PULMONARY MICROTHROMBOSIS IN SEVERE COVID-19: AUTOPSY-BASED STUDY

Abstract

Pulmonary microthrombosis has emerged as a significant contributor to respiratory failure and mortality in severe COVID-19. This autopsy-based study aimed to characterize the extent, distribution, and clinical associations of pulmonary microthrombi in patients who succumbed to SARS-CoV-2 infection. Autopsies were conducted on 40 deceased COVID-19 patients. Lung tissues were examined histologically and immunohistochemically to identify and quantify microthrombi. Clinical data, including coagulation biomarkers, comorbidities, and anticoagulation therapy, were retrospectively analyzed. Statistical analyses and multivariate logistic regression were performed to explore associations between thrombotic burden and clinical variables. Most of the time, microthrombi formed in the small blood vessels of the lungs and the lower lobes had the most.  According to histological observation, pathological changes included swelling of endothelial cells, development of hyaline membranes, thick fibrin that stuck platelets in the blood and lung oedema.  Using immunohistochemistry, researchers found excess expression of von Willebrand factor and tissue factor in the endothelium near areas of high thrombus deposits.  The amount of microthrombus found was increased when fibrinogen and D-dimer levels were higher (P < 0.01).  Microthrombi were found less frequently in patients on prophylactic or therapeutic anticoagulants (p = 0.04), however, patients with diabetes and hypertension had a greater number of thrombi.  Technology confirmed that 29% of patients with COVID-19 triggered blood clots in their brains, 42% in their hearts and 68% in their kidneys.  According to logistic regression, increased D-dimer (OR 3.2), high CRP (OR 2.4) and findings of endotheliitis in tissues (OR 2.7) were linked to the development of microthrombosis in the lungs.  Both clinically and in the long term, severe COVID-19 can increase the risk of dying by causing microthrombosis in the lungs.  COVID-19 is classified as a thromboinflammatory illness because of the activation of endothelial cells and widespread thrombi.  It is apparent from these results that finding and treating coagulopathy in high-risk COVID-19 patients is important as soon as possible.