Sustained prothrombotic changes in COVID-19 patients 4 months after hospital discharge

Patients with COVID-19 are at increased risk of thrombotic  complications, despite the in-hospital use of standard- or escalated-dose thromboprophylaxis. As a result, numerous studies have focused on understanding the thrombotic tendency in these patients. Whole-blood viscoelastic tests and thrombingeneration assays have demonstrated a hypercoagulable state. In addition, abnormalities in conventional coagulation tests, such as a prolonged prothrombin time (PT), and highly elevated von Willebrand factor (VWF), D-dimer, and fibrinogen levels have been found. Moreover, we have recently shown that the prothrombotic changes found in COVID-19 patients shortly after admission are associated with disease severity and mortality. These data align with the hypothesis that the prothrombotic changes in COVID-19 patients contribute to disease progression, potentially by facilitating pulmonary (micro)thrombosis. Importantly, persistence of symptoms, such as dyspnea and fatigue, have been reported in a proportion of hospitalized and nonhospitalized COVID-19 patients up to 3 months after primary infection. The pathophysiology of this so-called post–COVID-19 syndrome remains largely unknown. We hypothesize that the post–COVID-19 syndrome may involve sustained intrapulmonary activation of coagulation, perhaps driven by residual pulmonary microvascular injury, with ongoing pulmonary microthrombosis as a consequence. To the best of our knowledge, the hemostatic status of COVID-19 patients after hospital discharge has not yet been assessed. Therefore, we studied the hemostatic status of patients with a resolved COVID-19 infection. We have previously reported the hemostatic status of a cohort during hospital admission and these patients were a subset. In this study, we report the hemostatic status of these patients at 4 months after hospital discharge.