Thromboelastogram as a Tool to Predict Hypercoagulability in Children With Cystic Fibrosis

Pathophysiology of Cystic Fibrosis Liver Disease

Hepatobiliary complications of Cystic Fibrosis (CF) constitute a significant burden for persons with CF of all ages, with advanced CF liver disease in particular representing a leading cause of mortality. The causes of the heterogeneity of clinical manifestations, ranging from steatosis to focal biliary cholestasis and biliary strictures, are poorly understood and likely reflect a variety of environmental and disease-modifying factors in the setting of underlying CFTR mutations. This review summarizes the current understanding of the pathophysiology of hepatobiliary manifestations of CF, and discusses emerging disease models and therapeutic approaches that hold promise to impact this important yet incompletely addressed aspect of CF care.

Serial rotational thromboelastography (ROTEM) in mechanically ventilated patients with COVID-19 demonstrates hypercoagulopathy despite therapeutic heparinization

Background

Clinical hypercoagulopathy in patients with COVID-19 has been anecdotally described, but there is lack of evidence due to the novelty of this disease. Our study reports the results of rotational thromboelastography (ROTEM) in relation to traditional laboratory coagulation tests and acute phase markers among a cohort of severely ill, mechanically ventilated patients with COVID-19.

Methods

Patients with COVID-19 (N=21) with respiratory failure requiring mechanical ventilation were included in this prospective case series. ROTEM was serially obtained for all patients on three different days during their intensive care unit (ICU) stay and analyzed using repeated measures analysis. Demographic variables, symptoms at the time of presentation, ROTEM values, laboratory values for traditionally measured coagulation profiles, and acute phase reactants were analyzed, in addition to the use of anticoagulation and clinical hypercoagulopathic complications.

Results

The average age of our cohort was 57.9 years old (SD=14.4) and 76.2% were male. The mortality rate was 14.3% (3 of 21). Two patients (12.5%) were identified to have new-onset deep vein thrombosis, two patients (12.5%) were found to have ≥3 episodes of central venous catheter thrombosis, and three patients (18.7%) had confirmed stroke. ROTEM demonstrated elevated EXTEM and INTEM clotting times, including elevated FIBTEM maximum clot firmness (MCF_FIB). All patients treated with therapeutic anticoagulation still demonstrated hypercoagulopathy within the MCF_FIB tests.

Discussion

Repeated measure ROTEMs were able to detect hypercoagulopathy in ICU patients with COVID-19 despite therapeutic anticoagulation with heparin.

Level of evidence

III.

The Effect of Immunosuppression on Coagulation After Liver Transplantation

Everolimus (EVR) is a mammalian target of rapamycin (mTOR) inhibitor commonly used for immunosuppression (IS) after liver transplantation (LT). However, there are concerns about whether mTOR inhibitors may move the hemostatic balance toward a higher likelihood of thrombosis. The present study aimed to investigate potential coagulation disorders after the administration of EVR. We evaluated 54 patients after conversion to an EVR-based IS regimen (n = 26) and compared those patients with patients who were switched to extended-release tacrolimus (TAC) but had never received EVR (n = 28). At baseline and again at 1 month and 6 months after conversion, we measured international normalized ratio, activated partial thromboplastin time, and anticoagulation and fibrinolysis factors, and we performed rotational thromboelastometry (ROTEM). Data were analyzed with a Mann-Whitney U test, a repeated-measure analysis of variance, and a Fisher's exact test. Statistical significance was set at the level of P ≤ 0.05. Plasma levels of von Willebrand factor, fibrinogen, and factor VIII were significantly higher than baseline levels at 1 month and 6 months after conversion of IS to EVR (P < 0.001); plasma levels of protein C, protein S, and plasminogen also increased significantly (P < 0.001). ROTEM confirmed a significant increase in maximum clot firmness in EXTEM, INTEM, and FIBTEM assays (P < 0.001). In all assays, maximum lysis was significantly lower than baseline levels at 1 month and 6 months after conversion to EVR. Patients converted to IS with extended-release TAC exhibited no significant changes in coagulation variables. Retrospective analysis showed a significantly higher incidence of thromboembolic complications among patients treated with EVR-based IS than among those treated with extended-release TAC (P < 0.01). In conclusion, the administration of EVR after LT seems to modify hemostasis to a procoagulant state. Thrombophilia screening before conversion may determine which patients will benefit from conversion to EVR-based IS.

Perioperative Thromboelastometry for Adult Living Donor Liver Transplant Recipients with a Tendency to Hypercoagulability: A Prospective Observational Cohort Study

Background

Hypercoagulability can lead to serious thromboembolic events. The aim of this study was to assess the perioperative coagulation status in liver transplant recipients with a tendency to hypercoagulability.

Methods

In a prospective observational study (South African Cochrane Registry 201405000814129), 151 potential liver transplant recipients were screened for thrombophilic factors from October 2014 to June 2017, and 57 potential recipients fulfilled the inclusion criterion of presenting two or more of the following thrombophilic factors: low protein C, low protein S, low anti-thrombin, increased homocystein, increased antiphospholipid IgG/IgM antibodies, increased lupus anticoagulant, and positive Factor V Leiden mutation. Seven patients were excluded from the study because they fulfilled the exclusion criteria of cancelling the liver transplantation, oral anticoagulation, or intraoperative treatment with rFVIIa. Accordingly, 50 patients were included in the final analysis. Thromboelastometry (ROTEM) (EXTEM, INTEM and FIBTEM) and conventional coagulation tests (CCT) were performed preoperatively, during the anhepatic phase, post reperfusion, and on postoperative days (POD) 1, 3 and 7. ROTEM was used to guide blood product transfusion. Heparin was infused (60-180 U/kg/day) postoperatively for 3 days and then was replaced by low-molecular-weight heparin (20 mg/12 h).

Results

FIBTEM MCF significantly increased postoperatively above reference range on POD 7 despite normal fibrinogen plasma concentrations (p < 0.05). Both EXTEM and INTEM demonstrated significant changes with the phases of transplantation (p < 0.05), but with no intra- or postoperative hypercoagulability observed. INTEM CT (reference range, 100-240 s) normalized on POD 3 and 7 (196.1 ± 69.0 and 182.7 ± 63.8 s, respectively), despite prolonged aPTT (59.7 ± 18.7 and 46.4 ± 15.7 s, respectively; reference range, 20-40 s). Hepatic artery thrombosis (HAT) and portal vein thrombosis (PVT) were reported in 12.0% and 2.0%, respectively, mainly after critical care discharge and with high FIBTEM MCF values in 57% on POD 3 and 86% on POD 7. Receiver operating characteristics curve analyses of FIBTEM MCF were significant predictors for thromboembolic events with optimum cut-off, area under the curve and standard error on POD 3 (>23 mm, 0.779 and 0.097; p = 0.004) and POD 7 (>28 mm, 0.706 and 0.089; p = 0.020). Red blood cells (mean ± SD, 8.68 ± 5.81 units) were transfused in 76%, fresh frozen plasma (8.26 ± 4.14 units) in 62%, and cryoprecipitate (12.0 ± 3.68 units) in 28% of recipients. None of the recipients received intraoperative platelet transfusion or any postoperative transfusion. Main transplant indication was hepatitis C infection in 82%. 76% of recipients included in this highly selected patient population showed increased lupus anticoagulant, 2% increased antiphospholipid IgG/IgM antibodies, 20% increased homocysteine, 74% decreased anti-thrombin, 78% decreased protein C, 34% decreased protein S, and 24% a positive Factor V Leiden mutation. Overall 1-year survival was 62%.

Conclusion

A significant postoperative step-wise increase in FIBTEM MCF beyond the reference range was observed despite normal fibrinogen plasma concentrations, and FIBTEM MCF was a predictor for thromboembolic events in this study population, particularly after POD 3 and 7 on surgical wards when CCTs failed to detect this condition. However, the predictive value of FIBTEM MCF for postoperative HAT and PVT needs to be confirmed in a larger patient population. A ROTEM-guided anticoagulation regime needs to be developed and investigated in future studies.

Perioperative Thromboelastometry for Adult Living Donor Liver Transplant Recipients with a Tendency to Hypercoagulability: A Prospective Observational Cohort Study

Background

Hypercoagulability can lead to serious thromboembolic events. The aim of this study was to assess the perioperative coagulation status in liver transplant recipients with a tendency to hypercoagulability.

Methods

In a prospective observational study (South African Cochrane Registry 201405000814129), 151 potential liver transplant recipients were screened for thrombophilic factors from October 2014 to June 2017, and 57 potential recipients fulfilled the inclusion criterion of presenting two or more of the following thrombophilic factors: low protein C, low protein S, low anti-thrombin, increased homocystein, increased antiphospholipid IgG/IgM antibodies, increased lupus anticoagulant, and positive Factor V Leiden mutation. Seven patients were excluded from the study because they fulfilled the exclusion criteria of cancelling the liver transplantation, oral anticoagulation, or intraoperative treatment with rFVIIa. Accordingly, 50 patients were included in the final analysis. Thromboelastometry (ROTEM) (EXTEM, INTEM and FIBTEM) and conventional coagulation tests (CCT) were performed preoperatively, during the anhepatic phase, post reperfusion, and on postoperative days (POD) 1, 3 and 7. ROTEM was used to guide blood product transfusion. Heparin was infused (60-180 U/kg/day) postoperatively for 3 days and then was replaced by low-molecular-weight heparin (20 mg/12 h).

Results

FIBTEM MCF significantly increased postoperatively above reference range on POD 7 despite normal fibrinogen plasma concentrations (p < 0.05). Both EXTEM and INTEM demonstrated significant changes with the phases of transplantation (p < 0.05), but with no intra- or postoperative hypercoagulability observed. INTEM CT (reference range, 100-240 s) normalized on POD 3 and 7 (196.1 ± 69.0 and 182.7 ± 63.8 s, respectively), despite prolonged aPTT (59.7 ± 18.7 and 46.4 ± 15.7 s, respectively; reference range, 20-40 s). Hepatic artery thrombosis (HAT) and portal vein thrombosis (PVT) were reported in 12.0% and 2.0%, respectively, mainly after critical care discharge and with high FIBTEM MCF values in 57% on POD 3 and 86% on POD 7. Receiver operating characteristics curve analyses of FIBTEM MCF were significant predictors for thromboembolic events with optimum cut-off, area under the curve and standard error on POD 3 (>23 mm, 0.779 and 0.097; p = 0.004) and POD 7 (>28 mm, 0.706 and 0.089; p = 0.020). Red blood cells (mean ± SD, 8.68 ± 5.81 units) were transfused in 76%, fresh frozen plasma (8.26 ± 4.14 units) in 62%, and cryoprecipitate (12.0 ± 3.68 units) in 28% of recipients. None of the recipients received intraoperative platelet transfusion or any postoperative transfusion. Main transplant indication was hepatitis C infection in 82%. 76% of recipients included in this highly selected patient population showed increased lupus anticoagulant, 2% increased antiphospholipid IgG/IgM antibodies, 20% increased homocysteine, 74% decreased anti-thrombin, 78% decreased protein C, 34% decreased protein S, and 24% a positive Factor V Leiden mutation. Overall 1-year survival was 62%.

Conclusion

A significant postoperative step-wise increase in FIBTEM MCF beyond the reference range was observed despite normal fibrinogen plasma concentrations, and FIBTEM MCF was a predictor for thromboembolic events in this study population, particularly after POD 3 and 7 on surgical wards when CCTs failed to detect this condition. However, the predictive value of FIBTEM MCF for postoperative HAT and PVT needs to be confirmed in a larger patient population. A ROTEM-guided anticoagulation regime needs to be developed and investigated in future studies.