Hypercoagulability detected by whole blood thromboelastometry (ROTEM®) and impedance aggregometry (MULTIPLATE®) in obese patients

Do interleukin-17 and interleukin-23 inhibitors alter the coagulation parameters in psoriasis patients?: A retrospective study

Psoriasis is a chronic inflammatory skin condition associated with systemic inflammation and a higher risk of cardiovascular comorbidities. This study retrospectively evaluates coagulation parameters in psoriasis vulgaris patients treated with IL-17 inhibitors (secukinumab, ixekizumab) and IL-23 inhibitors (risankizumab, guselkumab), compared to those untreated systemically. The study reviewed records from 177 patients treated between January 2019 and March 2023. Patients were grouped into control (n = 77), secukinumab (n = 36), ixekizumab (n = 19), guselkumab (n = 24), and risankizumab (n = 21). Coagulation parameters, including PT, aPTT, PLT, MPV, INR, fibrinogen, D-dimer, and B12 levels, were analyzed. The primary endpoint was the comparison of coagulation parameters between groups. Significant differences were found in PT, with secukinumab-treated patients showing a significantly shorter PT compared to controls (p = 0.002). No significant differences were observed in other coagulation parameters across the groups. The study highlights a potential effect of secukinumab on coagulation pathways, possibly related to IL-17's role in inflammation and endothelial function. Despite current literature suggest a risk of cerebrovascular events with risankizumab, this study did not show any significant changes in coagulation parameters with risankizumab, indicating no hypercoagulability risk associated with this IL-23 inhibitor. Our findings suggest IL-17 and IL-23 inhibitors are generally safe concerning coagulation parameters, but regular monitoring may be warranted for patients on secukinumab due to its effect on PT. Further long-term studies are needed to fully understand the cardiovascular risks associated with these therapies.

Cryptogenic ischemic stroke in cardiac transthyretin amyloidosis and sinus rhythm: a case report

Cardiac amyloidosis is a group of diseases characterized by the deposition of amyloid fibers in cardiac tissue. Two forms are mainly reported: light chain (AL) and transthyretin (ATTR) amyloidosis. Among the complications of transthyretin amyloidosis there are thrombotic events and, to a lesser extent, hemorrhagic events. The latter are likely caused by perivascular amyloid deposition resulting in capillary fragility, in addition to INR lability during anticoagulant therapy. The onset of thrombotic events may be caused by the high prevalence of atrial fibrillation (AF), mechanical cardiac dysfunction and atrial myopathy observed in patients with transthyretin amyloidosis. It remains unclear why thromboembolic events occur even in patients with sinus rhythm or adequate anticoagulation, though a hypercoagulable state or underlying inflammation may be involved. We report a case of cryptogenic ischemic stroke in an 86-year-old woman with transthyretin amyloidosis and sinus rhythm. Traditional coagulation tests, whole blood rotational thromboelastometry and impedance aggregometry did not show a hypercoagulable state. The thrombin generation assay did not reveal a prothrombotic state. However, the study of extracellular vesicles highlighted underlying immune-mediated endothelial damage likely responsible for the thrombotic diathesis. It could be hypothesized that inflammation plays a role in the hypercoagulability of patients with transthyretin amyloidosis. Larger prospective studies are needed to validate our hypothesis.

Adiposity and Coagulation: Predicting Postinjury Coagulation With Advanced Imaging Analysis

INTRODUCTION

Anatomic distribution of adipose tissue has demonstrated variable associations with hypercoagulability. Utilizing a retrospective analysis of a previously enrolled prospective cohort, we assessed computed tomography (CT) scan-based anthropometric and volumetric measures of adiposity as predictors of postinjury hypercoagulability.

METHODS

Segmentation analysis of arrival CT scans in significantly injured patients at a single level-I trauma center enrolled from December 2017 to August 2021 were analyzed for anthropometric indices of waist circumference (WC) and sagittal abdominal diameter (SAD), and volumetric parameters of visceral adipose tissue, superficial/deep subcutaneous adipose tissue, psoas/paravertebral muscle volume, and abdominal wall muscle volume. Associations with thromboelastography (TEG) were explored.

RESULTS

Data from 91 patients showed strong correlations between body mass index and standard anthropometric measures of WC and SAD (P < 0.001); calculated volumes of subcutaneous adipose tissue and visceral adipose tissue (P < 0.001); and ratios of subcutaneous adipose:psoas muscle (SP ratio) and visceral adipose:psoas muscle ratio (both with P < 0.001, respectively). Correlation between TEG maximal amplitude (MA) and body mass index and SAD were not significant, with only weak correlation between TEG-MA and WC (r = 0.238, P = 0.041). Moderate but significant correlations existed between SP ratio and TEG-MA (r = 0.340, P = 0.005), but not visceral adipose:psoas muscle ratio (r = 0.159, P = 0.198). The relationship between TEG-MA and SP ratio remained significant when adjusted for injury severity score and lactate level (b = 0.302, P = 0.001).

CONCLUSIONS

SP ratio is more strongly correlated with TEG-MA than standard obesity measures, and independently predicts increasing clot strength/stability after injury. Coagulation-relevant measures of sarcopenic obesity can be measured on CT scan, and may be used to optimize thromboprophylaxis strategies for obese injured patients.

Being Overweight or Obese Is Associated with an Increased Platelet Reactivity Despite Dual Antiplatelet Therapy with Aspirin and Clopidogrel

PURPOSE

Obese patients exhibit an overall increased platelet reactivity and a reduced sensitivity to antiplatelet therapy. The aim of this study is to evaluate the platelet reactivity measured by impedance aggregometry in overweight and obese patients and chronic coronary syndrome (CCS) that were treated with dual antiplatelet therapy (DAPT).

METHODS

Platelet aggregation was assessed by impedance aggregometry in patients with CCS receiving DAPT (aspirin plus clopidogrel). We compared the platelet reactivity in patients with a normal weight versus overweight or obese patients. Furthermore, the correlation between the body mass index (BMI) and adenosine diphosphate- (ADP-) or thrombin receptor-activating peptide- (TRAP-) dependent platelet aggregation was analyzed.

RESULTS

64 patients were included in the study of which 35.9% were patients with normal weight. A higher ADP- and TRAP-dependent platelet reactivity was observed in overweight and obese patients (ADP: median 27 units (U) [IQR 13-39.5] vs. 7 U [6-15], p < 0.001 and TRAP: 97 U [73-118.5] vs. 85 U [36-103], p = 0.035). Significant positive correlations were observed between agonist-induced platelet reactivity and BMI.

CONCLUSION

Despite the use of DAPT, a higher platelet reactivity was found in overweight and obese patients with CCS. If these patients will benefit from treatment with more potent platelet inhibitors, it needs to be evaluated in future clinical trials.

Association Between Thromboelastometry Identified Hypercoagulability and Thromboembolic Complications After Arthroplasty: A Prospective Observational Study in Patients With Obesity

The prothrombotic state of obesity can increase the risk of thromboembolism. We aimed to investigate if there was an association between baseline hypercoagulable rotational thromboelastometry (ROTEM) profile and thromboembolic complications in arthroplasty patients with obesity. Patients with a body mass index ≥ 25 kg/m2 and/or waist circumference ≥94 cm (M) and 80 cm (F) undergoing hip and knee arthroplasty had pre- and postoperative ROTEM. ROTEM values were compared by outcome status using an independent sample equal-variance t-test. Of the 303 total participants, hypercoagulability defined as extrinsically activated thromboelastometry maximum clot firmness G score ≥ 11 K dyne/cm2, was observed in 90 (30%) of the 300 participants with preoperative ROTEM assays. Clinically significant thromboembolic complications occurred in 5 (1.7%) study participants before discharge and in 10 (3.3%) by 90 days. These included 6 with pulmonary emboli, 3 with deep venous thrombus, and 1 with myocardial infarction. We found no evidence for an association between baseline hypercoagulability and incident thromboembolic events, analysis limited by the number of events. Postoperative decrease in platelets and an increase in fibrinogen were observed. ROTEM parameter changes differed across obesity categories.

Investigation of differences in coagulation characteristics between hospitalized patients with SARS-CoV-2 Alpha, Delta, and Omicron variant infection using rotational thromboelastometry (ROTEM): A single-center, retrospective, observational study

BACKGROUND

The severe acute respiratory syndrome coronavirus 2 Omicron variant has a low rate of serious illness, is highly contagious, and has spread rapidly since January 2022. The number of severe cases and deaths remains problematic. Here, we aimed to elucidate the coagulation pathology of Omicron-infected patients using rotational thromboelastometry.

METHODS

Patients with coronavirus disease 2019, hospitalized and treated from January 2021 to April 2022, were included. The Alpha-Delta and Omicron groups were defined during admission. Blood tests, clinical course, and rotational thromboelastometry measurements were compared using a propensity score-matched cohort.

RESULTS

Both groups had 21 patients each. Lactate dehydrogenase (Alpha-Delta group [interquartile range] vs. Omicron group [interquartile range]; 449 [368-518] U/L vs. 241 [196-398] U/L, p = 0.01) and ferritin (1428 [1145-3061] ng/dl vs. 481 [188-881] ng/dl, p = 0.0002) levels were significantly lower in the Omicron group. In rotational thromboelastometry, the thrombus hardness indexes FIBTEM A5 (29 [23-34] mm vs. 23 [18-28] mm, p = 0.034) and maximum clot firmness (34 [27-40] mm vs. 26 [21-33] mm, p = 0.021) were significantly lower in the Omicron group, whereas the fibrinolysis index FIBTEM LI60 (98 [92-100] % vs. 100 [100-100] %, p = 0.0082) was higher.

CONCLUSION

Severe coagulation abnormalities may be less likely in Omicron-infected patients than in those infected with the previous Alpha and Delta variants.

Translating MSC Therapy in the Age of Obesity

Mesenchymal stromal cell (MSC) therapy has seen increased attention as a possible option to treat a number of inflammatory conditions including COVID-19 acute respiratory distress syndrome (ARDS). As rates of obesity and metabolic disease continue to rise worldwide, increasing proportions of patients treated with MSC therapy will be living with obesity. The obese environment poses critical challenges for immunomodulatory therapies that should be accounted for during development and testing of MSCs. In this review, we look to cancer immunotherapy as a model for the challenges MSCs may face in obese environments. We then outline current evidence that obesity alters MSC immunomodulatory function, drastically modifies the host immune system, and therefore reshapes interactions between MSCs and immune cells. Finally, we argue that obese environments may alter essential features of allogeneic MSCs and offer potential strategies for licensing of MSCs to enhance their efficacy in the obese microenvironment. Our aim is to combine insights from basic research in MSC biology and clinical trials to inform new strategies to ensure MSC therapy is effective for a broad range of patients.

Global hemostatic profiling in patients with decompensated cirrhosis and bacterial infections

Background & Aims

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.

Methods

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).

Results

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.

Conclusion

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.

Lay summary

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.

Preoperative preparation and premedication of bariatric surgical patient

The prevalence of obesity has tripled worldwide over the past four decades. The United States has the highest rates of obesity, with 88% of the population being overweight and 36% obese. The UK has the sixth highest prevalence of obesity. The problem of obesity is not isolated to the developed world and has increasingly become an issue in the developing world as well. Obesity carries an increased risk of many serious diseases and health conditions, including type 2 diabetes, heart disease, stroke, sleep apnea, and certain cancers. Our ability to take care of this population safely throughout the perioperative period begins with a thorough and in-depth preoperative assessment and meticulous preparation. The preoperative assessment begins with being able to identify patients who suffer from obesity by using diagnostic criteria and, furthermore, being able to identify patients whose obesity is causing pathologic and physiologic changes. A detailed and thorough anesthesia assessment should be performed, and the anesthesia plan individualized and tailored to the specific patient's risk factors and comorbidities. The important components of the preoperative anesthesia assessment and patient preparation in the patient suffering from obesity include history and physical examination, airway assessment, medical comorbidities evaluation, functional status determination, risk assessment, preoperative testing, current weight loss medication, and review of any prior weight loss surgeries and their implications on the upcoming anesthetic. The preoperative evaluation of this population should occur with sufficient time before the planned operation to allow for modifications of the preoperative management without needing to delay surgery as the perioperative management of patients suffering from obesity presents significant practical and organizational challenges.

Thromboelastography in obese horses with insulin dysregulation compared to healthy controls

BACKGROUND

Both obesity and metabolic syndrome are associated with hypercoagulability in people, increasing the risk of cardiovascular disease and thromboembolic events. Whether hypercoagulability exists in obese, insulin-dysregulated horses is unknown.

HYPOTHESIS/OBJECTIVES

To determine if coagulation profiles differ between healthy horses and those with obesity and insulin dysregulation.

ANIMALS

Fifteen healthy horses (CON) and 15 obese, insulin-dysregulated horses (OBID). Individuals were university or client owned.

METHODS

Case-control study. Obesity was defined as a body condition score (BCS) ≥7.5/9 (modified Henneke scale). Insulin dysregulation status was assessed by an oral sugar test (OST). Kaolin-thromboelastography and traditional coagulation variables were compared between groups. The direction and strength of the association between coagulation variables and BCS and OST results were determined using Spearman's correlation.

RESULTS

Thromboelastography variables MA (OBID: 69.5 ± 4.5 mm; CON: 64.8 ± 4.3 mm; P = .007) and G-value (OBID: 11749 ± 2536 dyn/m2 ; CON: 9319 ± 1650 dyn/m2 ; P = .004) were higher in OBID compared to CON. Positive correlations between MA and BCS (R = 0.45, P = .01) and serum insulin (T0 : R = 0.45, P = .01; T60 : R = 0.39, P = .03), and G-value and BCS (R = 0.46, P = .01), and serum insulin (T0 : R = 0.48, P = .007; T60 : R = 0.43, P = .02; T90 : R = 0.38, P = .04) were present.

CONCLUSIONS AND CLINICAL IMPORTANCE

Obese, insulin-dysregulated horses are hypercoagulable compared to healthy controls.

Risk Factors of Venous Thromboembolism in Noncritically Ill Patients Hospitalized for Acute COVID-19 Pneumonia Receiving Prophylactic-Dose Anticoagulation

Background: Therapeutic/intermediate-dose heparin reduces the risk of thromboembolic events but increases the risk of major bleeding in patients hospitalized for acute COVID-19 pneumonia. Objectives: To prospectively assess the incidence of objectively proven venous thromboembolism (VTE) and identify predisposing risk factors in a cohort of hospitalized patients with acute COVID-19 pneumonia undergoing prophylactic-dose heparin. Patients and methods: All consecutive patients admitted for acute COVID-19 pneumonia to the General Internal Medicine Unit of Padova University Hospital, Italy between November 2020 and April 2021, and undergoing prophylactic-dose heparin, were enrolled. Demographic and clinical characteristics and laboratory and radiological findings were recorded on admission. Cases were patients who developed VTE during their hospital stay. Univariable and multivariable logistic regression analyses were used to ascertain the risk factors associated with developing in-hospital VTE. Results: 208 patients (median age: 77 years; M/F 98/110) were included; 37 (18%) developed in-hospital VTE during a median follow-up of 10 days (IQR, 4−18). VTE patients were significantly younger (p = 0.004), more obese (p = 0.002), and had a lower Padua prediction score (p < 0.03) and reduced PaO2/FIO2 ratio (p < 0.03) vs. controls. Radiological findings of bilateral pulmonary infiltrates were significantly more frequent in VTE patients than controls (p = 0.003). Multivariable regression showed that obesity (1.75, 95% CI 1.02−3.36; p = 0.04) and bilateral pulmonary infiltrates on X-rays (2.39, 95% CI 1.22−5.69; p = 0.04) were correlated with increased risk of in-hospital VTE. Conclusions: Obesity and bilateral pulmonary infiltrates on imaging may help clinicians to identify patients admitted to medical wards for acute COVID-19 pneumonia at risk of developing VTE despite prophylactic-dose heparin. Further studies are needed to evaluate whether the administration of therapeutic/intermediate-dose heparin may help prevent VTE episodes without further increasing the bleeding risk.

Rotational thromboelastometry (ROTEM® ) in gestational diabetes mellitus and coagulation in healthy term pregnancy: A prospective observational study in Australia

BACKGROUND

Rotational thromboelastometry (ROTEM^® ) is a point-of-care test of coagulation. ROTEM^® -defined hypercoagulability has been identified in pregnant women and in non-pregnant patients with diabetes mellitus. Pregnancy is known to be a hypercoagulable state, but the influence of gestational diabetes mellitus (GDM) on coagulation is unknown.

AIM

The aim of this study was to assess the combined effect of pregnancy and GDM on coagulation using ROTEM^® and to compare this to healthy pregnant women presenting for elective caesarean delivery.

MATERIALS AND METHODS

Ethics approval was granted for recruitment of women presenting for elective caesarean delivery. Women with pre-existing conditions affecting coagulation were excluded. Group N included health pregnant women at term and Group G included pregnant women at term with GDM. Data regarding GDM management and glycaemic control were collected. Poor glycaemic control was defined by markers of accelerated fetal growth and elevated fasting or postprandial blood glucose levels. The ROTEM^® parameters (extrinsically activated thromboelastometric test (EXTEM) / fibrin polymerisation test (FIBTEM) amplitude at five minutes, coagulation time, maximum clot firmness and clot formation time) were compared between the two groups using Student's t-test.

RESULTS

There were 75 women in Group N and 21 women in Group G. Mean age and median body mass index values were comparable for both groups. There were no statistical differences found between the EXTEM and FIBTEM parameters analysed for the two groups.

CONCLUSIONS

There was no association between GDM and increased hypercoagulability as demonstrated by ROTEM^® parameters in healthy pregnant women presenting for elective caesarean delivery at term.

Impact of cardiovascular burden on coagulation pathway in apparently healthy women planning oocyte donation

BACKGROUND

Hormonal fertility treatments are associated with increased coagulation factors inducing procoagulant milieu and possibly thrombotic risk.

OBJECTIVE

To assess coagulation by ROTEM and coagulation tests in apparently healthy infertile women before oocyte donation procedure.

METHODS

We enrolled 51 women (Assisted Reproductive Technology Centre, Florence). ROTEM and coagulation parameters were assessed before the start of infertility treatment.

RESULTS

We divided women in 3 groups according to the number of cardiovascular risk factors: Group A (n = 10), Group B (n = 16), and Group C (n = 25). By considering ROTEM Extem test, a significantly increased of MCF, TPI, and G were observed in groups B (p = 0.005, p = 0.03, and p = 0.007) and C (p = 0.01, p = 0.05, and p = 0.005) in comparison to group A. As regards ROTEM Intem test, the TPI and G values were significantly higher in groups B and C in comparison to group A (p < 0.01). MCF by Fibtem test significantly increased in groups B and C than in group A (p = 0.004 and p = 0.002, respectively). FVIII, vWF:Ag and D-dimer values significantly increase according to the presence of≥2 risk factors.

CONCLUSIONS

Data from coagulative assessment permit to sensitively identify women with potentially procoagulable state, which represents a risk factor of thromboembolic event during hormone treatment.

Absence of hypercoagulability after nCoV-19 vaccination: An observational pilot study

BACKGROUND

It is still unknown whether COVID-19 vaccines induce a prothrombotic state or increase the hypercoagulable condition in subjects with a predisposition to thrombosis.

OBJECTIVES

We evaluated the coagulation profile in a series of healthy subjects who received the first dose of the BNT162b2 or the ChAdOx1 vaccines and assessed whether hypercoagulability developed.

PATIENTS/METHODS

Volunteers among the staff of the University of Padua or health care professionals in the Padua University Hospital who had received either the ChAdOx1 or BNT162b2 vaccine in the previous 10 ± 2 days were eligible. A cohort of unvaccinated volunteers among family members of the University staff acted as control group. Global coagulation monitoring was assessed by whole blood rotational thromboelastometry, whole blood impedance aggregometry and thrombin generation. Platelet count was also obtained.

RESULTS

One hundred and ninety subjects were enrolled: 101 (53.2%) received the ChAdOx1 vaccine and 89 (46.8%) the BNT162b2 vaccine. Twenty-eight non-vaccinated subjects acted as controls. Thromboelastometry parameters were all comparable among groups. Thrombin receptor activating peptide (TRAP)-, ADP- and ASPI-induced platelet aggregation were similar among groups, as well as platelet count. Endogenous thrombin potential (ETP) was comparable among groups. The results were confirmed after controlling for age, gender and hormonal. Considering women taking combined oral contraceptives or thrombophilia carriers, no differences were detected in thromboelastometry or thrombin generation parameters between subjects who received ChAdOx1 vs. BNT162b2 vaccines.

CONCLUSIONS

No significant activation of fibrinogen-driven coagulation, plasma thrombin generation or clinically meaningful platelet aggregation after ChAdOx1 or BNT162b2 vaccination was observed.

Point of care diagnostic of hypercoagulability and platelet function in COVID-19 induced acute respiratory distress syndrome: a retrospective observational study

Background

Coronavirus disease 2019 (COVID-19) associated coagulopathy (CAC) leads to thromboembolic events in a high number of critically ill COVID-19 patients. However, specific diagnostic or therapeutic algorithms for CAC have not been established. In the current study, we analyzed coagulation abnormalities with point-of-care testing (POCT) and their relation to hemostatic complications in patients suffering from COVID-19 induced Acute Respiratory Distress Syndrome (ARDS). Our hypothesis was that specific diagnostic patterns can be identified in patients with COVID-19 induced ARDS at risk of thromboembolic complications utilizing POCT.

Methods

This is a single-center, retrospective observational study. Longitudinal data from 247 rotational thromboelastometries (Rotem®) and 165 impedance aggregometries (Multiplate®) were analysed in 18 patients consecutively admitted to the ICU with a COVID-19 induced ARDS between March 12th to June 30th, 2020.

Results

Median age was 61 years (IQR: 51–69). Median PaO₂/FiO₂ on admission was 122 mmHg (IQR: 87–189), indicating moderate to severe ARDS. Any form of hemostatic complication occurred in 78 % of the patients with deep vein/arm thrombosis in 39 %, pulmonary embolism in 22 %, and major bleeding in 17 %. In Rotem® elevated A10 and maximum clot firmness (MCF) indicated higher clot strength. The delta between EXTEM A10 minus FIBTEM A10 (ΔA10) > 30 mm, depicting the sole platelet-part of clot firmness, was associated with a higher risk of thromboembolic events (OD: 3.7; 95 %CI 1.3–10.3; p = 0.02). Multiplate® aggregometry showed hypoactive platelet function. There was no correlation between single Rotem® and Multiplate® parameters at intensive care unit (ICU) admission and thromboembolic or bleeding complications.

Conclusions

Rotem® and Multiplate® results indicate hypercoagulability and hypoactive platelet dysfunction in COVID-19 induced ARDS but were all in all poorly related to hemostatic complications..

Weight-adjusted versus fixed dose heparin thromboprophylaxis in hospitalized obese patients: A systematic review and meta-analysis

BACKGROUND

Fixed dose unfractionated or low molecular weight heparin is the recommended treatment for venous thromboembolism (VTE) prevention in hospitalized patients. However, its efficacy has been questioned in obese population. Results of previous studies on weight-adjusted doses of heparin for VTE prevention are contradictory. Different anticoagulant regimens are used in clinical practice, but their role remains to be elucidated.

AIMS

To clarify the efficacy and safety of weight-adjusted dose heparin for VTE prevention in obese subjects hospitalized for medical and surgical conditions.

METHODS

Twelve studies were identified as reporting VTE occurrence, major or minor bleeding and anti-Xa levels. A random-effect meta-analysis was conducted to derive odds ratios (OR) comparing fixed vs weight adjusted-doses heparins on VTE occurrence, bleeding, anti-Xa levels. Medical and surgical patients, prospective vs retrospective and quality of studies were extracted for moderators and meta-regression analysis.

RESULTS

Weight-adjusted dose heparin administration was not associated with reduced VTE occurrence (6320/13317 patients, OR 1.03, 95% C.I. 0.79 to 1.35), nor increased bleeding (5840/10906 patients, OR 0.84, 95% C.I. 0.65 to 1.08), but it was associated with higher anti-Xa levels (284/294 patients, ES 2.04, 95% C.I. 1.16 to 2.92, p<0.0001). A significant heterogeneity was present for comparison of anti-Xa levels (I²=94%, p=0.0001) but not for VTE occurrence or bleeding (I²=7.6% and 12.8% respectivel). None of the moderators explained the heterogeneity of the results among primary studies.

CONCLUSION

Weight-adjusted dose as compared to fixed-dose of heparins in the prevention of VTE in obese patients was not associated with a lower risk of VTE nor a higher risk of bleeding.

Thromboelastography-Based Profiling of Coagulation Status in Patients Undergoing Bariatric Surgery: Analysis of 422 Patients

INTRODUCTION/PURPOSE

Some clinical indicators suggest hypercoagulability/hyperaggregability in patients with morbid obesity. Thromboelastography (TEG®) has been used to profile coagulation status in surgical patients. We aimed to assess coagulation profiles in patients with morbid obesity undergoing bariatric surgery by correlating demographic and patient characteristics to pre-operative TEG® values.

MATERIALS AND METHODS

Pre-operative TEG® values from 422 patients undergoing bariatric surgery were evaluated. TEG® results were analyzed by gender, use of medications known to alter the coagulation profile, and body mass index (BMI).

RESULTS

Patients have a mean of 45.03 ± 11.8 years, female (76.3%), and with a mean BMI of 42 kg/m ¹. The overall coagulation profile of female patients was significantly different from males, even in the sub-cohort without use of medications known to alter coagulation. The majority of patients (94%) with a G value > 15 dynes/cm ¹ (clot strength) were female. In females, there was no association between BMI and TEG® values; however, in men, there was a statistically significant difference in TEG® values for those with BMI < 40 kg/m ¹ compared to those with BMI > 50 kg/m².

CONCLUSIONS

TEG®-based analysis of coagulation profiles offers unique insights. Compared to laboratory normal values (R time, angle, maximal amplitude, and G values), patients with morbid obesity may have a tendency for hypercoagulability/hyperaggregability, with mean values at the higher limit. A significant hypercoagulable difference in TEG® values was identified in female as compared to male patients. Male patients with a BMI greater than 50 kg/m² were also found to be increasingly hypercoagulable.

Influence of Hepatocellular Carcinoma on Platelet Aggregation in Cirrhosis

Simple Summary

Platelets are blood cells, the main function of which is to form clots and prevent/stop bleeding. However, it has been shown that platelets may be involved in additional pathophysiological processes, including stimulation of cancer growth and metastasis. In fact, inhibition of platelets in patients with various types of cancer has resulted in lower risks of cancer progression and death. This possibility has not yet been considered in patients with cirrhosis (chronic liver disease) and hepatocellular carcinoma (the most common type of liver cancer) because their platelet function has never been investigated. In this study, we show that hepatocellular carcinoma in patients with cirrhosis is associated with significantly altered (increased) platelet function. This paves the way for further studies to evaluate whether the inhibition of these hyper-functional platelets could be beneficial in patients with cirrhosis and hepatocellular carcinoma.

Abstract

Hyper-functional platelets are being proposed as a potential therapeutic target in multiple cancers. Whether this can be considered in patients with cirrhosis and hepatocellular carcinoma (HCC) is unknown as their platelet function has not yet been investigated. We evaluated platelet function in cirrhosis patients with HCC. Patients with cirrhosis with and without HCC were prospectively recruited. Platelet aggregation, a marker of platelet function, was assessed by impedance aggregometry with adenosine diphosphate (ADP), arachidonic acid (ASPI), and thrombin (TRAP) stimulation. Plasmatic levels of Von Willebrand factor antigen (VWF) were also determined. One-hundred patients were recruited (50 cirrhotics with and 50 without HCC). Cirrhosis severity by Child class and platelet count were comparable between cirrhotics with and without HCC. Cirrhotics with HCC had higher ADP- (45 vs. 28; p < 0.001), ASPI- (47 vs. 28; p < 0.001), and TRAP- (85 vs. 75; p = 0.01) induced platelet aggregation than cirrhotics without HCC, all indicative of platelet hyper-function. The relatively increased platelet aggregation in patients with HCC was confirmed after adjusting the analysis for platelet count/severity of thrombocytopenia. Levels of VWF were higher in patients with vs. without HCC (348 vs. 267; p = 0.006), particularly in compensated cirrhosis. In patients with cirrhosis, HCC is associated with increased platelet aggregation and higher VWF. The clinical implications of these findings deserve further investigation.

Platelet hyperaggregability and venous thrombosis risk: results from the RETROVE project

The aim of the study was to determine whether platelet hyperaggregability correlates with short closure times (PFA-100) and if hyperaggregability is associated with the risk of venous thrombosis in a Spanish population. Case--control study (RETROVE project) involving 400 patients with venous thrombosis and 400 healthy controls. We determined platelet aggregation in platelet-rich plasma (PRP) by light transmission aggregometry. Various concentrations of two aggregation agonists [ADP and epinephrine (EPI)] were tested to determine the percentage of maximal aggregation and the percentage area under the curve (AUC). Venous thrombosis risk associated with platelet hyperaggregability was calculated by logistic regression. We estimated the crude and adjusted (by sex and age) odds ratios (OR) for venous thrombosis risk. An agonist concentration of 0.5 μmol/l differentiated between hypo-responders and hyper-responders at the following AUC cut-off values: EPI: the 50th percentile for aggregation with 0.5 μmol/l of EPI (EPI_AUC) was 22.53% (>22.53% = hyper-EPI); the crude risk for venous thrombosis was statistically significant (OR = 1.37; 95% CI 1.03-1.82); ADP: the 75th percentile for aggregation with 0.5 μmol/l of ADP (ADP_AUC) was 29.6% (>29.6% = hyper-ADP), with a significant crude risk for venous thrombosis (OR = 1.44; 95% CI 1.05-1.98). However, after adjustment for confounders (age), the ORs for EPI or ADP aggregation were no longer significant. EPI_AUC and PFA-100 values with the EPI agonist were significantly correlated (R = -0.342, P < 0.01). Only 12% of the PFA-100 values were explained by platelet aggregation. In this case--control study, platelet hyperaggregability was not associated with the risk of developing venous thrombosis.

Greater Fibrinolysis Resistance but No Greater Platelet Aggregation in Critically Ill COVID-19 Patients

Background:

The hemostatic balance in patients with coronavirus disease 2019 (COVID-19) seems to be shifted toward a hypercoagulable state. The aim of the current study was to assess the associated coagulation alterations by point-of-care-diagnostics, focusing on details of clot formation and lysis in these severely affected patients.

Methods:

The authors’ prospective monocentric observational study included critically ill patients diagnosed with COVID-19. Demographics and biochemical data were recorded. To assess the comprehensive hemostatic profile of this patient population, aggregometric (Multiplate) and viscoelastometric (CloPro) measures were performed in the intensive care unit of a university hospital at a single occasion. Coagulation analysis and assessment of coagulation factors were performed. Data were compared to healthy controls.

Results:

In total, 27 patients (21 male; mean age, 60 yr) were included. Impedance aggregometry displayed no greater platelet aggregability in COVID-19 in comparison with healthy controls (area under the curve [AUC] in adenosine diphosphate test, 68 ± 37 U vs. 91 ± 29 U [−27 (Hodges–Lehmann 95% CI, −48 to −1); P = 0.043]; AUC in arachidonic acid test, 102 ± 54 U vs. 115 ± 26 U [−21 (Hodges–Lehmann 95% CI, −51 to 21); P = 0.374]; AUC in thrombin receptor activating peptide 6 test, 114 ± 61 U vs. 144 ± 31 U [−31 (Hodges–Lehmann 95% CI, −69 to −7); P = 0.113]). Comparing the thromboelastometric results of COVID-19 patients to healthy controls, the authors observed significant differences in maximum clot firmness in fibrin contribution to maximum clot firmness assay (37 ± 11 mm vs. 15 ± 4 mm [21 (Hodges–Lehmann 95% CI, 17 to 26); P < 0.001]) and lysis time in extrinsic activation and activation of fibrinolysis by tissue plasminogen activator assay (530 ± 327 s vs. 211 ± 80 s [238 (Hodges–Lehmann 95% CI, 160 to 326); P < 0.001]).

Conclusions:

Thromboelastometry in COVID-19 patients revealed greater fibrinolysis resistance. The authors did not find a greater platelet aggregability based on impedance aggregometric tests. These findings may contribute to our understanding of the hypercoagulable state of critically ill patients with COVID-19.

Despite increases in von Willebrand factor, platelet aggregability based on impedance aggregometry testing was not increased in critically ill COVID-19, although viscoelastometric testing noted fibrinolysis resistance. These findings contribute to our understanding of the hypercoagulable state of COVID-19 and may have important considerations for management strategies.

More Severe Hypercoagulable State in Acute COVID-19 Pneumonia as Compared With Other Pneumonia

Objective

To conduct a comprehensive evaluation of coagulation profiles—via traditional and whole blood thromboelastometry tests—in coronavirus disease 2019 (COVID-19)–positive vs COVID-19–negative patients admitted to medical wards for acute pneumonia.

Patients and Methods

We enrolled all consecutive patients admitted to internal medicine wards of Padova University Hospital between 7 March and 30 April, 2020, for COVID-19–related pneumonia (cases) vs non–COVID-19 pneumonia (controls). A group of healthy individuals acted as baseline for thromboelastometry parameters.

Results

Fifty-six cases (mean age, 64±15 years; male/female, 37/19) and 56 controls (mean age, 76±11 years; male/female, 35/21) were enrolled. Cases and controls exhibited markedly hypercoagulable thromboelastometry profiles vs healthy individuals, mainly characterized by a significantly shorter propagation phase of coagulation (clot formation time) and significantly increased maximum clot firmness (P<.001 for all comparisons). Patients with COVID-19 pneumonia had significantly shorter clot formation time and higher maximum clot firmness (P<.01 and P<.05, respectively, for all comparisons) than did controls.

Conclusion

Patients admitted to internal medicine wards for COVID-19 pneumonia presented a markedly prothrombotic state, which seems peculiar to COVID-19 rather than pneumonia itself.

Rotational thromboelastometry to assess hypercoagulability in COVID-19 patients

•

COVID-19 is associated with a high incidence of thromboembolic complications.

•

ROTEM® analysis confirmed the hypercoagulable state of COVID-19 patients admitted to the ICU.

•

ROTEM® had no additional value to identify COVID-19 patients at risk of developing thromboembolic complications.

The haemostatic system in acromegaly: a single-centre case-control study

PURPOSE

Although the mortality from acromegaly is due in most cases to an increased cardiovascular risk, no study has globally evaluated the haemostatic balance in acromegaly to ascertain the presence of hypercoagulability. We endeavoured to assess the overall coagulation profile in patients with acromegaly using both traditional and global coagulation assays.

METHODS

Consecutive outpatients with a diagnosis of acromegaly were enrolled and matched with healthy subjects. Whole blood thromboelastometry and impedance aggregometry, procoagulant, anticoagulant and fibrinolytic factors, as well as thrombin-generation assay and circulating endothelium-derived microvesicles were measured.

RESULTS

Forty patients (M/F 14/26, median age 59 years) with either new diagnosis (naïve, 14 cases) or treated acromegaly (26 cases) were enrolled in this study. Median time from diagnosis was 11 years. Levels of factor VIII and fibrinogen were significantly higher in acromegalic patients vs. controls (p = 0.029 and < 0.003, respectively). Overall, thromboelastometry parameters showed a faster coagulation formation with a more stable clot. Acromegaly patients showed significantly higher endogenous thrombin potential [ETP] and thrombin peak compared to controls (p = 0.016 and p < 0.001, respectively). ETP remained significantly higher (p < 0.001) when thrombomodulin was added. Endothelial-derived microvesicles were significantly higher in acromegaly patients than controls (52 [40.5-67] MVs/µL and 30 [18-80] MVs/µL, p = 0.03). Patients with untreated (naïve) acromegaly showed significantly reduced ETP with and without thrombomodulin vs. patients with treated acromegaly (p = 0.01).

CONCLUSION

Hypercoagulability in acromegaly is mainly due to higher levels of fibrinogen, factor VIII and thrombin generation, and appears to be more linked to the chronic phase of the disease.

Hypercoagulability of COVID-19 patients in intensive care unit: A report of thromboelastography findings and other parameters of hemostasis

BACKGROUND

The severe inflammatory state secondary to COVID-19 leads to a severe derangement of hemostasis that has been recently described as a state of disseminated intravascular coagulation (DIC) and consumption coagulopathy, defined as decreased platelet count, increased fibrin(ogen) degradation products such as D-dimer, as well as low fibrinogen.

AIMS

Whole blood from 24 patients admitted at the intensive care unit because of COVID-19 was collected and evaluated with thromboelastography by the TEG point-of-care device on a single occasion and six underwent repeated measurements on two consecutive days for a total of 30 observations. Plasma was evaluated for the other parameters of hemostasis.

RESULTS

TEG parameters are consistent with a state of hypercoagulability as shown by decreased values, and increased values of K angle and MA. Platelet count was normal or increased, prothrombin time and activated partial thromboplastin time were near(normal). Fibrinogen was increased and D-dimer was dramatically increased. C-reactive protein was increased. Factor VIII and von Willebrand factor (n = 11) were increased. Antithrombin (n = 11) was marginally decreased and protein C (n = 11) was increased.

CONCLUSION

The results of this cohort of patients with COVID-19 are not consistent with acute DIC, rather they support hypercoagulability together with a severe inflammatory state. These findings may explain the events of venous thromboembolism observed in some of these patients and support antithrombotic prophylaxis/treatment. Clinical trials are urgently needed to establish the type of drug, dosage, and optimal duration of prophylaxis.

Endothelial Damage of the Portal Vein is Associated with Heparin-Like Effect in Advanced Stages of Cirrhosis

Background Portal vein thrombosis (PVT) is the most common thrombotic complication in cirrhosis; however, local risk factors involved in its pathogenesis are still not fully investigated. The aim of the study was to evaluate hemostasis and endothelial damage in the portal vein in patients with cirrhosis and portal hypertension.

Methods Adult cirrhotics undergoing transjugular intrahepatic portosystemic shunt were consecutively enrolled. Rotational thromboelastometry (ROTEM), dosage of total circulating glycosaminoglycans (GAGs), and endotoxemia levels (lipopolysaccharide [LPS]), along with evaluation of endothelial dysfunction by quantification of circulating endothelial microparticles (MPs), were performed on citrated peripheric and portal venous blood samples from each enrolled patient.

Results Forty-five cirrhotics were enrolled. ROTEM analysis revealed the presence of a significant heparin-like effect in portal blood (median ɑ angle NATEM 50° vs. HEPTEM 55°, p = 0.027; median coagulation time NATEM 665 s vs. HEPTEM 585 s, p = 0.006), which was not detected in peripheral blood, and was associated with a higher concentration of circulating GAGs. Even though total annexin V-MP circulating MPs were less concentrated in the splanchnic district, the proportion of MPs of endothelial origin, with respect to annexin V-MP, was significantly increased in the portal district (p = 0.036). LPS concentration was higher in portal (197 pg/mL) compared with peripheral blood (165 pg/mL) (p < 0.001).

Conclusion Evidences of a damage of glycocalyx along with increased concentration of endothelial MPs suggest the presence of a significant endothelial alteration in the portal vein with respect to peripheral veins. Portal site-specific endothelial damage could hamper its antithrombotic properties and may represent an important local risk factor in the pathogenesis of PVT.

Relationship of Body Adiposity with Platelet Function in Obese and Non-obese Individuals

Background

Adiposity is firmly linked to a higher incidence of various cardiovascular and metabolic morbidities, including diabetes, hypertension, and thromboembolism. This research study was aimed to verify the association of increased adiposity and hyperreactivity of platelets in obese and non-obese individuals.

Methods

This cross-sectional study was conducted on 42 subjects aged 18 years and above. Subjects were divided into obese and non-obese groups based on their body mass index (BMI). The data was collected through self-administered questionnaires. All participants underwent body composition analysis. Blood samples were collected from all subjects and taken to the Pharmacology Department for the preparation of platelet-rich plasma (PRP) and poor platelet plasma (PPP). Platelet aggregation was induced by arachidonic acid and was monitored with a Bio/Data multichannel aggregation profiler (Bio/Data Corp., Horsham, PA, USA).

Results

Significant differences were observed in most parameters, such as fat mass, body fat percentage, free fat mass (FFM), the percentage of trunk fat, total body water, waist-hip ratio (WHR), and basal metabolic rate (BMR) of obese and non-obese subjects. The average percent of platelet aggregation in obese and non-obese subjects was 56.33 ± 15.62 and 59.38 ± 12.62, respectively. The average area under the curve (AUC) for platelet aggregation for both groups was 339.33 ± 191.55 and 342 ± 146.68, respectively. Platelet function was not significantly different and didn’t positively correlate with most parameters of the body composition, except WHR, which positively correlated with AUC for platelet function. 

Conclusion

There was no significant direct correlation between adiposity and platelet activation in obese subjects. However, a significant positive correlation of AUC for platelet aggregation with WHR was observed (resistance (r)-value: 0.307, p < 0.05). These findings suggest that WHR could be an effective determinant to assess the risk of thromboembolism in obese individuals.

Increased Cardiovascular Risk Associated with Chemical Sensitivity to Perfluoro-Octanoic Acid: Role of Impaired Platelet Aggregation

Perfluoro–alkyl substances (PFAS), particularly perfluoro–octanoic acid (PFOA), are persisting environmental chemicals showing bioaccumulation in human tissues. Recently, exposure to PFAS has been associated with increased prevalence of cardiovascular diseases (CVDs). However, a causal role of PFAS in atherosclerosis pathogenesis is under-investigated. Here, we investigated the effect of PFOA exposure on platelets’ function, a key player in atherosclerosis process. PFOA accumulation in platelets was evaluated by liquid chromatography-mass spectrometry. Changes in platelets’ membrane fluidity and activation after dose-dependent exposure to PFOA were evaluated by merocyanine 540 (MC540) and anti P-Selectin immune staining at flow cytometry, respectively. Intracellular calcium trafficking was analyzed with Fluo4M probe, time-lapse live imaging. Platelets’ aggregation state was also evaluated with Multiplate^® aggregometry analyzer in 48 male subjects living in a specific area of the Veneto region with high PFAS environmental pollution, and compared with 30 low-exposure control subjects. Platelets’ membrane was the major target of PFOA, whose dose-dependent accumulation was associated in turn with increased membrane fluidity, as expected by a computational model; increased activation at resting condition; and both calcium uptake and aggregation upon activation. Finally, exposed subjects had higher serum and platelets levels of PFOA, together with increased aggregation parameters at Multiplate^®, compared with controls. These data help to explain the emerging association between PFAS exposure and CVD.

Perioperative care of the obese patient

Background

Obesity has become an increasing problem worldwide during the past few decades. Hence, surgeons and anaesthetists will care for an increasing number of obese patients in the foreseeable future, and should be prepared to provide optimal management for these individuals. This review provides an update of recent evidence regarding perioperative strategies for obese patients.

Methods

A search for papers on the perioperative care of obese patients (English language only) was performed in July 2019 using the PubMed, Scopus, Web of Science and Cochrane Library electronic databases. The review focused on the results of RCTs, although observational studies, meta-analyses, reviews, guidelines and other reports discussing the perioperative care of obese patients were also considered. When data from obese patients were not available, relevant data from non-obese populations were used.

Results and conclusion

Obese patients require comprehensive preoperative evaluation. Experienced medical teams, appropriate equipment and monitoring, careful anaesthetic management, and an adequate perioperative ventilation strategy may improve postoperative outcomes. Additional perioperative precautions are necessary in patients with severe morbid obesity, metabolic syndrome, untreated or severe obstructive sleep apnoea syndrome, or obesity hypoventilation syndrome; patients receiving home ventilatory support or postoperative opioid therapy; and obese patients undergoing open operations, long procedures or revisional surgery.

Thromboelastography Values Remain Hypercoagulative 6 Months After Obesity Surgery: a Pilot Study

PURPOSE

Obesity causes a prothrombotic state and is known as a predisposing factor for thromboembolic events. In this pilot study, we assessed the impact of surgery for obesity and the subsequent weight loss on blood coagulation using traditional coagulation tests and thromboelastography (TEG).

MATERIAL AND METHODS

We studied blood samples from 18 patients receiving bariatric surgery. Besides traditional blood coagulation tests and high-sensitivity C-reactive protein (hsCRP) as a marker of inflammation, the TEG parameters reaction time (R), kinetics time (K), angle (α), maximum amplitude (MA), clot strength (G), and lysis percent at 60 min (LY60) were determined preoperatively and on the first postoperative day and 6 months after surgery.

RESULTS

Altogether, 54 samples were analyzed. The median MA (71.3 mm), G (12,403.3 d/sc), and hsCRP (3.5 mg/l) were elevated preoperatively. The median hsCRP further increased on the first day postoperatively, but declined to the normal range 6 months after surgery, while MA and G remained elevated. In traditional coagulation tests, there was an increase in median fibrinogen and D-dimer postoperatively. D-dimer normalized (0.4 mg/l) during the study period, while the fibrinogen level (4.1 g/l) remained above the upper limit of normal.

CONCLUSIONS

Measured by TEG, patients receiving bariatric surgery have hemostatic abnormalities indicating hypercoagulation at the 6-month follow-up visit, suggesting an elevated risk for thromboembolic events for at least 6 months after surgery.

A preliminary study using rotational thromboelastometry to investigate perioperative coagulation changes and to identify hypercoagulability in obese patients undergoing total hip or knee replacement

Surgery and obesity are known risk factors for thromboembolic events due to the presence of a hypercoagulable state. Rotational thromboelastometry is a viscoelastic assay that can provide a measure of hypercoagulability via a comprehensive assessment of the coagulation process. This prospective study investigates haemostatic changes over time, presence of hypercoagulability and the association between body mass index and thromboelastometry results in patients undergoing major orthopaedic surgery. Fifty adult patients undergoing total hip or knee replacement surgery had serial thromboelastometry measures performed prior to and following surgery, and on postoperative days 1 and 3. A hypercoagulable state, defined by an ExTEM maximum clot firmness G score ≥11 dyne/cm2, was present in 28% of the patients at baseline. The mean ExTEM maximum clot firmness G score increased by an average of three units from 10 (95% confidence interval (CI) 9–11) dyne/cm2 at baseline to 13 (95% CI 13–14) dyne/cm2 on postoperative day 3, with 85% of patients having a G score ≥11 dyne/cm2. A decrease in ExTEM and InTEM clot formation time and an increase in ExTEM, InTEM and FibTEM clot amplitude at 10 minutes, alpha angle and maximum clot firmness were observed by postoperative day 3 ( P <  0.001). There was no significant difference in the mean thromboelastometry values between patients with a body mass index <35 kg/m2or ≥35 kg/m2. Although a modest association between body mass index and the ExTEM maximum clot firmness G score was observed with exploratory data analysis, further study is required in a large cohort to test the effects of confounders, validate these findings, and determine their clinical importance.

Association Between Residual Platelet Reactivity on Clopidogrel Treatment and Severity of Coronary Atherosclerosis: Intrinsic Hypercoagulability as a Mediator

INTRODUCTION

High on-treatment residual platelet reactivity (HRPR) was associated with greater atherosclerosis burden. We examined whether intrinsic hypercoagulability (IHC) could be attributed to that association in patients treated by drug-eluting stents.

METHODS

This retrospective observation enrolled a total of 891 coronary artery disease (CAD) subjects. Platelet and coagulant reactivity was measured by thrombelastography. At least 24 h after a 300-mg dose of clopidogrel, adenosine diphosphate (ADP)-induced maximum amplitude of clot strength (MA_adp) > 47 mm represented HRPR. Thrombin-induced platelet-fibrin clot strength (MA_thrombin) and blood fibrinogen surrogated intrinsic coagulability. Using mediation analysis to evaluate the effect of IHC on the relationship between the number of narrowed coronaries and HRPR on clopidogrel.

RESULTS

More HRPR on clopidogrel and higher intrinsic coagulability were observed in more severe coronary atherosclerosis, especially in the three-vessel disease. After adjustment for confounding factors, the number of narrowed coronaries (OR_adj = 1.343, 95% CI 1.063-1.695, p = 0.013), MA_thrombin (OR_adj = 1.106, 95% CI 1.058-1.157, p < 0.001), and fibrinogen (OR_adj = 1.003, 95% CI 1.001-1.005, p = 0.012) were all independent positive predictors for HRPR. MA_thrombin and fibrinogen were meaningful mediators for the significant positive association of the number of narrowed vessels and HRPR on clopidogrel, which were enhanced by around 30% and 43%, respectively, for this effect.

CONCLUSIONS

This is the first study to demonstrate that the positive correlation between the number of stenotic coronaries and HRPR on clopidogrel may be partly attributed to IHC, which may enhance the risk stratification, guide more precise coagulation in multi-vessel disease after drug-eluting stents, and therefore deserve further study.

The Influence of Inflammation on Fibrinogen Turnover and Redistribution of the Hemostatic Balance to a Prothrombotic State in High On-Treatment Platelet Reactivity-Dual Poor Responder (HTPR-DPR) Patients

Knowledge about the influence of inflammation on platelet function and relocation of hemostatic balance to hypercoagulable state is still unclear. We compared two groups of patients who suffer from acute vs. chronic inflammatory process and additionally present high on-treatment platelet reactivity-dual platelet resistance. We did not found any differences in platelet aggregation between both investigated groups, but patients who suffer from chronic inflammation presented stronger relocation of the hemostatic balance to the hypercoagulability. A high concentration of prothrombin fragment F1+2 together with higher activity of von Willebrand factor in critical limb ischemia shows more exaggerated fibrinogen turnover although the blood concentration of this factor was in normal range. We concluded that high on-treatment platelet reactivity-dual platelet resistance and intensified inflammation are linked with elevated platelet and fibrinogen turnover to counteract proper hemostatic balance in favor of a prothrombotic state.

Effectiveness and safety of thromboprophylaxis with enoxaparin for prevention of pregnancy-associated venous thromboembolism

Essentials Thromboprophylaxis is offered to women considered to be at risk from pregnancy-associated venous thromboembolism (PA-VTE) but there is a suggestion that standard doses of low-molecular-weight heparin may not be effective. We conducted a large observational cohort study reviewing maternal outcomes in women who received extended thromboprophylaxis with enoxaparin for prevention of PA-VTE. We report a low rate of breakthrough VTE in women, the majority of whom received standard doses of enoxaparin. High rates of postpartum hemorrhage are reported in our cohort. Our data do not strongly support a move to increase doses of thromboprophylaxis for prevention of PA-VTE and raise the possibility that higher doses may increase bleeding complications and limit women's access to neuraxial analgesia/anesthesia.

BACKGROUND

Low-molecular-weight heparin is used to prevent pregnancy-associated venous thromboembolism (PA-VTE), but there are limited data to inform which women require thromboprophylaxis in pregnancy and debate about which low-molecular-weight heparin dose is effective and safe.

AIMS

To evaluate the efficacy and rate of complications using enoxaparin for thromboprophylaxis in a cohort of women at risk of PA-VTE managed between 1999 and 2014 at National Women's Hospital, a tertiary obstetric referral center in Auckland, New Zealand.

METHODS

A retrospective, observational study of women who received thromboprophylaxis with enoxaparin for prevention of PA-VTE while under the care of the obstetric or maternal fetal medicine team.

RESULTS

A total of 172 pregnancies in 123 women were identified. A single daily dose of 40 mg enoxaparin was used in 94.8% of pregnancies. Two breakthrough PA-VTEs occurred (1.2% [95% confidence interval, 0.32-4.14]). Postpartum hemorrhage ≥500 mL was reported in 36.6% of births and postpartum hemorrhage ≥1000 mL in 9.3% of births. Only four women were transfused. Neuraxial analgesia/anesthesia was used in 52.4% of births, including 39.6% of vaginal births.

CONCLUSION

Use of standard doses enoxaparin thromboprophylaxis in our cohort was effective at preventing PA-VTE. Neuraxial analgesia/anesthesia was used frequently during labor and birth;, using higher doses of enoxaparin may limit access to this. Postpartum hemorrhage was common and higher doses of thromboprophylaxis may increase obstetric bleeding complications. These data do not suggest an urgent need to consider higher doses of enoxaparin for thromboprophylaxis in this clinical setting.

A review of global coagulation assays - Is there a role in thrombosis risk prediction?

Normal haemostasis requires maintenance of a careful equilibrium between the necessity to clot when bleeding and the retention of fluid phase at all other times. Disruption of this equilibrium can result in catastrophic outcomes, e.g. acute myocardial infarction and pulmonary embolism. However, despite the significant therapeutic advances in cardiovascular medicine over recent years, our ability to provide an accurate cardiovascular risk assessment remains an unmet need. Routine coagulation testing is not a useful reflection of haemostasis and cannot be reliably used to predict bleeding and thrombosis risks. Global coagulation assays such as viscoelastic testing, thrombin and fibrin generation have been proposed as better measures of the haemostatic function. These assays, particularly viscoelastic testing, have been increasingly used to assess bleeding risks and guide blood product replacement in trauma and massive transfusion settings. However, the role of these assays in thrombosis is less well-defined but given the complexities of the coagulation system, these global coagulation assays when used in combination may provide a better assessment of cardiovascular and thrombosis risk at an individual level. Hence, we explore the role of some of the currently available global coagulation assays - the viscoelastic, thrombin generation and fibrin generation tests - and provide a review of the literature of the current evidence for these assays specifically in the field of venous thromboembolism and cardiovascular diseases.

Can Rotational Thromboelastometry be a New Predictive Tool for Retinal Vein Occlusion Development?

PURPOSE

To evaluate clotting dynamics by a new tool called rotational tromboelastometry (ROTEM) in retinal vein occlusion.

MATERIALS AND METHODS

Thirty-six patients who were diagnosed with retinal vein occlusion and 43 age and sex matched healthy controls were included in this study. Diabetes and use of anticoagulant therapy were exclusion criteria. All study participants underwent detailed ophthalmologic and systemic medical examination, including blood pressure measurement, hemoglobin-hematocrit levels, platelet count, coagulation parameters including prothrombin time, activated partial thromboplastin time, fibrinogen levels, and D-dimer levels. Peripheral blood samples were collected and analyzed with ROTEM Coagulation Analyzer (Tem International, Munich, Germany).

RESULTS

The RVO patients and controls did not differ with respect to age, sex, hemoglobin, hematocrit, platelet numbers, prothrombin time, activated partial thromboplastin time, fibrinogen levels, D-dimer levels, and glucose levels. When extrinsic thromboelastometry results were analyzed, RVO patients showed a significantly decreased clotting time (76.5 ± 15.0 vs. 95.0 ± 21 s, respectively; p = 0.01) and clot formation time (83.3 ± 22 vs. 99.7 ± 24s; p = 0.01) as compared with healthy controls. Other ROTEM parameters did now show any difference between two groups.

CONCLUSION

Patients with retinal vein occlusion showed faster clotting time and shorter clotting formation time as compared with healthy controls. ROTEM detects the altered clotting dynamics and may be a useful tool to elucidate the disease pathophysiology. Further studies are needed to investigate if it can be used as a screening test for individuals who are under risk to develop RVO or as a first step test to evaluate hypercoagulable state in RVO.

Platelet reactivity in overweight and obese patients undergoing cardiac surgery

Body mass index (BMI) and specifically overweight and obesity have been associated with an increased platelet reactivity in different series of patients. This information is derived by different laboratory platelet function tests (PFTs) like mean platelet volume (MPV), platelet microparticles, thromboxane B2 metabolites, and others. Point-of-care PFT, which are often used in cardiac surgery, are rarely addressed. The present study aims to verify platelet reactivity using multiple-electrode aggregometry (MEA) as a function of BMI in cardiac surgery patients. One-hundred ninety-eight cardiac surgery patients free from the effects of drugs acting on the P2Y₁₂ receptor and undergoing cardiac surgery received MEA-PFT immediately before surgery. Platelet reactivity was compared between normal weight and overweight-obese subjects. There were 99 underweight/normal (BMI < 25), 60 overweight (BMI ≥ 25) and 39 obese (BMI ≥ 30) patients. Overweight-obese patients did not show higher platelet counts nor a clear platelet hyper-reactivity, when tested with MPV and MEA ADP test. At TRAPtest, the overweight/obese patients had a significantly (P = 0.011) higher platelet reactivity (median 118, interquartile range 106-136) than controls (median 112, interquartile range 101-123) and a higher rate of platelet hyper-reactivity (odds ratio 2.19, 95% confidence interval 1.15-4.16, P = 0.016) in a multivariable model. A minor association was found between the BMI and platelet reactivity at TRAPtest, with a higher degree of activity for increasing BMI. The BMI determines an increased thrombin-dependent platelet reactivity in cardiac surgery patients. Thrombin is extensively formed during cardiac surgery, and this may explain the lower postoperative bleeding observed in obese patients in previous studies.

On-treatment platelet reactivity in peripheral and coronary blood in patients undergoing primary PCI for ST-segment elevation myocardial infarction (STEMI)

Dual antiplatelet therapy is recommended in patients undergoing primary percutaneous coronary intervention (p-PCI) for ST-segment elevation myocardial infarction (STEMI). Pre-analytical variables may influence platelet function analysis results. Our aim was to evaluate the on-treatment platelet reactivity in peripheral artery vs coronary blood in patients with STEMI. We enrolled one hundred and nine patients who consecutively underwent p-PCI at Cardiology Unit of Padua University Hospital between June 2014 and June 2015. Before the procedure, all patients received intravenous aspirin 250 mg and either of the thienopyridines; clopidogrel 600 mg, prasugrel 60 mg or ticagrelor 180 mg. ASPI-test and ADP-test using multiple electrode aggregometry (MEA) were performed in samples collected from both a peripheral artery and the culprit coronary artery. 'Low responders' were patients with an ASPI-test or ADP-test value greater than or equal to a pre-established normal range. No significant differences were observed in ASPI-test values between peripheral (19 (median) [3-49 (10-90 percentiles)] U) vs coronary (12 [1-40] U, p = .06) blood and in ADP-test (40 [14-82] U vs 33 [7-79] U, p =.68) blood. In peripheral blood, fifteen (14%) patients were 'low aspirin' and forty-one (38%) 'low thienopyridines' responders. The prevalence of 'low clopidogrel' responders was higher (45%) than prasugrel (36%) and ticagrelor (33%). Similar results were observed in coronary blood. In patients undergoing p-PCI for STEMI, MEA platelet function observed in coronary arteries was consistent with peripheral artery blood's independently of the antiplatelet drug used. The clinical significance of peripheral and coronary on-aspirin/thienopyridines platelet reactivity needs further clarification.

Endothelial Cell-derived Extracellular Vesicles Size-dependently Exert Procoagulant Activity Detected by Thromboelastometry

Endothelial cells (ECs) are major modulators of hemostasis by expressing and releasing pro- and anticoagulant mediators into the circulation. Previous studies showed that cultured ECs release procoagulant mediators into cell culture supernatants as evidenced by the reduction of viscoelastic clotting time. This effect was reversed with an anti-tissue factor antibody. Here, we aimed to investigate whether tissue factor (TF) was released by endothelial-derived extracellular vesicles (EVs) and which portion of the released vesicles displays the most prominent procoagulant properties. After stimulation of ECs with tumor-necrosis factor-α (TNF-α) the supernatants of EC cultures were subjected to differential centrifugation steps to collect larger and smaller EVs which were then characterised by nanoparticle tracking analysis (NTA) and flow cytometry. Mixed with fresh human blood and analysed by thromboelastometry EVs exerted a significant procoagulant stimulus, which could be partly reversed by addition of an anti-TF antibody. Moreover, TF activity was confirmed in the centrifuged fractions. In summary, our results provide evidence of the procoagulant potential of smaller and larger endothelial-derived EV fractions detected by thromboelastometry. The observed effect is most likely due to the release of TF-bearing EVs of different dimensions, which are released upon TNF-α stimulation of endothelial cell cultures.

Monitoring of Hypercoagulability by Thromboelastography in Bariatric Surgery

Background

Obesity is known as a major risk factor for postoperative vein thrombosis. Thromboelastography (TEG) is used to monitor viscoelastic features of blood clots. The aim of this study was to determine hypercoagulable states in patients undergoing bariatric surgery and to assess dynamics of coagulation parameters in the perioperative setting using TEG.

Material/Methods

We included 60 consecutive patients undergoing bariatric surgery. TEG alterations were assessed at 4 time points: at baseline, after the surgery, and on postoperative day 1 (POD1) and 2 (POD2). Hypercoagulable state was defined when patients showed clot strength (G) of ≥11 dynes/cm² or maximum amplitude (MA) ≥68 mm.

Results

Fourteen patients (23.3%) out of 60 showed hypercoagulability prior to surgery on TEG. Fibrinogen levels were significantly higher in the G ≥11 group compared to the G <11 group, at 4.2 and 3.8 g/l, respectively (p=0.02). Seventeen patients (28.3%) had MA ≥68 mm at baseline. Fibrinogen levels increased significantly from 3.90 at baseline to 4.16 g/l in POD2 (p<0.001). There was an increase in mean reaction time from baseline (6.74 s) to POD2 (7.43 s, p=0.022). We found a correlation between baseline fibrinogen levels and MA (R=0.431, p=0.001) or G (R=0.387, p=0.003). ROC curve analysis showed that fibrinogen levels can predict clot strength (G) ≥11 dynes/cm² with AUC=0.680 (p=0.044).

Conclusions

A considerable proportion of patients referred to bariatric surgery show a trend towards hypercoagulability on TEG. This study shows the potential of hypercoagulation monitoring by TEG in the perioperative setting of bariatric surgery.

Introduction of thromboelastometry-guided administration of fresh-frozen plasma is associated with decreased allogeneic blood transfusions and post-operative blood loss in cardiopulmonary-bypass surgery

BACKGROUND

Cardiac surgery is frequently associated with excessive blood loss requiring multiple blood transfusions which are, in turn, associated with increased morbidity and mortality. We evaluated the effectiveness of rotational thromboelastometry (ROTEM^®)-guided administration of fresh-frozen plasma (FFP) with regards to blood loss, transfusion requirements, and major post-operative complications.

MATERIALS AND METHODS

Coagulation management in 68 prospective patients undergoing cardiac surgery with cardiopulmonary bypass was based on a treatment algorithm guided by ROTEM^® measurements. The primary end-point was blood loss at 24 hours after surgery. Secondary end-points were: (i) need for allogeneic blood products after cardiopulmonary bypass and 24 hours post-operatively, and (ii) post-operative complications until discharge. The results were compared with those of a retrospective, control group of 69 patients who received empirical coagulation management before implementation of the ROTEM^®-guided algorithm.

RESULTS

Although patients with significantly lower haemoglobin levels received less packed red blood cells (PRBC) (840 vs 1,120 mL; p=0.031) and FFP (480 vs 720 mL; p=0.007) after introduction of the ROTEM^® algorithm, the intra-operative blood loss and post-operative haemoglobin levels were similar in the ROTEM^® and the retrospective control groups. In addition to significantly reduced blood loss and decreased requirements for PRBC (30.8 vs 62.3%; p<0.001) and FFP (25.0 vs 56.5%; p<0.001), the amounts of PRBC (315 vs 840 mL; p<0.001) and FFP (480 vs 840 mL; p=0.001) received during the first 24 hours after surgery were significantly reduced in the ROTEM^® group, as was the duration of post-operative hospitalisation.

DISCUSSION

Compared with empirical treatment, timely ROTEM^®-guided FFP administration during cardiac surgery can reduce not only overall blood product use and blood loss but also the duration of hospitalisation.

Platelet reactivity in thromboelastometry. Revision of the FIBTEM test: a basic study

This study aimed to investigate modifications to the FIBTEM test to better assess fibrinogen levels and the quality of fibrin polymerization in citrated blood using Multiplate impedance aggregometry to verify platelet inhibition. Blood samples from 26 healthy volunteers were subjected to thromboelastometry studies (EXTEM/FIBTEM tests) in accordance with the standard study protocol (cytochalasin D) and according to a modified protocol (synthetic IIbIIIa receptor antagonist vs. acetylsalicylic acid [ASA] + synthetic IIbIIIa receptor antagonist instead of cytochalasin D). Independent of thromboelastometry, Multiplate impedance aggregometry was used to assess the degree of restriction by the platelet blocked with the following treatments: (1) cytochalasin D, (2) synthetic IIbIIIa antagonist or (3) ASA + synthetic IIbIIIa antagonist to assess the aggregation response to activation with an agonist (ADP, collagen, thrombin receptor activating peptide-6 [TRAP-6], and arachidonic acid). Via aggregometry, cytochalasin D more weakly inhibited platelet aggregation than simultaneous administration of the -IIbIIIa receptor antagonist with ASA. However, total platelet aggregation inhibition was observed after simultaneous administration of cytochalasin D combined with a synthetic IIbIIIa receptor antagonist. In the thromboelastometry, a significant decrease of the A10, A20 and MCF parameters were observed in the EXTEM/FIBTEM tests after they were modified by the addition of a synthetic IIbIIIa receptor antagonist alone or in combination with ASA. In conclusion, in this Multiplate- and ROTEM-based laboratory approach, a two-way blockade (IIbIIIa-antagonist + cytochalasine D) was sufficient to completely inhibit procoagulant platelet function as observed by aggregometry and thromboelastometry.

The use of frozen plasma samples in thromboelastometry

Thromboelastometry is increasingly used in the clinical and scientific setting. The use of frozen plasma samples may be useful in overcoming certain limitations such as local and timely availability. Whole blood (WB) samples of 20 healthy volunteers were obtained, and plasma was generated. NATEM (n = 20), EXTEM (n = 20) and INTEM (n = 8) analyses were performed in WB, fresh plasma and frozen and thawed plasma. Dabigatran (500, 1000 ng/ml), rivaroxaban (100, 200 ng/ml) or alteplase (333 ng/ml) were added ex vivo to WB, and thromboelastometry was performed in WB and in frozen and thawed plasma samples. Clot formation time, mean clot firmness and the area under the curve were significantly altered in plasma compared to WB. In INTEM and EXTEM analysis, clotting time (CT) was comparable between WB (100%) and fresh (INTEM 114% and EXTEM 93%, ratio of the means) and frozen plasma samples (85 and 99%), whereas in NATEM analysis, the CT increased in fresh (193%) and frozen plasma samples (130%). Dabigatran dose-dependently increased the CT approximately 5- and 9-fold in WB and even more pronounced 10- and 26-fold in plasma. Accordingly, rivaroxaban dose-dependently increased the CT 2- and 2.7-fold in WB, and 3.5- and 4-fold in plasma samples. Hyperfibrinolysis was achieved by addition of alteplase in all WB samples and was reproducible in plasma samples. In conclusion, thromboelastometry, especially INTEM and EXTEM analyses, is possible using frozen and stored plasma samples with comparable results to the corresponding whole blood samples.