Phenotypes of Disseminated Intravascular Coagulation.

Two phenotypes of disseminated intravascular coagulation (DIC) are systematically reviewed. DIC is classified into thrombotic and fibrinolytic phenotypes characterized by thrombosis and hemorrhage, respectively. Major pathology of DIC with thrombotic phenotype is the activation of coagulation, insufficient anticoagulation with endothelial injury, and plasminogen activator inhibitor-1-mediated inhibition of fibrinolysis, leading to microvascular fibrin thrombosis and organ dysfunction. DIC with fibrinolytic phenotype is defined as massive thrombin generation commonly observed in any type of DIC, combined with systemic pathologic hyperfibrinogenolysis caused by underlying disorder that results in severe bleeding due to excessive plasmin formation. Three major pathomechanisms of systemic hyperfibrinogenolysis have been considered: (1) acceleration of tissue-type plasminogen activator (t-PA) release from hypoxic endothelial cells and t-PA-rich storage pools, (2) enhancement of the conversion of plasminogen to plasmin due to specific proteins and receptors that are expressed on cancer cells and endothelial cells, and (3) alternative pathways of fibrinolysis. DIC with fibrinolytic phenotype can be diagnosed by DIC diagnosis followed by the recognition of systemic pathologic hyperfibrin(ogen)olysis. Low fibrinogen levels, high fibrinogen and fibrin degradation products (FDPs), and the FDP/D-dimer ratio are important for the diagnosis of systemic pathologic hyperfibrin(ogen)olysis. Currently, evidence-based treatment strategies for DIC with fibrinolytic phenotypes are lacking. Tranexamic acid appears to be one of the few methods to be effective in the treatment of systemic pathologic hyperfibrin(ogen)olysis. International cooperation for the elucidation of pathomechanisms, establishment of diagnostic criteria, and treatment strategies for DIC with fibrinolytic phenotype are urgent issues in the field of thrombosis and hemostasis.

Safety of dobutamine or adenosine stress cardiac magnetic resonance imaging in patients with left ventricular thrombus.

BACKGROUND: Left ventricular (LV) thrombus formation is a common but potentially serious complication, typically occurring after myocardial infarction. Due to perceived high thromboembolic risk and lack of safety data, stress cardiac magnetic resonance (CMR) imaging especially with dobutamine is usually avoided despite its high diagnostic yield. This study aimed to investigate the characteristics, safety and outcome of patients with LV thrombus undergoing dobutamine or vasodilator stress CMR. METHODS: Patients undergoing stress CMR with concomitant LV thrombus were retrospectively included. Risk factors, comorbidities, and previous embolic events were recorded. Periprocedural safety was assessed for up to 48 h following the examination. Major adverse cardiac events (MACE) 12 months before the diagnosis were compared to 12 months after the exam and between patients and a matched control group. Additionally, patients were followed up for all-cause mortality. RESULTS: 95 patients (78 male, 65 ± 10.7 years) were included. Among them, 43 patients underwent dobutamine (36 high-dose, 7 low-dose) and 52 vasodilator stress CMR. Periprocedural safety was excellent with no adverse events. During a period of 24 months, 27 MACE (14.7%) occurred in patients and controls with no statistical difference between groups. During a median follow-up of 33.7 months (IQR 37.6 months), 6 deaths (6.3%) occurred. Type of stress agent, thrombus mobility, or protrusion were not correlated to embolic events or death. CONCLUSION: The addition of a stress test to a CMR exam is safe and does increase the generally high cardioembolic event rate in LV thrombus patients. Therefore, it is useful to support reperfusion decision-making.

Challenges in the diagnosis of the enigmatic primary adrenal leiomyosarcoma: two case reports and review of the literature.

BACKGROUND: Primary adrenal leiomyosarcoma is a rare and aggressive mesenchymal tumor derived from the smooth muscle wall of a central adrenal vein or its tributaries; therefore, tumors tend to invade the inferior vena cava and cause thrombosis. The great majority of tumors grow rapidly, which makes the disease difficult to diagnose in its early clinical stages and needs differentiation from adrenocortical carcinomas for the selection of chemotherapy including mitotane which causes adrenal insufficiency. CASE PRESENTATION: We presented two patients with adrenal leiomyosarcoma who were referred to our hospital with abdominal pain and harboring large adrenal tumors and inferior vena cava thrombosis. The endocrine findings, including serum catecholamine levels, were unremarkable. These two patients were considered clinically inoperable, and CT-guided core needle biopsy was performed to obtain the definitive histopathological diagnosis and determine the modes of therapy. The masses were subsequently diagnosed as primary adrenal leiomyosarcoma based on the histological features and positive immunoreactivity for SMA (smooth muscle actin), desmin, and vimentin. CONCLUSIONS: Adrenal leiomyosarcoma derived from the smooth muscle wall of a central adrenal vein or its tributaries is rare but should be considered a differential diagnosis in the case of nonfunctioning adrenal tumors extending directly to the inferior vena cava. CT-guided biopsy is considered useful for histopathological diagnosis and clinical management of patients with inoperable advanced adrenal tumors without any hormone excess.

[Predictive value of four items of new thrombus markers combined with conventional coagulation tests for thrombosis in antiphospholipid syndrome].

OBJECTIVE: To explore the predictive value of four items of new thrombus markers combined with conventional coagulation tests for thrombosis in antiphospholipid syndrome. METHODS: A total of 121 antiphospholipid syndrome (APS) patients who hospitalized at Peking University People's Hospital from March 2022 to January 2023 were selected and divided into thrombus group (50 cases) and nonthrombus group (71 cases) according to whether thrombosis occurred. The differences of laboratory characteristics including antiphospholipid antibodies were compared between the thrombotic and non-thrombotic groups. Chemiluminescent immunoassay was used to detect thrombomodulin (TM), thrombin-antithrombin complex (TAT), Plasmin-α2 plasmin inhibitor complex (PIC), and tissue plasminogen activator inhibitor complex (t-PAIC) in plasma from venous. The independent risk factors of thrombosis in patients with APS were determined using binary Logistic regression. Receiver operating characteristic (ROC) curve analysis was applied to evaluate the efficacy of each index on the prediction of thrombosis. RESULTS: Compared with the patients without thrombosis, the patients with thrombosis were older [49 (32, 64) years vs. 36 (32, 39) years, P < 0.05]. The percentages of male, smoking, hypertension, and global antiphospholipid syndrome score (GAPSS)≥10 in the patients with thrombosis were significantly higher than those in the patients without thrombosis (P < 0.05). The positive rates of anticardiolipin antibody (aCL) and lupus anticoagulant (LA) in the thrombotic group were significantly higher than those in the non-thrombotic group (P < 0.05), and the levels of prothrombin time, activated partial thromboplastin time, fibrinogen, fibrin degradation product in the thrombotic group were significantly higher than those in the non-thrombotic group (P < 0.05).Among the thrombosis group, venous thrombosis accounted for 19 (38.00%), including deep vein thrombosis (16, 84.21%) and pulmonary embolism accounted (5, 26.32%); Arterial thrombosis accounted for 35 (70.00%), including myocardial infarction (6, 17.14%) cerebral infarction (30, 85.71%). The patients in the thrombotic group had significantly greater TM levels than those in the non-thrombotic group (P < 0.05).There were no significant dif-ferences between the two groups in TAT (Z=-1.420, P=0.156), PIC (Z=-0.064, P=0.949), and t-PAIC (Z=-1.487, P=0.137). Univariate and binary Logistic regression analysis of relevant variables showed that advanced age [OR=1.126, P=0.002], elevated TM [OR=1.325, P=0.048], prolonged prothrombin time (PT) [OR=4.127, P=0.008] were independent risk factors for thrombosis in the patients with APS. ROC curve analysis of the above three independent risk factors showed that the combined detection of age, PT and TM had the highest Yoden index (0.727) and sensitivity (83.0%), with a specificity of 89.7%. CONCLUSION: TAT, PIC, TM, and t-PAIC may reflect thrombus formation from the coagulation system, fibrinolysis system, and endothelial system. The combined of age TM and PT is superior to the application of a single marker, which has diagnostic value for the early identification of APS thrombosis.

Viscoelastic Testing Methods.

Viscoelastic testing methods examine the real-time formation of a clot in a whole blood sample, and include thromboelastography (TEG), rotational thromboelastometry (ROTEM), and several other testing platforms. They allow for concurrent assessment of multiple aspects of clotting, including plasmatic coagulation factors, platelets, fibrinogen, and the fibrinolytic pathway. This testing is rapid and may be performed at the point-of-care, allowing for prompt identification of coagulopathies to guide focused and rational administration of blood products as well as the identification of anticoagulant effect. With recent industry progression towards user-friendly, cartridge-based, portable instruments, viscoelastic testing has emerged in the 21st century as a powerful tool to guide blood transfusions in the bleeding patient, and to identify and treat both bleeding and thrombotic conditions in many operative settings, including trauma surgery, liver transplant surgery, cardiac surgery, and obstetrics. In these settings, the use of transfusion algorithms guided by viscoelastic testing data has resulted in widespread improvements in patient blood management as well as modest improvements in select patient outcomes. To address the increasingly wide adoption of viscoelastic methods and the growing number of medical and laboratory personnel tasked with implementing, performing, and interpreting these methods, this chapter provides an overview of the history, physiology, and technology behind viscoelastic testing, as well as a practical review of its clinical utility and current evidence supporting its use. Also included is a review of testing limitations and the contextual role played by viscoelastic methods among all coagulation laboratory testing.

Anti-PF4 immunothrombosis without proximate heparin or adenovirus vector vaccine exposure.

ABSTRACT: Platelet-activating anti-platelet factor 4 (PF4)/heparin antibodies and anti-PF4 antibodies cause heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombocytopenia and thrombosis (VITT), respectively. Diagnostic and treatment considerations differ somewhat between HIT and VITT. We identified patients with thrombocytopenia and thrombosis without proximate heparin exposure or adenovirus-based vaccination who tested strongly positive by PF4/polyanion enzyme-immunoassays and negative/weakly positive by heparin-induced platelet activation (HIPA) test but strongly positive by PF4-induced platelet activation (PIPA) test (ie, VITT-like profile). We tested these patients by a standard chemiluminescence assay that detects anti-PF4/heparin antibodies found in HIT (HemosIL AcuStar HIT-IgG(PF4-H)) as well as a novel chemiluminescence assay for anti-PF4 antibodies found in VITT. Representative control sera included an exploratory anti-PF4 antibody-positive but HIPA-negative/weak cohort obtained before 2020 (n = 188). We identified 9 patients with a clinical-pathological profile of a VITT-like disorder in the absence of proximate heparin or vaccination, with a high frequency of stroke (arterial, n = 3; cerebral venous sinus thrombosis, n = 4), thrombocytopenia (median platelet count nadir, 49 × 109/L), and hypercoagulability (greatly elevated D-dimer levels). VITT-like serological features included strong reactivity by PIPA (aggregation <10 minutes in 9/9 sera) and positive testing in the novel anti-PF4 chemiluminescence assay (3/9 also tested positive in the anti-PF4/heparin chemiluminescence assay). Our exploratory cohort identified 13 additional patient sera obtained before 2020 with VITT-like anti-PF4 antibodies. Platelet-activating VITT-like anti-PF4 antibodies should be considered in patients with thrombocytopenia, thrombosis, and very high D-dimer levels, even without a proximate exposure to heparin or adenovirus vector vaccines.

THROMBOTIC MICROANGIOPATHY: DIAGNOSTIC CHALLENGES IN THE PRIMARY MULTIPLE NEOPLASM INVOLVEMENT WITH PREVALENT METASTASIS WITH GRANULOMATOSIS INFLAMMATORY FOCUSES.

Patient, who died during the hospital stay, had hemoblastosis and syphilis in the reported medical history. While the patient was examined doctors suspected the presence of malignancy with unknown primary localization with multiple metastatic injuries with clinical and laboratory TTP signs (hemorrhagic syndrome, thrombocytopenia, shystocytosis, and non-immune hemolytic anemia). Despite treatment, the general patient's condition progressively worsens with increasing multiple organ decompensation signs. In the final stage of the disease course, after heart arrest and the appearance of clinical death signs CPR measures were performed according to complete guidance, but CRP had no positive effect. Biological death was constated. Considering the criteria of the diagnostic clinical and laboratory dyad (thrombocytopenia and microangiopathic hemolytic anemia), the data of the patholog¬ical examination (multiple metastatic lesions, inflammatory process, tumor intoxication, thrombosis), the combination of manifestations of chronic myeloid leukemia, prostate cancer with multiple metastases, tertiary syphilis served as a condition for the initiation of TTP, which was of decisive importance in the development of the patient's death.

Lower limb arterial thrombosis in an adult with membranous glomerulonephritis.

Massive proteinuria and hypoalbuminemia are potential risk factors in thromboembolic complications. Venous thrombosis is a frequent complication of thromboembolism in patients with membranous glomerulonephritis, while arterial thrombosis is much less reported. A 35-year-old man presented with nephrotic syndrome and osteofascial compartment syndrome in the right lower limb due to arterial thrombosis. The biopsy findings were consistent with those of stage 2 membranous nephropathy. After immunotherapy (steroids and cyclosporine), the massive proteinuria, renal function, and serum albumin improved markedly. This is the first case of adult membranous glomerulonephritis with unilateral lower extremity arterial thrombosis diagnosed by renal biopsy and arteriography. It further confirms the high incidence of thromboembolic complications with membranous nephropathy.

A microfluidic approach for early prediction of thrombosis in patients with cancer.

Li and colleagues have made a notable advancement in predicting cancer-associated thrombosis with a microfluidic device that monitors circulating platelet activity.1 This tool could improve the management of thrombotic events in patients with cancer, guiding timely treatment and potentially reducing mortality.

Development and validation of a nomogram model for central venous access device-related thrombosis in hospitalized children.

This study aimed to develop and validate a nomogram model of central venous access device-related thrombosis (CRT) for hospitalized children. A total of 503 consecutive cases from a hospital in Changsha City, Hunan Province were stochastically classified into the training set and internal validation set at a ratio of 7:3, and 85 consecutive cases in two hospitals in Urumqi City, Xinjiang Uygur Autonomous Region were collected as an external validation set. Univariate analysis and multivariate analysis on CRT-related risk factors of hospitalized children were conducted, a logistic regression model was employed to establish the nomogram, and the discrimination, calibration, and decision curve analysis was performed to assess the proposed nomogram model. The nomogram model involved seven independent risk factors, including blind catheterization, abnormal liver function, central line-associated bloodstream infection, infection, number of catheter lines, leukemia, and bed rest > 72 h. The discrimination results showed that the area under the receiver operating characteristic curve of the training set, internal validation set, and external validation set was 0.74, 0.71, and 0.76 respectively, and the accuracy rates of the proposed nomogram model were 79%, 72%, and 71% in the training set, internal validation set, and external validation set. The calibration results also showed that the calibration curve had great fitness for each dataset. More importantly, the decision curve suggested that the proposed nomogram model had a prominent clinical significance. CONCLUSION: The nomogram model can be used as a risk assessment tool to reduce the missed diagnosis rate and the incidence of CRT in hospitalized children. WHAT IS KNOWN: • Central venous access device-related thrombosis is generally asymptomatic for hospitalized children, causing the missed diagnosis of central venous access device-related thrombosis easily. • No risk prediction nomogram model for central venous access device-related thrombosis in hospitalized children has been established. WHAT IS NEW: • A visual and personalized nomogram model was built by seven accessible variables (blind catheterization, abnormal liver function, central line-associated bloodstream infection, infection, number of catheter lines, leukemia, and bed rest > 72 h). • The model can effectively predict the risk of central venous access device-related thrombosis for hospitalized children.

Monitoring the Coagulation Profile of COVID-19 Patients Using Standard and ClotPro® Hemostasis Tests.

Background and Objectives: Coagulation disorders during COVID-19 infection are associated with a poorer prognosis and higher disease severity because thrombosis and inflammation are two processes that interfere with each other. A very important issue for clinicians is timely and adequate hemostasis and inflammation monitoring to prevent and treat potentially lethal consequences. The aim of this study was to identify specific hemostatic parameters that are associated with a higher risk of intrahospital mortality. Materials and Methods: This study was approved by the Ethics Committee of the Clinical Center Nis in Serbia. One hundred and forty-two patients presented with COVID-19 ARDS and were admitted to the ICU in the Clinic for Anesthesiology at the Clinical Center Nis from 14 April 2020 to 25 May 2020. Upon admission, blood was collected for biochemical and coagulation testing. The data obtained were analyzed using the Statistical Package for Social Sciences (SPSS v. 25, Chicago, IL, USA). Results: Among all the parameters assessed, older age; increased levels of fibrinogen, INR, D-dimer, and presepsin; and higher results in the platelet aggregation tests (aggregation induced by adenosine diphosphate based on the ADP test (AU/min), aggregation induced by arachidonic acid based on the ASPI test (AU/min), and aggregation induced by thrombin based on the TRAP test (AU/min)) and some assays of the viscoelastic test (clot amplitude after 5 min in the extrinsic coagulation pathway based on the A5 EX-test (mm), clot amplitude after 10 min in the extrinsic coagulation pathway based on the A10 EX-test (mm), clot amplitude after 5 min regarding functional fibrinogen based on the A5 FIB-test (mm), clot amplitude after 10 min regarding functional fibrinogen based on the A10 FIB-test (mm), and maximum clot firmness based on the MCF FIB-test (mm)); and lower values of viscoelastic clotting time in the extrinsic coagulation pathway based on the CT EX-test (s) were significantly correlated with mortality. In the multivariate analysis, D-dimer levels above 860 ng/mL, higher TRAP test value bins, and values above the normal reference range of the A10 FIB test were found to be independent predictors of mortality. Conclusions: Sophisticated hemostasis parameters can contribute to early risk assessment, which has initially been performed only on the basis of patients' clinical status. Hypercoagulability is the main coagulation disorder in COVID-19 infection.

Estrogen-based hormonal therapy and the risk of thrombosis in COVID-19 patients.

OBJECTIVE: Estrogen-containing contraceptives and hormone replacement therapy are used commonly, however, the risks of venous and arterial thrombosis imparted by such medications during COVID-19 infection or other similar viral infections remain undescribed. METHODS: To assess the risk of venous and arterial thrombosis in patients receiving oral estrogen-containing therapy (ECT) with COVID-19 as compared to those receiving non-estrogen-based hormonal therapy, we conducted a multicenter cohort study of 991 patients with confirmed COVID-19 infection, 466 receiving estrogen-containing hormonal therapy, and 525 receiving progestin-only or topical therapy. RESULTS: The use of estrogen-containing therapy was found to significantly increase the risk of venous thromboembolism (VTE) following COVID-19 diagnosis after controlling for age (HR 5.46 [95% CI 1.12-26.7, p = .036]). This risk was highest in patients over age 50, with 8.6% of patients receiving estrogen-containing therapy diagnosed with VTE compared to 0.9% of those receiving non-estrogen-based therapies (p = .026). The risk of arterial thrombosis was not significantly associated with oral estrogen use. CONCLUSIONS: These results suggest that estrogen-containing therapy is associated with a significantly increased risk of VTE in COVID-19 patients, especially in older individuals. These findings may guide provider counseling and management of patients with COVID-19 on estrogen-containing therapy.

Practice patterns in the management of pediatric iliofemoral arterial thrombosis.

BACKGROUND: Acute arterial thrombosis can be life- and limb-threatening. Most pediatric patients with iliofemoral arterial thrombosis are treated successfully with medical therapy; however, expert consensus is limited, and many recommendations are based on the extrapolation of adult data. We aim to understand treatment patterns and long-term outcomes after pediatric acute iliofemoral arterial thrombosis, from which management recommendations can be informed. METHODS: A single-institution retrospective study of pediatric patients diagnosed with iliofemoral arterial thrombosis from 2009 to 2018 was performed. Multiple parameters of management and follow-up were evaluated. Children anticoagulated for ≤28 days versus >28 days were compared. Data analysis used Fisher exact and Mann-Whitney U tests. RESULTS: Two hundred thirty-six children were included. Median age at diagnosis was 65 days (interquartile range 17-163), with 207 diagnosed as infants, 15 diagnosed between 1 to 2 years, and 14 diagnosed between 2 to 16 years. The median treatment duration was 28 days (interquartile range 13-42); patients treated for >28 days had a longer time for thrombus resolution, and more follow-up ultrasounds were performed. Limb length discrepancy did not differ between the groups (1.0% vs 6.3%, P = .06), and no patients were documented to have developed peripheral arterial disease over a median 6.5-year follow-up. Multiple treatment strategies were employed, the most common being heparin bridged to enoxaparin (25.0%) and enoxaparin monotherapy (21.6%). Eight patients (3.4%) underwent surgical intervention. CONCLUSION: Pediatric iliofemoral arterial thrombosis is primarily a disease of infants treated adequately with heparin or enoxaparin, infrequently requires surgical intervention, and is rarely associated with long-term complications. When guided by thrombus resolution on ultrasound, a four-week or shorter course of anticoagulation does not increase the need for surgical intervention or long-term complications.

Design and characterization of antithrombotic ClEKnsTy-Au nanoparticles as diagnostic and therapeutic reagents.

Thrombosis can cause various cardiovascular diseases, which seriously endanger human life. Development of diagnostic and therapeutic reagents for thrombosis at an early stage would be helpful for the improvement of treatment and the reduction of mortality. In the present study, based on an antithrombotic peptide lEKnsTy (lowercase letters represent D-amino acid residues), a diagnostic and therapeutic reagent targeting collagen and the early stage of thrombosis was proposed, where cysteine was introduced into the amino terminus of lEKnsTy to prepare ClEKnsTy, followed by coupling with AuNPs to prepare nanoconjugate AuNP-Cl. The binding of AuNP-Cl on the collagen surface was then confirmed by the molecular dynamics simulations of the binding of ClEKnsTy on collagen, and the experimental results of the binding of AuNP-Cl on collagen. The inhibition of platelet adhesion on the collagen surface by AuNP-Cl was also confirmed. Moreover, the good imaging ability of AuNP-Cl was confirmed by dark-field microscopy. These results indicated that AuNP-Cl was a potential effective diagnostic and therapeutic reagent targeting collagen, which would be helpful for the research and development of multifunctional antithrombotic reagents.

Growth differentiation factor-15 and prediction of cancer-associated thrombosis and mortality: a prospective cohort study.

BACKGROUND: Patients with cancer are at increased risk of venous thromboembolism (VTE) and arterial thromboembolic/thrombotic events (ATEs). Growth differentiation factor-15 (GDF-15) improves cardiovascular risk assessment, but its predictive utility in patients with cancer remains undefined. OBJECTIVES: To investigate the association of GDF-15 with the risks of VTE, ATE, and mortality in patients with cancer and its predictive utility alongside established models. METHODS: The Vienna Cancer and Thrombosis Study (CATS)-a prospective, observational cohort study of patients with newly diagnosed or recurrent cancer-which was followed for 2 years, served as the study framework. Serum GDF-15 levels at study inclusion were measured, and any association with VTE, ATE, and death was determined using competing risk (VTE/ATE) or Cox regression (death) modeling. The added value of GDF-15 to established VTE risk prediction models was assessed using the Khorana and Vienna CATScore. RESULTS: Among 1531 included patients with cancer (median age, 62 years; 53% men), median GDF-15 levels were 1004 ng/L (IQR, 654-1750). Increasing levels of GDF-15 were associated with the increased risks of VTE, ATE, and all-cause death ([subdistribution] hazard ratio per doubling, 1.16 [95% CI, 1.03-1.32], 1.30 [95% CI, 1.11-1.53], and 1.57 [95% CI, 1.46-1.69], respectively). After adjustment for clinically relevant covariates, the association only prevailed for all-cause death (hazard ratio, 1.21; 95% CI, 1.10-1.33) and GDF-15 did not improve the performance of the Khorana or Vienna CATScore. CONCLUSION: GDF-15 is strongly associated with survival in patients with cancer, independent of the established risk factors. While an association with ATE and VTE was identified in univariable analysis, GDF-15 was not independently associated with these outcomes and failed to improve established VTE prediction models.

Intracardiac Thrombosis and Systemic Embolism in a Patient with Cardiac Amyloidosis in Sinus Rhythm.

Intracardiac thrombosis formation in patients in sinus rhythm is a rare phenomenon. An 84-year-old woman was admitted because of worsening dyspnea on exertion. An electrocardiogram showed sinus rhythm, left atrial overload, marked left axis deviation, low voltage, and poor r-wave progression in leads V1-4. An echocardiogram showed relatively preserved left ventricular ejection fraction with minimal wall thickening. Her serum level of B-type natriuretic peptide (931 pg/mL) was markedly elevated and a diagnosis of worsening heart failure was made. During the course of treatment for heart failure, she was complicated by acute abdominal aortic thromboembolism together with left atrial thrombus. An emergency abdominal aortic thrombectomy was followed by the removal of a left atrial thrombus 2 days later. Left ventricular biopsy performed during the surgery revealed amyloid deposits in the myocardial interstitium. Immunohistochemical study confirmed the diagnosis of transthyretin cardiac amyloidosis. It is postulated that the risk of intracardiac thrombosis and systemic embolism is increased even in sinus rhythm in patients with cardiac amyloidosis.

Serotonin Release Assay: Functional Assay for Heparin- and Vaccine-Induced (Immune) Thrombotic Thrombocytopenia.

The serotonin release assay (SRA) has been the gold-standard assay for detection of heparin-dependent platelet-activating antibodies and integral for the diagnosis for heparin-induced thrombotic thrombocytopenia (HIT). In 2021, a thrombotic thrombocytopenic syndrome was reported after adenoviral vector COVID-19 vaccination. This vaccine-induced thrombotic thrombocytopenic syndrome (VITT) proved to be a severe immune platelet activation syndrome manifested by unusual thrombosis, thrombocytopenia, very elevated plasma D-dimer, and a high mortality even with aggressive therapy (anticoagulation and plasma exchange). While the platelet-activating antibodies in both HIT and VITT are directed toward platelet factor 4 (PF4), important differences have been found. These differences have required modifications to the SRA to improve detection of functional VITT antibodies. Functional platelet activation assays remain essential in the diagnostic workup of HIT and VITT. Here we detail the application of SRA for the assessment of HIT and VITT antibodies.