1. Introduction
Achieving sustained virological response (SVR) has a significant impact on the natural course of liver disease related to chronic viral C infection. In numerous clinical studies, SVR has been shown to induce the regression of liver fibrosis, the improvement of liver synthesis and, implicitly, the reduction of portal hypertension, which are favorable outcomes in the disease’s progression, changes highlighted primarily in patients with mild or moderate fibrosis [
1,
2,
3].
Another beneficial effect of the eradication of the C virus is brought on by the “reset” of the coagulopathy, an indirect effect that reveres the hypercoagulability status, associated with the cirrhotic patient, by modifying both the procoagulant and anticoagulant factors within close quarters of the normal parameters, thus significantly lowering the hemorrhagic or thrombotic complications [
4,
5].
It is already known that hemostasis in the cirrhotic patient presents some features of coagulation compared to physiological hemostasis, changes that result with the status of advanced liver disease [
6]. Recent studies report that the hepatitis C virus (HCV) additionally influences coagulation status and may cause thrombotic or hemorrhagic complications to occur more frequently in patients with chronic HCV infection [
7]. Inflammation at the vascular level together with altered coagulation secondary to HCV infection are elements that contribute to the increased risk of thromboembolic diseases [
8]. On the other hand, thrombocytopenia and lower levels of clotting factors contribute to an increased risk of bleeding [
9]. Thus, HCV infection is responsible for manifestations of both hypercoagulability and hypocoagulability [
10].
Nielsen et al. are among the few researchers who have specifically investigated, in a prospective study, the hemostatic function of whole blood in patients with chronic HCV infection with varying degrees of liver fibrosis (absent, mild, advanced) treated and without antiviral treatment and the possible effects of viral replication on coagulation [
11].
The effect of HCV viral replication on coagulation parameters was evaluated in the same prospective study involving patients treated with direct antivirals and SVR [
11]. Minor changes in standard post-treatment coagulation parameters were found. Post antiviral treatment, the platelet count and fibrinogen parameters showed a partial “restoration” but at lower values than the control group. The same effect was noticed for the concentration of coagulation factors II – VII – X. Thus, the question arises as to whether the change in coagulation parameters in chronic HCV infection is only a result of viral replication or whether these changes are secondary to liver fibrosis that persists in patients even after SVR is obtained.
The impact of DAAs on coagulation parameters in patients with HCV-related liver cirrhosis is a controversial and intensely studied topic, the realm of which is still not fully explored. Among the first studies to evaluate coagulation parameters during DAAs treatment in patients with HCV infection was the one conducted by Tripodi et al. in 2017 [
4], which investigated coagulation status in HCV-infected patients before, during, and after treatment using traditional global and individual coagulation tests, as well as using state-of-the-art methods, including thrombin generation with and without thrombomodulin, and thromboelastometry as a global method of coagulation status analysis. The authors of the study demonstrated in a prospective study the beneficial effect of DAAs on pro- and anticoagulant factors, by improving pro- and anticoagulant status; DAAs do not substantially alter their balance, but make them more stable and less likely to be disrupted as assumed before treatment [
4].
Data from the literature show that obtaining SVR leads to improved hepatic synthesis of both procoagulant and anticoagulant factors and, implicitly, to a slow recovery of HCV-induced coagulopathy [
4,
5,
12]. At the same time, recent studies have shown that obtaining SVR in patients with HCV-related liver cirrhosis was associated with improved MELD and Child-Pugh scores, which reflect improved hepatic synthesis function and implicitly, synthesis of coagulation factors [
13,
14,
15,
16,
17,
18,
19,
20,
21].
The main objective of this study was to evaluate how coagulation parameters are influenced by the SVR obtained in patients with HCV cirrhosis, treated with AAD therapy and the correlation between the coagulation factors and liver cirrhosis severity.
4. Discussion
The natural course of HCV-related liver disease is significantly impacted by achieving sustained liver disease, due to the improvement in liver function that results from the direct antiviral therapy, effectively bringing the levels of coagulation factors within the normal range, causing a “reset” [
5].
The present study showed that the viral eradication due to the AAD therapy improved liver function by bringing some of the coagulation factors within the normal range, thus bringing a resolution to the hypercoagulable state.
Among the first studies to evaluate coagulation parameters during DAA treatment in C virus-infected patients was that by Tripodi et al. in 2017, who demonstrated in a prospective study the beneficial effect of AAD on pro- and anticoagulant factors [
4]. The authors investigated the coagulation status of HCV-infected patients before, during, and after treatment using traditional global and individual coagulation tests as well as state-of-the-art methods, including thrombin generation with and without thrombomodulin, whose role was previously shown to depict coagulation much more realistically than conventional tests. In addition, thromboelastometry was also used as a global method for analyzing the coagulation status, which graphically translates the entire process of clot formation and continues even after its formation with the evaluation of clot lysis and retraction - the fibrinolytic phase. Thus it was possible to analyze the viscoelastic characteristics of blood, properties already shown to be abnormal in cirrhotic patients. Prothrombin time, thrombin generation with or without thrombomodulin, thromboelastometry, as well as procoagulant (II, VIII, XIII, von Willebrand) and anticoagulant (antithrombin III and protein C) factors were analyzed.
In the present study, the investigated group consisted of patients with viral liver cirrhosis C, the majority being female (68%); the degree of severity of cirrhosis placed the patients mainly in Child-Pugh classes B and C, a fact that attests to the heterogeneity of the study group, which consisted of both compensated and decompensated cirrhotic, with an advanced degree of liver fibrosis.
Most of the patients included in the study, i.e., more than three quarters of them (76%), received treatment with LED/SOF, being the only one recommended and available at that time in our country for the treatment of patients with decompensated HCV or at the limit of hepatic decompensation.
MELD score values decreased significantly in EOT and SVR, data that are consistent with the results obtained in other studies that also demonstrated a significant decrease in liver parameters in patients with SVR [
22]. On the other hand, Krassenburg LAP et al. showed that patients with Child-Pugh B/C cirrhosis had a moderate decrease in MELD score after AAD therapy [
23]. In almost 20% of patients the decrease in MELD score was at least 2 points 12 weeks after the end of therapy. One of the largest studies including 409 patients with decompensated cirrhosis treated with AAD showed a mean ΔMELD 12 of - 0.85 compared with + 0.75 in untreated patients [
24]. However, data from these studies showed no association between ΔMELD 12 and virologic response.
All patients included in the study had undetectable HCV RNA at EOT and SVR. The dramatic decrease in viremia after antiviral treatment also observed in this study is consistent with literature data [
25] and demonstrates that we have included a cohort of patients that can be adapted to any population of cirrhotic patients with HCV infection candidates for antiviral treatment direct.
In this study, we inquired the dynamic changes over time of a wide range of coagulation parameters from the first presentation, at the EOT to the achievement of SVR. Traditional coagulation tests such as platelets, INR, PT, aPTT and individual coagulation factors such as procoagulant factors which include FII, FVIII, FvW (which are known to illustrate important changes in cirrhotic patients) and anticoagulant factors (antithrombin III, protein C, protein S) were monitored during this time period.
Studies in recent years have supported the idea that coagulopathy reflected in particular by prolongation of aPTT, INR and prothrombin type is associated with decreased liver synthesis function. Prothrombin time is a prognostic factor for survival, being an important marker of liver failure [
26].
In the studied group, cirrhotic patients at the time of initiating AAD therapy, presented with a hypocoagulant status, diagnosed by an increased INR, prothrombin time and aPTT, associated with a fibrinogen within the normal range. The normal value of fibrinogen shows that the basic substrate for the thrombin to act exists and so, all coagulation parameters showed a a statistically significant trend towards improvement during the antiviral therapy for most of the patients included in the study.
There was a statistically significant increase in baseline mean platelet count at the end of treatment, a trend that was maintained in both direction and statistical significance (p = 0.000) and at SVR, when the highest platelet counts were achieved. The results of our study are consistent with those reported by Koh et al., who demonstrated in a prospective study of 100 patients followed for 23 months post-SVR that platelet counts improved markedly in patients who achieved SVR [
27]. At the post-treatment evaluation, it was observed that no patient enrolled in the study had an altered prothrombin time. Platelet counts were low (< 160.000/mm
3) in 80% of cirrhotic patients before therapy. At SVR assessment the mean platelet count in the 100 patients increased (from 209.000 to 239.000/mm
3) and was within normal limits in approximately 90% of SVR patients. Before initiation of DAA, platelet counts were normal in patients with no or mild fibrosis, but even in these individuals the mean platelet count increased after SVR was achieved. A significant increase in platelets was observed in patients with moderate to advanced fibrosis. Last but not least, the authors showed that the number of platelets at the time of evaluation of liver elastography by fibroscan is inversely proportional to the degree of liver stiffness [
27].
In the first study on the impact of SVR on coagulation parameters, proposed by Tripodi et al., platelet counts showed no significant improvement at EOT or SVR, while all other coagulation parameters showed an improvement in most patients, with no significant differences between pre- and post-antiviral treatment values, which contrasted the data we obtained [
4]. Additionally, Tripodi et al. showed a decrease in prothrombin time at EOT and 12 weeks from achieving SVR, without statistical significance, which contradicts the data we obtained, where during the follow-up period the PT value registered significant changes.
Moreover, minor changes in standard coagulation parameters post-treatment were reported by another recent study, where platelet count and fibrinogen were partially “restored” post treatment, but below the values expressed in the control group. Furthermore, the concentration of factors II, VII, X was improved after antiviral treatment but to lower values than those of the control group despite obtaining SVR. These data differ from what our study illustrated, where the value of FII reached normal limits by increasing significantly at the time of SVR compared to the initial one.
In this study, it was observed that the average value of the usual parameters of coagulation, at all 3 moments, varied differently according to the Child-Pugh score, their number being inversely proportional to the severity of liver damage. Nielsen et al. are among the few researchers who specifically investigated, in a prospective study, the hemostatic function of whole blood in patients with chronic HCV infection with different degrees of liver fibrosis (absent, mild, advanced), with and without antiviral treatment, and the possible effects of viral replication on coagulation [
11]. Compared with the control group of healthy patients, patients with chronic HCV infection with both mild and advanced fibrosis had thrombocytopenia and low antithrombin III concentration, which predisposes to thrombosis. At the same time, an increase in platelet aggregation was observed in patients with advanced fibrosis compared to those without or with mild liver fibrosis, a phenomenon that explains the occurrence of thrombotic events in patients with chronic HCV infection and increased fibrosis. At the same time, fibrinogen and aPTT values were decreased in the case of HCV infection, but their values did not differ according to the degree of liver fibrosis [
11].
At the same time, recent studies that demonstrated an improvement in the number of platelets after AAD treatment raise an alarm signal in the case of these patients, this phenomenon being considered a predictive factor for triggering a thrombotic event [
28,
29,
30,
31]. Campello E et al., in a prospective study that included 58 patients with HCV cirrhosis treated with DAAs, mention that an increase in the number of platelets post-SVR is at the same time a risk factor for the occurrence of thrombotic complications in patients with more severe liver disease and portal hypertension [
32]. In the studied group the authors reported 3 patients with Child B who developed non-malignant PVT one year after the end of antiviral treatment [
32]. During our study, none of the patients developed thrombotic or hemorrhagic complications, but the follow-up period was short.
In the studied group, it was noted that the activity of all procoagulant factors was modified at the initiation of antiviral treatment. The activity for factor II was decreased while increased values of the activity of factor VIII and factor von Willebrand were recorded, the picture that defines the hypercoagulable status in cirrhotic patients at risk of thrombotic accidents. But over the course of the study, a statistically significant improvement in SVR was observed in these factors with increasing FII and decreasing factor VIII, as well as factor von Willebrand which followed a similar trend.
Similar to the evolution of procoagulant factors, in the case of anticoagulant factors (PC, PS, ATIII) a significant improvement in values was noted in patients with a sustained virological response. PC, PS and AT III values systematically increased over time, from the initial assessment (characteristic of a hypocoagulant status) to the other two determinations, reaching a significant value at the time of SVR. The exact reasons for the reduction in procoagulant imbalance are not definitely known, but the reduction in factor VIII concomitant with the increase in protein C following AAD treatment may be a likely explanation. Moreover, the simultaneous increase in AT III after treatment may contribute to the reduction of this procoagulant imbalance.
The results of clinical trials have shown that high levels of factor vW are a distinct feature of patients with liver cirrhosis. In this study we demonstrated that factor vW decreased in patients treated with antivirals, a fact that can be considered secondary to the beneficial effect of this therapy.
The results of our study are confirmed by those obtained by Tripodi (130), who demonstrated that FII, PC, and AT III increased significantly at EOT and persisted at SVR. Factor VIII concentration registered a statistically significant (p < 0.005) progressive decrease from EOT to SVR. The factor vW level decreased at the end of treatment, reaching statistical significance at SVR.
Russo et al. obtained the same results [
5], showing that a decrease in FVIII and an increase towards normal values of protein C levels were the most significant changes in coagulation parameters. Moreover, an increase in FII, AT III and PS that highlights the improvement of pro- and anticoagulant factors liver synthesis in SVR patients was demonstrated. On the other hand, Nielsen et al. [
11] observed that patients with chronic HCV infection treated with AAD and SVR had partial normalization of coagulation factors II, VII, and X.
The exact reasons why direct antivirals are effective in ameliorating pro- and anticoagulant factors in patients with HCV infection and SVR are not fully understood. It is known for certain that the synthesis of coagulation factors is impaired in cirrhotic patients, but the hypothesis that coagulation factors in SVR patients may also be low due to accelerated viral clearance cannot be excluded. Viral C infection activates coagulation through the mediation of proinflammatory cytokines, which leads to an acceleration of the clearance of coagulation factors from the bloodstream (110). Therefore, it can be assumed that HCV may act directly (decreased liver synthesis capacity) and/or indirectly (accelerated clearance of coagulation factors) on patients with HCV infection. In a recent study Meissner et al. (326) showed that there is a normalization of cytokines in patients with HCV infection treated with SOF/RBV, but their effect on coagulation factors was not studied.