overweight controls (body mass index (BMI) >25kg/m2), and 15 patients with alcoholic (ASH) cirrhosis, and performed in-depth hemostatic profiling. RESULTS: Basal and agonist-induced platelet activation, plasma levels of markers of platelet activation, and plasma levels of the platelet adhesion regulators von Willebrand factor and ADAMTS13 were comparable between patients with non-cirrhotic NAFLD and controls. Agonist-induced platelet activation was decreased in patients with cirrhosis. Thrombomodulin-modified thrombin generation was comparable between all patients and controls, although patients with cirrhosis had a reduced anticoagulant response to thrombomodulin. Thromboelastography test results were comparable between controls and non-cirrhotic NAFLD patients, but revealed moderate hypocoagulability in cirrhosis. Plasma fibrinolytic potential was decreased in overweight controls and non-cirrhotic NAFLD, but accelerated fibrinolysis was observed in ASH cirrhosis. Clot permeability was decreased in overweight controls and patients with NAFLD. CONCLUSIONS: The overall hemostatic profile is comparable between patients with non-cirrhotic NAFLD and controls. Additionally, pro-thrombotic features (hypofibrinolysis and a pro-thrombotic structure of fibrin clot) in patients with NAFLD are likely driven by obesity. Our study suggests a limited role for hyperactive hemostasis in the increased thrombotic risk in NAFLD. LAY SUMMARY: The combined results of this study show that the overall hemostatic status is comparable between healthy individuals and patients with a fatty liver disease.

Vascular Disease in Patients with Nonalcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD) is increasingly being diagnosed and is considered to be the most frequent chronic liver disorder in Western countries. It represents a histopathological spectrum ranging from simple hepatic steatosis to steatohepatitis and finally cirrhosis. NAFLD is considered as the hepatic manifestation of the metabolic syndrome and is associated with increased mortality. Increasing evidence now suggests that NAFLD is also associated with higher cardiovascular disease (CVD) morbidity and mortality independent of conventional cardiometabolic risk factors (such as obesity, insulin resistance, and diabetes mellitus). The exact mechanisms linking NAFLD to increased CVD risk are still incompletely understood and likely reflect multiple coexisting pathways. Recent evidence suggests a contributive effect of an altered hemostasis in patients with NAFLD. For example, patients with NAFLD have higher levels of prothrombotic factors (e.g., von Willebrand factor, fibrinogen, factor VII activity, and plasminogen activator inhibitor-1), which correlate with underlying histological severity of the disease. The current review focuses on these hemostatic abnormalities in NAFLD and the link with increased CVD risk.

Preserved clot formation detected by the Thrombodynamics analyzer in patients with cirrhosis.

INTRODUCTION: Patients with cirrhosis have substantial alterations in their hemostatic system, which are paradoxically associated with the risk of both bleeding and thrombotic complications. However, it still remains difficult to predict those risks, because results from conventional coagulation tests, such as the prothrombin time (PT) and activated partial thromboplastin time (APTT), do not reflect the complex hemostatic changes in these patients. More sophisticated global hemostasis tests, such as thrombin generation assays, are not standardized for routine use yet. Here we examined the spatial clot growth in plasma from patients with cirrhosis using the novel Thrombodynamics assay, which uses a fundamentally new approach to test plasma hemostatic capacity. MATERIALS AND METHODS: Thrombodynamics assays were performed in plasma from thirty-one patients with cirrhosis and twenty-five healthy controls. Results were compared to results with thrombin generation testing and PT/APTT test results. RESULTS: Rates of clot growth, clot size, and clot density from the Thrombodynamics assay were comparable between patients and controls. Thrombin generation in the presence of thrombomodulin was increased in the patients, despite prolonged PT and APTT test results. There was little correlation between parameters derived from the Thrombodynamics assay and the PT, APTT, or thrombin generation data. CONCLUSIONS: The Thrombodynamics assay showed preserved clot formation in plasma from patients with cirrhosis, which is in line with the results of the thrombin generation assay in this study and previously reported by others.

Management of coagulation abnormalities in liver disease.

Liver disease is characterized by changes in all phases of hemostasis. These hemostatic alterations were long considered to predispose patients with liver disease towards a bleeding tendency, as they are associated with prolonged conventional coagulation tests. However, these patients may also suffer from thrombotic complications, and we now know that the hemostatic system in patient with liver disease is, in fact, in a rebalanced state. In this review we discuss the concept of rebalanced hemostasis and its implications for clinical management of patients with liver disease. For instance, there is no evidence that the use of prophylactic blood product transfusion prior to invasive procedures reduces bleeding risk. Clinicians should also be aware of the possibility of thrombosis occurring in patients with a liver disease, and regular thrombosis prophylaxis should not be withheld in these patients.

Differential in vitro inhibition of thrombin generation by anticoagulant drugs in plasma from patients with cirrhosis.

BACKGROUND: Treatment and prevention of thrombotic complications is frequently required in patients with cirrhosis. However anticoagulant therapy is often withheld from these patients, because of the perceived bleeding diathesis. As a result of the limited clinical experience, the anticoagulant of choice for the various indications is still not known. OBJECTIVES: We evaluated the in vitro effect of clinically approved anticoagulant drugs in plasma from patients with cirrhosis. PATIENTS/METHODS: Thirty patients with cirrhosis and thirty healthy controls were studied. Thrombin generation assays were performed before and after addition of unfractionated heparin, low molecular weight heparin, fondaparinux, dabigatran, and rivaroxaban, to estimate anticoagulant potencies of these drugs. RESULTS: Addition of dabigatran led to a much more pronounced reduction in endogenous thrombin potential in patients compared to controls (72.6% reduction in patients vs. 12.8% reduction in controls, P<0.0001). The enhanced effect of dabigatran was proportional to the severity of disease. In contrast, only a slightly increased anticoagulant response to heparin and low molecular weight heparin and even a reduced response to fondaparinux and rivaroxaban was observed in plasma from cirrhotic patients as compared to control plasma. CONCLUSIONS: The anticoagulant potency of clinically approved drugs differs substantially between patients with cirrhosis and healthy individuals. Whereas dabigatran and, to a lesser extent, heparin and low molecular weight heparin are more potent in plasma from patients with cirrhosis, fondaparinux and rivaroxaban showed a decreased anticoagulant effect. These results may imply that in addition to dose adjustments based on altered pharmacokinetics, drug-specific dose adjustments based on altered anticoagulant potency may be required in patients with cirrhosis.

Routine coagulation assays underestimate levels of antithrombin-dependent drugs but not of direct anticoagulant drugs in plasma from patients with cirrhosis.

There is increasing recognition that thrombotic complications may occur in patients with cirrhosis, and literature on antithrombotic treatment in these patients is rapidly emerging. Due to extensive haemostatic changes in patients with cirrhosis, careful monitoring of anticoagulant therapy may be required. Recent data suggest that plasma levels of low molecular weight heparin (LMWH) are substantially underestimated by the anti-activated factor X (anti-Xa) assay in patients with cirrhosis. We studied the in vitro recovery of antithrombin (AT)-dependent and -independent anticoagulant drugs in plasma from 26 patients with cirrhosis and 30 healthy controls and found substantially reduced anti-Xa levels when AT-dependent anticoagulant drugs were added to the plasma of patients with cirrhosis. LMWH (0·2 U/ml) had the poorest recovery in plasma from patients with cirrhosis (0·13 ± 0·06 U/ml, compared to 0·23 ± 0·03 U/ml in controls, P < 0·0001), followed by unfractionated heparin and fondaparinux. In contrast, the recovery of rivaroxaban and dabigatran was identical between patients and controls. These data suggest that the anti-Xa assay cannot be used to monitor AT-dependent anticoagulant drugs in patients with cirrhosis, as it substantially underestimates drug levels. The direct factor Xa and IIa inhibitors, however, may be monitored through the respective anti-Xa and anti-IIa assays in patients with cirrhosis.

Decreased tissue factor pathway inhibitor (TFPI)-dependent anticoagulant capacity in patients with cirrhosis who have decreased protein S but normal TFPI plasma levels.

Protein S acts as a cofactor for tissue factor pathway inhibitor (TFPI) in the down regulation of thrombin generation, and acquired and congenital protein S deficiencies are associated with a concomitant TFPI deficiency. In contrast, in patients with liver diseases, decreased protein S, but normal or increased levels of TFPI have been reported. We compared TFPI and protein S plasma levels between 26 patients with cirrhosis and 20 healthy controls and found that TFPI levels were comparable between patients (111 ± 38%) and controls (108 ± 27%), despite reduced protein S levels (74 ± 23% in patients vs. 98 ± 10% in controls). Subsequently, we quantified the activity of the TFPI-protein S system by measuring thrombin generation in the absence and presence of neutralizing antibodies to protein S or TFPI. Ratios of peak thrombin generation in the absence and presence of these antibodies were calculated. Both the protein S and the TFPI ratios were increased in patients with cirrhosis compared to controls. Protein S ratios were (0·62 [0·08-0·93] in patients vs. 0·32 [0·20-0·54] in controls; TFPI ratios were 0·50 [0·05-0·90] in patients vs. 0·18 [0·11-0·49] in controls). Thus, although the acquired protein S deficiency in patients with cirrhosis is not associated with decreased TFPI levels, the TFPI/protein S anticoagulant system is functionally impaired.