Letter to the Editor

Reply to: “Procoagulant imbalance in patients with non-alcoholic fatty liver disease”

Patients with cirrhosis have a normal to increased thrombin generation (TG) capacity in platelet-poor plasma (PPP). By reflecting the contribution of all circulating blood cells, whole blood (WB) TG may allow a more physiological assessment of coagulation.

We compared WB-TG vs PPP-TG in patients with cirrhosis.

Assessment of coagulation included routine tests, factor VIII, natural anticoagulants, PPP-TG, and WB-TG. TG assays were performed with and without thrombomodulin. Twenty-five healthy subjects were included as controls.

We included 108 patients (Child-Pugh A/B/C, 44/24/40). Compared with controls, patients had significantly lower platelet count, longer international normalized ratio, higher FVIII, and lower levels of protein C/S and antithrombin. Regarding thrombomodulin-modified TG assays, in compensated cirrhosis, both PPP-TG and WB-TG indicated an increased TG capacity, as reflected by an endogenous thrombin potential (ETP) significantly higher than controls. In contrast, in decompensated cirrhosis, PPP-TG indicated a hypercoagulable state with increased ETP, higher peak height, and shorter time-to-peak than controls, whereas WB-TG revealed a progressive impairment of TG kinetics and total capacity, ultimately resulting in a profound hypocoagulable state in patients with Child-Pugh C cirrhosis (ie, significant prolongation of lag time and time-to-peak with reduction of both ETP and peak height). In decompensated patients, bacterial infections and severity of anemia were associated with a further reduction of both ETP and peak height.

Compensated cirrhosis is associated with an increased TG capacity. In decompensated cirrhosis, contrary to PPP-TG, which indicates hypercoagulability, WB-TG shows a significant hypocoagulable state. The clinical value of these findings deserves further investigation.

Our understanding of the function of the liver has evolved over the centuries. Early theories proposing that the liver could be used to divine the future have been superseded by our current knowledge of the importance of the liver in processes such as digestion and detoxification. Similarly, although liver disease was previously associated with only an increased risk of bleeding, there is now a substantial body of evidence demonstrating an increased thrombotic potential in patients with this disease. Metabolic-associated fatty liver disease (MAFLD) is increasing in frequency and is likely to overtake alcoholic liver disease as the primary indication for liver transplant in the future. In this review, we discuss the evidence linking liver disease, and MAFLD in particular, with arterial and venous thromboembolic disease. We review the safety and efficacy of anticoagulation in advanced liver disease and consider whether antithrombotic agents could slow or halt the progression of fibrosis in MAFLD.

Bacterial infections in cirrhosis are associated with increased bleeding risk. To assess the factors responsible for bleeding tendency in patients with bacterial infections, we conducted a prospective study comparing all 3 aspects of hemostasis (platelets, coagulation, and fibrinolysis) in hospitalized patients with decompensated cirrhosis with vs. without bacterial infections.

Primary hemostasis assessment included whole blood platelet aggregation and von Willebrand factor (VWF). Coagulation assessment included procoagulant factors (fibrinogen, factor II, V, VII, VIII, IX, X, XI, XII, XIII), natural anticoagulants (protein C, protein S, antithrombin) and thrombomodulin-modified thrombin generation test. Fibrinolysis assessment included fibrinolytic factors (plasminogen, t-PA, PAI-1, α2-AP, TAFIa/ai) and plasmin-antiplasmin complex (PAP).

Eighty patients with decompensated cirrhosis were included (40 with and 40 without bacterial infections). Severity of cirrhosis and platelet count were comparable between groups. At baseline, patients with cirrhosis and bacterial infections had significantly lower whole blood platelet aggregation, without significant differences in VWF. Regarding coagulation, bacterial infections were associated with reduced procoagulant factors VII and XII, and a significant reduction of all natural anticoagulants. However, thrombomodulin-modified thrombin generation was comparable between the study groups. Finally, although mixed potentially hypo-fibrinolytic (lower plasminogen) and hyper-fibrinolytic (higher t-PA) changes were present in bacterial infections, a comparable level of PAP was detected in both groups. Upon resolution of infection (n = 29/40), platelet aggregation further deteriorated whereas coagulation and fibrinolysis factors returned to levels observed in patients without bacterial infections.

In hospitalized patients with decompensated cirrhosis, bacterial infections are associated with reduced whole blood platelet aggregation and a significant decrease of all natural anticoagulants, which may unbalance hemostasis and potentially increase the risk of both bleeding and thrombosis.

Bacterial infections are a common issue in hospitalized patients with decompensated cirrhosis (i.e. patients hospitalized due to severe complications of advanced chronic liver disease). Patients with decompensated cirrhosis who acquire infections may be at increased risk of bleeding complications following invasive procedures (that is a procedure in which the body is penetrated or entered, for instance by a needle or a tube). As bleeding complications in decompensated cirrhosis are associated with a high risk of further decompensation and death, there is an urgent need to understand the factors responsible for such increased bleeding tendency. Herein, we investigated the alterations of hemostasis (that is the physiological process responsible for clot formation and stability) in patients with decompensated cirrhosis and bacterial infections. We found that development of bacterial infections in these patients is associated with alterations of hemostasis (particularly of platelets and clotting cascade) that may increase the risk of both bleeding and thrombotic complications.

Cardiovascular disease is the major cause of mortality in non-alcoholic fatty liver disease (NAFLD), a disease affecting one quarter of the world's population. Coagulation imbalance may be a contributing factor but is yet to be convincingly disclosed.

To perform an extensive mapping of the hemostatic system; primary and secondary hemostasis and the fibrinolytic system in non-diabetic NAFLD patients.

Twenty-five non-diabetic, biopsy-proven NAFLD patients [12 simple steatosis; 13 non-alcoholic steatohepatitis (NASH)] investigated by a comprehensive panel of coagulation and fibrinolysis tests in a cross-sectional study. Fifty age- and sex-matched healthy persons served as controls for each of the dynamic analyses: platelet aggregation, thrombin generation, fibrin formation and lysis. Body composition, insulin resistance makers, and liver fat assessed by proton density magnetic resonance imaging were measured in the patients.

Fibrinolytic function was impaired in simple steatosis [median 50% clot lysis time 1123 (min–max, 618–1967) s] and NASH [1448 (521–2618) s] compared to healthy controls [403 (184–1179) s] (p < 0.0001). Plasminogen activator inhibitor-1 (PAI-1) increased stepwise above reference interval from simple steatosis [54 (29–80) ng/ml] to NASH patients [109 (65–153) ng/ml; p = 0.03]. Impaired fibrinolysis correlated with hepatic fat fraction and insulin resistance; PAI-1 correlated with obesity and insulin resistance (ρ ≥ 0.42; p ≤ 0.04). Platelet aggregation, coagulation factors, natural anticoagulants, and thrombin generation were comparable to healthy controls and established reference intervals.

NAFLD patients had impaired fibrinolysis without significant prothrombotic changes in coagulation. The impact of this abnormality on the increased cardiovascular risk remains to be investigated.

It has been suggested that the ratio of procoagulant factor VIII to anticoagulant protein C (FVIII/PC) reflects the hemostatic equilibrium. Moreover, FVIII/PC predicted decompensation/death in a small study not accounting for portal hypertension severity. We investigated (i) the prognostic value of FVIII/PC (outcome-cohort) and (ii) whether FVIII/PC reflects the hypercoagulable state (assessed by thrombomodulin-modified thrombin generation assay [TM-TGA]) or the risk of bleeding/thrombotic events in patients undergoing hepatic venous pressure gradient (HVPG) measurement during follow-up.

(i) The outcome-cohort comprised 576 patients with evidence of advanced chronic liver disease (liver stiffness measurement ≥10 kPa and/or HVPG ≥6 mmHg). (ii) TM-TGA-cohort patients (n = 142) were recruited from the prospective VIenna CIrrhosis Study (VICIS: NCT03267615).

(i) FVIII/PC significantly increased across clinical stages (p <0.001) as well as HVPG (p <0.001) and MELD score (p <0.001) strata and remained independently associated with decompensation/liver-related death (adjusted hazard ratio 1.06; 95% CI 1.01–1.11; p = 0.013), even after multivariable adjustment. It was also associated with acute-on-chronic liver failure (ACLF) development (adjusted hazard ratio 1.10; 95% CI 1.02-1.19; p = 0.015) in patients with decompensated cirrhosis. (ii) FVIII/PC showed a weak positive correlation with endogenous thrombin potential (Spearman’s ρ = 0.255; p = 0.002), but this association disappeared after adjusting for the severity of liver disease. FVIII/PC was not associated with the development of bleeding (p = 0.272) or thrombotic events (p = 0.269). However, FVIII/PC correlated with biomarkers of different pathophysiological mechanisms that promote liver disease progression.

FVIII/PC provides prognostic information regarding hepatic decompensation/death and ACLF, independently of established prognostic indicators. However, this is not evidence that hypercoagulability drives disease progression, as the correlation between FVIII/PC and thrombin generation is confounded by liver disease severity and FVIII/PC was not associated with thrombosis. Therefore, FVIII/PC does not reflect coagulation and results from previous studies on FVIII/PC require re-interpretation.

NCT03267615 (in part).

A balanced coagulation system is essential for preventing bleeding episodes and blood clot formation (thrombosis). Blood of patients with advanced liver disease may have increased coagulation potential, possibly promoting the worsening of liver disease via thrombosis in the blood vessels of the liver. The ratio between the results of 2 blood tests (procoagulant factor VIII to anticoagulant protein C) has been suggested to reflect these increases in coagulation potential. Our study demonstrates, on the one hand, that this ratio is a versatile predictor of the development of complications of cirrhosis, yet on the other hand, that it is unrelated to coagulation.