Renal Thrombotic Microangiopathy: A Review.

Thrombotic microangiopathy (TMA), a pathological lesion observed in a wide spectrum of diseases, is triggered by endothelial injury and/or dysfunction. Although TMA lesions are often accompanied by clinical features of microangiopathic hemolytic anemia, thrombocytopenia, and ischemic end-organ injury, renal-limited forms of TMA are not infrequently encountered in clinical practice. The presence of renal-limited manifestations can be diagnostically challenging, often delaying the initiation of targeted therapy. Prompt investigation and empirical treatment of TMA is warranted to reduce associated morbidity and mortality. Major advances have been made with respect to the pathophysiology of primary TMA entities, with the subsequent development of novel diagnostic tools and lifesaving therapies for diseases like thrombotic thrombocytopenic purpura and complement-mediated TMA. This article will review the clinical presentation and pathologic hallmarks of TMA involving the kidney, and the disease-specific mechanisms that contribute to the endothelial injury that characterizes TMA lesions. Diagnostic approach and both empirical and disease-specific treatment strategies will be discussed, along with the potential role for emerging targeted disease-specific therapies.

Coronavirus Disease 2019-Associated Thrombotic Microangiopathy: Literature Review.

Coronavirus disease 2019 (COVID-19) can lead to clinically significant multisystem disorders that also affect the kidney. According to recent data, renal injury in the form of thrombotic microangiopathy (TMA) in native kidneys ranks third in frequency. Our review of global literature revealed 46 cases of TMA in association with COVID-19. Among identified cases, 18 patients presented as thrombotic thrombocytopenic purpura (TTP) and 28 cases presented as atypical hemolytic uremic syndrome (aHUS). Altogether, seven patients with aHUS had previously proven pathogenic or likely pathogenic genetic complement abnormalities. TMA occurred at the time of viremia or even after viral clearance. Infection with COVID-19 resulted in almost no or only mild respiratory symptoms in the majority of patients, while digestive symptoms occurred in almost one-third of patients. Regarding the clinical presentation of COVID-19-associated TMA, the cases showed no major deviations from the known presentation. Patients with TTP were treated with plasma exchange (88.9%) or fresh frozen plasma (11.1%), corticosteroids (88.9%), rituximab (38.9%), and caplacizumab (11.1%). Furthermore, 53.6% of patients with aHUS underwent plasma exchange with or without steroid as initial therapy, and 57.1% of patients received a C5 complement inhibitor. Mortality in the studied cohort was 16.7% for patients with TTP and 10.7% for patients with aHUS. The exact role of COVID-19 in the setting of COVID-19-associated TMA remains unclear. COVID-19 likely represents a second hit of aHUS or TTP that manifests in genetically predisposed individuals. Early identification of the TMA subtype and appropriate prompt and specific treatment could lead to good outcomes comparable to survival and recovery statistics for TMA of all causes.

Thrombotic microangiopathy in children.

The syndrome of thrombotic microangiopathy (TMA) is a clinical-pathological entity characterized by microangiopathic hemolytic anemia, thrombocytopenia, and end organ involvement. It comprises a spectrum of underlying etiologies that may differ in children and adults. In children, apart from ruling out shigatoxin-associated hemolytic uremic syndrome (HUS) and other infection-associated TMA like Streptococcus pneumoniae-HUS, rare inherited causes including complement-associated HUS, cobalamin defects, and mutations in diacylglycerol kinase epsilon gene must be investigated. TMA should also be considered in the setting of solid organ or hematopoietic stem cell transplantation. In this review, acquired and inherited causes of TMA are described with a focus on particularities of the main causes of TMA in children. A pragmatic approach that may help the clinician tailor evaluation and management is provided. The described approach will allow for early initiation of treatment while waiting for the definitive diagnosis of the underlying TMA.

Obstetric outcomes in pregnant COVID-19 women: the imbalance of von Willebrand factor and ADAMTS13 axis.

BACKGROUND: Thrombotic microangiopathy has been invoked as one of the most important mechanisms of damage in COVID-19 patients. Protease ADAMTS13 is a marker of microangiopathy responsible for controlling von Willebrand multimers size. Von Willebrand factor/ADAMTS13 ratio has been found impaired in COVID-19 patients outside pregnancy. METHODS: We prospectively investigated 90 pregnant women admitted to two tertiary academic hospitals in Italy with a laboratory-confirmed diagnosis of SARS-CoV-2 infection. Demographic, clinical information and routine laboratory data were collected at the hospital admission and until discharge. We investigated whether vonWillebrand /ADAMTS13 axis imbalance is a predictor of adverse outcomes. Logistic regression analysis, which controlled for potential confounders, was performed to evaluate the association between laboratory parameters and clinical outcomes. RESULTS: Most women (55.6%) were parae, with median gestational age at admission of 39 weeks. At hospital admission, 63.3% were asymptomatic for COVID-19 and 24.4% showed more than one sign or symptom of infection. Nulliparae with group O showed Willebrand / ADA MTS-13 ratios significantly lower than non-O, whereas in multiparae this difference was not observed. Logistic regression showed that ratio von Willebrand to ADAMTS13 was significantly and independently associated with preterm delivery (OR 1.9, 95%CI 1.1-3.5). CONCLUSION: This study shows an imbalance of vonWillebrand /ADAMTS13 axis in pregnant women with COVID-19, leading to a significantly higher and independent risk of preterm delivery. Monitoring these biomarkers might support decision making process to manage and follow-up pregnancies in this setting.

Fatal thrombotic microangiopathy with rhabdomyolysis as an initial symptom after the first dose of mRNA-1273 vaccine: A case report.

We report a case of a Japanese man with severe rhabdomyolysis and multiple thrombosis of arterioles after the first dose of mRNA-1273 vaccine. He developed rapidly progressive rhabdomyolysis and infarctions of multiple organs. Antiplatelet factor 4 antibody test was negative. Despite the intensive supportive care, including aggressive fluid administration, hemodialysis, administration of anticoagulants, high-dose steroid, and eculizumab, the patient ultimately died of multiple organ failure. Autopsy revealed multiple thrombosis in the arterioles and organ necrosis. Low serum complements and C3 deposition in the renal glomeruli detected by immunofluorescence suggested a possible immune-mediated mechanism. To our knowledge, this is the first case report of rhabdomyolysis and multiple thrombosis of the arterioles as an adverse event following COVID-19 vaccination.

Thrombotic Microangiopathy in Patients Recovering from COVID-19.

INTRODUCTION: During the pandemic caused by the SARS-CoV-2 virus, some patients who develop severe forms of COVID-19 present thrombotic microangiopathy in the course of the disease's clinical progression. METHODS: Data came from direct patient observation and clinical records. We performed a kidney biopsy and used optical microscopy and immunofluorescence techniques. RESULTS: We present the case of a 78-year-old male patient, mestizo, overweight with a history of high blood pressure, ischemic cardiopathy and chronic obstructive pulmonary disease who was first admitted to the hospital due to respiratory symptoms and diarrhea related to COVID-19, from which he recovered. He was subsequently readmitted with symptoms of acute renal dysfunction accompanied by mild anemia and thrombocytopenia; at the same time, he resulted negative for COVID-19 via a real-time polymerase chain reaction test. A kidney biopsy revealed thrombi in glomerular capillaries, acute tubular necrosis, thickening of extraglomerular blood vessel walls, and C3 deposits in the glomerular tufts. CONCLUSIONS: We describe a case of thrombotic microangiopathy with kidney biopsy in a patient recovering from COVID-19. Acute renal dysfunction is a form of thrombotic microangiopathy that has been observed in patients recovering from COVID-19.

Unusual pattern of thrombotic events in young adult non-critically ill patients with COVID-19 may result from an undiagnosed inherited and acquired form of thrombophilia.

In 145 previously healthy non-critically ill young adults, coronavirus disease 2019 (COVID-19)-related symptoms, risk factors for thrombosis, coagulation and inflammatory parameters were compared, with 29 patients reporting unusual thrombotic events (UTEs) and 116 not having thrombotic events. The inflammatory indices, coagulation and prothrombotic platelet phenotype (PTPP) were significantly higher in patients with UTEs versus those without. Patients with UTEs were categorised according to detection of thrombophilic genes (TGs), coagulation and inflammatory markers to the non-TG and TG subcohort. A total of 38 UTEs were identified, which included splanchnic vein thrombosis (SVT; 11), stroke (six), cerebral vein thrombosis (five), thrombotic microangiopathy (four), limb ischaemia and inferior vena cava thrombosis (three each), ST-segment elevation myocardial infarction (two), superior vena cava thrombosis (two), upper limb deep venous thrombosis and retinal vein thrombosis, one each. We found a 55% prevalence of TGs mainly heterozygous coagulation factor II, thrombin (FII)-G20210A, Janus kinase 2 (JAK2)-V617F, protein-S, and antithrombin III deficiency with a high (76·9%) prevalence of venous UTEs, multiple vessels thrombosis, and recurrence rate among the TG versus non-TG subcohort. The presence of JAK2-V617F, and FII-G20210A mutations was linked with SVT. Thrombosis in the non-TG subcohort was associated with more haemorrhagic problems, thrombosis progression and a significantly higher level of inflammatory markers, PTPP, mean platelet volume, von Willebrand factor, and factor VIII, which remained high for up to 6 months, as well as elevated D-dimer. Acquired and inherited thrombophilia with endotheliopathy appeared to be a relevant mechanism to explain the occurrence of UTEs that are not correlated to COVID-19 severity.

Thrombotic Microangiopathy Triggered by COVID-19: Case Reports.

SARS-CoV-2 causes thrombotic microangiopathy (TMA) through the activation of an alternative and lectin complement pathway. TMA is one of the main reasons for acute kidney injury development in patients with COVID-19. In this study, we present 3 TMA cases with severe kidney injury triggered by SARS-CoV-2. In the absence of other TMA causes, we diagnosed the atypical hemolytic uremic syndrome, triggered by SARS-CoV-2 due to abnormal complement activation. Because of both coagulation factors activation, and the high level of D-dimer in patients with COVID-19, it is crucial to differentiate disseminated intravascular coagulation from TMA. The use of anticomplement therapies such as eculizumab should be considered in refractory cases of progressive COVID-19. Controlled clinical trials are required before a definitive statement can be made.

A case of thrombotic thrombocytopenic purpura associated with COVID-19.

Acquired thrombotic thrombocytopenic purpura (TTP) is an autoimmune disease that can be triggered by different events, including viral infections. It presents as thrombotic microangiopathy and can lead to severe complications that often require management in the intensive care unit (ICU). We report a patient who presented with acquired TTP following COVID-19 infection. A 44-year-old woman presented to the emergency department with severe anemia, acute kidney injury and respiratory failure due to COVID-19. Clinical and laboratory findings were suggestive for thrombotic microangiopathy. On day 8 laboratory tests confirmed the diagnosis of acquired TTP. The patient needed 14 plasma exchanges, treatment with steroids, rituximab and caplacizumab and 18 days of mechanical ventilation. She completely recovered and was discharged home on day 51. Acquired TTP can be triggered by different events leading to immune stimulation. COVID-19 has been associated with different inflammatory and auto-immune diseases. Considering the temporal sequence and the lack of other possible causes, we suggest that COVID-19 infection could have been the triggering factor in the development of TTP. Since other similar cases have already been described, possible association between COVID and TTP deserves further investigation.

ADAMTS13 activity to von Willebrand factor antigen ratio predicts acute kidney injury in patients with COVID-19: Evidence of SARS-CoV-2 induced secondary thrombotic microangiopathy.

INTRODUCTION: Severe COVID-19 is often compounded by a prothrombotic state that is associated with poor outcomes. In this investigation, we aimed to evaluate ADAMTS13 activity, von Willebrand factor level (VWF:Ag), and the corresponding ADAMTS13 activity/VWF:Ag ratio, in patients with COVID-19 and for associations with disease progression and acute kidney injury (AKI). METHODS: Patients presenting to the emergency department (ED) with COVID-19 were enrolled in this prospective, observational study. ADAMTS13 activity and VWF:Ag were measured at index ED visit. The primary endpoint was severe AKI defined by KDIGO stage 2 + 3 criteria, while the secondary endpoint was peak 30-day COVID-19 severity. RESULTS: A total of 52 adult COVID-19 patients were enrolled. Overall, we observed that 23.1% of the cohort had a relative deficiency in ADAMTS13 activity, while 80.8% had elevated VWF:Ag. The ADAMTS13 activity/VWF:Ag ratio was significantly lower in patients with severe AKI (P = .002) and those who developed the severe form of COVID-19 (P = .020). The ADAMTS13 activity/VWF:Ag ratio was negatively correlated with age (P < .001) and LDH (P < .001), while positively correlated with hemoglobin (P = .041). After controlling for confounders, a one-unit increase in ADAMTS13/VWF:Ag ratio was associated with 20% decreased odds of severe AKI. CONCLUSION: A low ADAMTS13 activity:VWF:Ag ratio at ED presentation is associated with progression to severe COVID-19 disease and severe AKI, with a pattern suggestive of a secondary microangiopathy. Further interventional studies should be conducted to assess the restoration of ADAMTS13:VWF:Ag ratio in hospitalized patients with COVID-19.

COVID-19 Manifesting as Renal Allograft Dysfunction, Acute Pancreatitis, and Thrombotic Microangiopathy: A Case Report.

Coronavirus disease 2019 (COVID-19) is associated with high morbidity and mortality worldwide in both the general population and kidney transplant recipients. Acute kidney injury is a known complication of COVID-19 and appears to most commonly manifest as acute tubular injury on renal biopsy. Coagulopathy associated with COVID-19 is a known but poorly understood complication that has been reported to cause thrombotic microangiopathy on rare occasions in native kidneys of patients with COVID-19. Here, we report the first case of biopsy-proven thrombotic microangiopathy in a kidney transplant recipient with COVID-19 who developed acute pancreatitis and clinical features of microangiopathic hemolytic anemia. The patient recovered with supportive care alone.

Thrombocytopathy and endotheliopathy: crucial contributors to COVID-19 thromboinflammation.

The core pathology of coronavirus disease 2019 (COVID-19) is infection of airway cells by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that results in excessive inflammation and respiratory disease, with cytokine storm and acute respiratory distress syndrome implicated in the most severe cases. Thrombotic complications are a major cause of morbidity and mortality in patients with COVID-19. Patients with pre-existing cardiovascular disease and/or traditional cardiovascular risk factors, including obesity, diabetes mellitus, hypertension and advanced age, are at the highest risk of death from COVID-19. In this Review, we summarize new lines of evidence that point to both platelet and endothelial dysfunction as essential components of COVID-19 pathology and describe the mechanisms that might account for the contribution of cardiovascular risk factors to the most severe outcomes in COVID-19. We highlight the distinct contributions of coagulopathy, thrombocytopathy and endotheliopathy to the pathogenesis of COVID-19 and discuss potential therapeutic strategies in the management of patients with COVD-19. Harnessing the expertise of the biomedical and clinical communities is imperative to expand the available therapeutics beyond anticoagulants and to target both thrombocytopathy and endotheliopathy. Only with such collaborative efforts can we better prepare for further waves and for future coronavirus-related pandemics.

Multisystem Imaging Manifestations of COVID-19, Part 1: Viral Pathogenesis and Pulmonary and Vascular System Complications.

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) results in coronavirus disease 2019 (COVID-19), which was declared an official pandemic by the World Health Organization on March 11, 2020. The infection has been reported in most countries around the world. As of August 2020, there have been over 21 million cases of COVID-19 reported worldwide, with over 800 000 COVID-19-associated deaths. It has become apparent that although COVID-19 predominantly affects the respiratory system, many other organ systems can also be involved. Imaging plays an essential role in the diagnosis of all manifestations of the disease, as well as its related complications, and proper utilization and interpretation of imaging examinations is crucial. With the growing global COVID-19 outbreak, a comprehensive understanding of the diagnostic imaging hallmarks, imaging features, multisystemic involvement, and evolution of imaging findings is essential for effective patient management and treatment. To date, only a few articles have been published that comprehensively describe the multisystemic imaging manifestations of COVID-19. The authors provide an inclusive system-by-system image-based review of this life-threatening and rapidly spreading infection. In part 1 of this article, the authors discuss general aspects of the disease, with an emphasis on virology, the pathophysiology of the virus, and clinical presentation of the disease. The key imaging features of the varied pathologic manifestations of this infection that involve the pulmonary and peripheral and central vascular systems are also described. Part 2 will focus on key imaging features of COVID-19 that involve the cardiac, neurologic, abdominal, dermatologic and ocular, and musculoskeletal systems, as well as pediatric and pregnancy-related manifestations of the virus. Vascular complications pertinent to each system will be also be discussed in part 2. Online supplemental material is available for this article. ©RSNA, 2020.