Impact of Deficiency of Intrinsic Coagulation Factors XI and XII on Ex Vivo Thrombus Formation and Clot Lysis

Factor XI deficiency: phenotypic age-related considerations and clinical approach towards bleeding risk assessment

ABSTRACT

Factor XI (FXI) deficiency is a rare bleeding disorder that presents complex challenges in patient assessment and bleeding risk management. Despite generally causing mild to moderate bleeding symptoms, clinical manifestations can vary, and bleeding tendency does not always correlate with FXI plasma levels or genotype. Our manuscript delves into the age-related nuances of FXI deficiency across an individual's lifespan. We emphasize issues faced by specific groups, including neonates and females of reproductive age experiencing abnormal uterine bleeding and postpartum hemorrhage. Older patients present unique challenges and concerns related to the management of bleeding as well as thrombotic complications. The current assortment of diagnostic laboratory assays shows limited success in predicting bleeding risk in the perisurgical setting of patients with FXI deficiency. This review explores the intricate interplay between individual bleeding profiles, surgical sites, and FXI activity levels. We also evaluate the accuracy of existing laboratory assays in predicting bleeding and discuss the potential role of investigational global assays in perioperative assessment. Furthermore, we outline our suggested diagnostic approach to refine treatment strategies and decision making. Available treatment options are presented, including antifibrinolytics, replacement products, and recombinant activated FVII. Finally, we discuss promising nonreplacement therapies for the treatment of rare bleeding disorders that can potentially address the challenges faced when managing FXI deficiency-related bleeding complications.

Effect of Three-Day Atorvastatin Administration on Coagulation Factors in Patients With Prior Venous Thromboembolism and Healthy Subjects: A Preliminary Study

ABSTRACT

Statins exert antithrombotic effects, which might contribute to reduced risk of venous thromboembolism (VTE). Rosuvastatin 20 mg/d administered for 4 weeks has been reported to decrease coagulation factors (F) VII, FVIII, and FXI in VTE patients. Moreover, in accordance with recent registry data in non-VTE subjects, statins usage was associated with lower FXI. We investigated whether 3 doses of a statin decrease coagulation factors activity and if such changes can alter fibrin clot properties in VTE patients and healthy subjects. We enrolled 28 consecutive first-ever prior VTE patients after 6 months of anticoagulation and 25 healthy controls well-matched for demographics and lipid profiles (aged 44 [interquartile range 34-51] years) in an interventional nonrandomized study. Before and after 3 doses of atorvastatin 40 mg/d, activity of FVII, FVIII, FIX, and FXI was measured, along with fibrin clot properties, including permeability (Ks) and clot lysis using 3 various assays. After a 3-day statin administration, we observed the decrease of FVII (by 6.2%, P = 0.046) and FXI (by 8.6%, P = 0.044), irrespective of low-density lipoprotein cholesterol reduction (by 24%, P < 0.001), whereas other coagulation factors remained unaltered. Reduction of FVII and FXI activity was inversely correlated with Ks alterations (R = -0.292, P = 0.034 and R = -0.335, P = 0.014, respectively). After adjustment for age, studied group, and fibrinogen level, the reduction of FXI was independently associated with an increase of fibrin clot permeability (B = -0.084, P = 0.027). In conclusion, a 3-day 40 mg atorvastatin administration is sufficient to reduce FVII and FXI activity in our pilot study, which is associated with favorable fibrin clot properties modification.

"Familial Multiple Coagulation Factor Deficiencies of FXI and FXII in an Asymptomatic Saudi Woman"

Factor XI deficiency (FXI) is the third most common coagulation factor deficiency after hemophilia A and B, ie, in the hierarchy after factors VIII and IX, taking into account von Willebrand's factor deficiency, as bleeding disorders are higher than in hemophilia C. Factor XII deficiency (FXII) is a congenital condition, inherited in the vast majority of cases in an autosomal recessive manner, more often associated with thromboembolic complications. A combination of both factor deficiencies has been found very rarely, and it can be familial multiple coagulation factor deficiency (FMCFD). This study reports the case of a 39-year-old woman from Saudi Arabia who had the combination of FXI and FXII deficiencies, known to be on treatment for hypothyroidism and was referred to a hematology clinic with an incidental finding of prolonged activated partial thromboplastin time (aPTT). Although there was no history of bleeding tendency, her siblings had a family history of an unknown type of bleeding disorder. On physical examination, the patient did not show any bruising, petechiae, or ecchymosis. The aPTT was 69 seconds (27-38) with normal use of other hemostatic agents and was corrected after a 50:50 mixing study. Intrinsic coagulation factors were evaluated, and they revealed severe FXI and moderate FXII deficiencies. Due to a strong family history, the patient was diagnosed with FMCFD. In conclusion, familial combined multiple clotting factor deficiency (FCMFD) is a rare condition that requires attention and reporting. The management strategy in such cases has not been well studied, especially in the long-term symptomatic patient with severe but asymptomatic combined FXI and FXII deficiencies, which is an area for review and further study.

Low-Molecular-Weight Heparin Resistance and Its Viscoelastic Assessment in Critically Ill COVID-19 Patients

Critically ill COVID-19 patients present an inflammatory and procoagulant status with a high rate of relevant macro- and microvascular thrombosis. Furthermore, high rates of heparin resistance have been described; yet, individualized anticoagulation by drug monitoring has not been sufficiently researched. We analyzed data from critically ill COVID-19 patients treated at Innsbruck Medical University Hospital with routinely adapted low-molecular-weight heparin (LMWH) doses according to anti-Xa peak levels, and regularly performed ClotPro analyses (a viscoelastic hemostatic whole blood test). A total of 509 anti-Xa peak measurements in 91 patients were categorized as below (<0.008 IU/mL/mg), within (0.008-0-012 IU/mL/mg) or above (> 0.012 IU/mL/mg) expected ranges with respect to the administered LMWH doses. Besides intergroup comparisons, correlations between anti-Xa levels and ClotPro clotting times (CTs) were performed (226 time points in 84 patients). Anti-Xa peak levels remained below the expected range in the majority of performed measurements (63.7%). Corresponding patients presented with higher C-reactive protein and D-dimer but lower antithrombin levels when compared with patients achieving or exceeding the expected range. Consequently, higher enoxaparin doses were applied in the sub-expected anti-Xa range group. Importantly, 47 (51.6%) patients switched between groups during their intensive care unit (ICU) stay. Anti-Xa levels correlated weakly with IN test CT and moderately with Russell's viper venom (RVV) test CT. Critically ill COVID-19 patients present with a high rate of LMWH resistance but with a variable LMWH response during their ICU stay. Therefore, LMWH-anti-Xa monitoring seems inevitable to achieve adequate target ranges. Furthermore, we propose the use of ClotPro's RVV test to assess the coagulation status during LMWH administration, as it correlates well with anti-Xa levels but more holistically reflects the coagulation cascade than anti-Xa activity alone.

Factor XII deficiency evaluated by thrombin generation assay

INTRODUCTION

Coagulation factor XII (FXII) plays a role in thrombin generation, fibrinolysis, inflammation, angiogenesis, chemotaxis and diapedesis. FXII deficiency is not associated with bleeding risk unlike other coagulation factors.

MATERIALS/METHODS

We investigated thrombin generation assay (TGA) profile modification in FXII deficiency and the correlation with TGA and deficiency severity. TGA was performed in platelet poor plasma (PPP) with tissue factor (1 pmol/L) and phospholipid (4 µmol/L) standardized concentration. Thrombin generation profiles were compared in 54 patients with FXII deficiency, 25 healthy controls and 23 patients with hemophilia A (factor VIII (FVIII) deficiency. Patients with FXII deficiency were classified in three groups based on FXII activity (30-50%, 10-29%, <10%). FVIII deficiency was included as a bleeding control group.

RESULTS

As expected, we found a correlation between FXII deficiency and activated partial thromboplastin time (aPTT). A decrease of thrombin generation was observed in healthy controls and all FXII deficiency groups. A decrease of endogenous thrombin potential (ETP), peak and velocity was observed in patients with FVIII deficiency compared to FXII deficiency. A decrease of thrombin generation was noted in patients with FXII deficiency and bleeding history compared to patients with FXII deficiency and thrombosis history.

CONCLUSION

In this study, thrombin generation profiles were not sensitive to FXII deficiency. TGA could distinguish bleeding and thrombotic tendency in FXII deficiency. Our results should therefore be considered as exploratory and deserve confirmation.

Viscoelastic testing in benign hematologic disorders: Clinical perspectives and future implications of point-of-care testing to assess hemostatic competence

Viscoelastic tests (VETs) have been used routinely for liver transplantation, cardiac surgery, and trauma, but only recently have found clinical utility in benign hematologic disorders. Therefore, guidelines for diagnosis and treatment of these disorders based on viscoelastic variables have been adapted from the existing transplant, cardiothoracic surgery, and trauma resuscitation literature. As a result, diagnostic and therapeutic strategies for benign hematologic disorders utilizing VETs are not uniform. Accordingly, even though there has been a recent increase in the utilization of VET for the diagnosis and treatment of such disorders, the literature is still in its early stages. Analysis of point-of-care viscoelastic tracings from benign hematologic disorders has the potential to allow prompt recognition of disease and to guide patient-specific intervention. Here we present a review describing the application of VETs to benign hematologic disorders.

Factor XII deficiency in asymptomatic Saudi population: A retrospective cohort study

Factor XII (FXII) deficiency is a rare genetic blood disorder. It can lead to a higher risk of developing deep vein thrombosis or acquired thrombotic disorders than the general population. This retrospective study evaluated patients who opted for surgery and were found to have abnormal clotting profiles and clotting factors on preoperative routine blood. Patients were included regardless of whether they were symptomatic or asymptomatic. The cohort comprised 115 patients with a mean FXII level of 128.04 ± 36.93%. Two (1.79%) patients, both of whom were women, had FXII levels <60%. The mean FXII level was 58 ± 1.41 (range, 57–59%) in this group. The present study shows the prevalence of FXII in the asymptomatic Saudi population. The results provide the normal range for FXII. The findings of our study provide the basis for diagnosing F XII deficiency in the asymptomatic Saudi population.