ABSTRACT
BackgroundPatients with coronavirus disease 19 (COVID-19) are at high risk for thrombotic arterial and venous occlusions, while lung histopathology often reveals fibrin-based occlusion of small vessels in patients who succumb to the disease. At the same time, bleeding complications have been observed in some patients. Better understanding the balance between coagulation and fibrinolysis will help inform optimal approaches to thrombosis prophylaxis and potential utility of fibrinolytic-targeted therapies. ObjectiveTo evaluate fibrinolysis among a large cohort of hospitalized COVID-19 patients. Patients and methods118 hospitalized COVID-19 patients and 30 healthy controls were included in the study. We measured plasma antigen levels of tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) and performed spontaneous clot lysis assays. ResultsWe found markedly elevated levels of tPA and PAI-1 among patients hospitalized with COVID-19. Both factors demonstrated a strong correlation with neutrophil counts and markers of neutrophil activation, but not with D-dimer. High levels of tPA and PAI-1 were associated with worse respiratory status. High levels of tPA, in particular, were also strongly correlated with mortality and with a significant enhancement in spontaneous ex vivo clot lysis. ConclusionWhile both tPA and PAI-1 are elevated among COVID-19 patients, extremely high levels of tPA enhance spontaneous fibrinolysis and are significantly associated with mortality in some patients. These data indicate that fibrinolytic homeostasis in COVID-19 is complex with a subset of patients expressing a balance of factors that may favor fibrinolysis and suggests that further study of tPA as a potential biomarker is warranted.
