Vaccine-Associated Thrombocytopenia and Thrombosis: Venous Endotheliopathy Leading to Venous Combined Micro-Macrothrombosis.

Serious vaccine-associated side effects are very rare. Major complications of vaccines are thrombocytopenia and thrombosis in which pathogenetic mechanism is consistent with endotheliopathy characterized by "attenuated" sepsis-like syndrome, leading to the activation of inflammatory and microthrombotic pathway. In the COVID-19 pandemic, acute respiratory distress syndrome caused by microthrombosis has been the major clinical phenotype from the viral sepsis in association with endotheliopathy-associated vascular microthrombotic disease (EA-VMTD), sometimes presenting with thrombotic thrombocytopenic purpura (TTP)-like syndrome. Often, venous thromboembolism has coexisted due to additional vascular injury. In contrast, clinical phenotypes of vaccine complication have included "silent" immune thrombocytopenic purpura (ITP-like syndrome), multiorgan inflammatory syndrome, and deep venous thrombosis (DVT), cerebral venous sinus thrombosis (CVST) in particular. These findings are consistent with venous (v) EA-VMTD. In vEA-VMTD promoted by activated complement system following vaccination, "consumptive" thrombocytopenia develops as ITP-like syndrome due to activated unusually large von Willebrand factor (ULVWF) path of hemostasis via microthrombogenesis. Thus, the pathologic phenotype of ITP-like syndrome is venous microthrombosis. Myocarditis/pericarditis and other rare cases of inflammatory organ syndrome are promoted by inflammatory cytokines released from activated inflammatory pathway, leading to various organ endotheliitis. Vaccine-associated CVST is a form of venous combined "micro-macrothrombosis" composed of binary components of "microthrombi strings" from vEA-VMTD and "fibrin meshes" from vaccine-unrelated incidental vascular injury perhaps such as unreported head trauma. This mechanism is identified based on "two-path unifying theory" of in vivo hemostasis. Venous combined micro-macrothrombosis due to vaccine is much more serious thrombosis than isolated distal DVT made of macrothrombus. This paradigm changing novel concept of combined micro-macrothrombosis implies the need of combined therapy of a complement inhibitor and anticoagulant for CVST and other complex forms of DVT.

Predictors of in-hospital Outcomes in Patients With Cirrhosis and Coronavirus Disease-2019.

Background: Coronavirus disease-2019 (COVID-19) cases continue to increase globally. Poor outcomes in patients with COVID-19 and cirrhosis have been reported; predictors of outcome are unclear. The existing data is from the early part of the pandemic when variants of concern (VOC) were not reported. Aims: We aimed to assess the outcomes and predictors in patients with cirrhosis and COVID-19. We also compared the differences in outcomes between the first wave of pandemic and the second wave. Methods: In this retrospective analysis of a prospectively maintained database, data on consecutive cirrhosis patients (n = 221) admitted to the COVID-19 care facility of a tertiary care center in India were evaluated for presentation, the severity of liver disease, the severity of COVID-19, and outcomes. Results: The clinical presentation included: 18 (8.1%) patients had compensated cirrhosis, 139 (62.9%) acute decompensation (AD), and 64 (29.0%) had an acute-on-chronic liver failure (ACLF). Patients with ACLF had more severe COVID-19 infection than those with compensated cirrhosis and AD (54.7% vs. 16.5% and 33.3%, P < 0.001). The overall mortality was 90 (40.7%), the highest among ACLF (72.0%). On multivariate analysis, independent predictors of mortality were high leukocyte count, alkaline phosphatase, creatinine, child class, model for end-stage liver disease (MELD) score, and COVID-19 severity. The second wave had more cases of severe COVID-19 as compared to the first wave, with a similar MELD score and Child score. The overall mortality was similar between the two waves. Conclusion: Patients with COVID-19 and cirrhosis have high mortality (40%), particularly those with ACLF (72%). A higher leukocyte count, creatinine, alkaline phosphatase, Child class, and MELD score are predictors of mortality.

COVID-19 Sepsis: Pathogenesis and Endothelial Molecular Mechanisms Based on "Two-Path Unifying Theory" of Hemostasis and Endotheliopathy-Associated Vascular Microthrombotic Disease, and Proposed Therapeutic Approach with Antimicrothrombotic Therapy.

COVID-19 sepsis is characterized by acute respiratory distress syndrome (ARDS) as a consequence of pulmonary tropism of the virus and endothelial heterogeneity of the host. ARDS is a phenotype among patients with multiorgan dysfunction syndrome (MODS) due to disseminated vascular microthrombotic disease (VMTD). In response to the viral septicemia, the host activates the complement system which produces terminal complement complex C5b-9 to neutralize pathogen. C5b-9 causes pore formation on the membrane of host endothelial cells (ECs) if CD59 is underexpressed. Also, viral S protein attraction to endothelial ACE2 receptor damages ECs. Both affect ECs and provoke endotheliopathy. Disseminated endotheliopathy activates two molecular pathways: inflammatory and microthrombotic. The former releases inflammatory cytokines from ECs, which lead to inflammation. The latter initiates endothelial exocytosis of unusually large von Willebrand factor (ULVWF) multimers and FVIII from Weibel-Palade bodies. If ADAMTS13 is insufficient, ULVWF multimers activate intravascular hemostasis of ULVWF path. In activated ULVWF path, ULVWF multimers anchored to damaged endothelial cells recruit circulating platelets and trigger microthrombogenesis. This process produces "microthrombi strings" composed of platelet-ULVWF complexes, leading to endotheliopathy-associated VMTD (EA-VMTD). In COVID-19, microthrombosis initially affects the lungs per tropism causing ARDS, but EA-VMTD may orchestrate more complex clinical phenotypes, including thrombotic thrombocytopenic purpura (TTP)-like syndrome, hepatic coagulopathy, MODS and combined micro-macrothrombotic syndrome. In this pandemic, ARDS and pulmonary thromboembolism (PTE) have often coexisted. The analysis based on two hemostatic theories supports ARDS caused by activated ULVWF path is EA-VMTD and PTE caused by activated ULVWF and TF paths is macrothrombosis. The thrombotic disorder of COVID-19 sepsis is consistent with the notion that ARDS is virus-induced disseminated EA-VMTD and PTE is in-hospital vascular injury-related macrothrombosis which is not directly  related to viral pathogenesis. The pathogenesis-based therapeutic approach is discussed for the treatment of EA-VMTD with antimicrothrombotic regimen and the potential need of anticoagulation therapy for coinciding macrothrombosis in comprehensive COVID-19 care.

The Imperfect Cytokine Storm: Severe COVID-19 With ARDS in a Patient on Durable LVAD Support.

As health systems worldwide grapple with the coronavirus disease-2019 (COVID-19) pandemic, patients with durable LVAD support represent a unique population at risk for the disease. This paper outlines the case of such a patient who developed COVID-19 complicated by a "cytokine storm" with severe acute respiratory distress syndrome and myocardial injury and describes the challenges that arose during management.