Hypercoagulable state
COVID-19 is associated with a hypercoagulable status.46,47 COVID-19 patients with acute respiratory failure presented a severe hypercoagulability rather than consumptive coagulopathy. Fibrin formation and polymerization may predispose to thrombosis and correlate with a worse outcome.46The incidence of venous thromboembolism could be as high as 25% in COVID-19 patients with severe pneumonia.48 In a different cohort, the composite outcome of symptomatic acute pulmonary embolism, deep-vein thrombosis, ischemic stroke, myocardial infarction, or systemic arterial embolism was 31%.49The stroke rate in COVID patients was around 1-2%.49,50The incidence of stroke is not as high as venous thromboembolism. The evidence is still needed to establish a causal relationship between stroke and COVID-19. The International Society on Thrombosis and Haemosthasis (ISTH) and American Society of Hematology (ASH) recommends prophylactic low molecular weight heparin for venous thromboembolism in all hospitalized COVID-19 patients in the absence of any contraindications.51However, supporting evidence ofprophylactic anticoagulants for stroke in AF patients with COVID-19remains sparse. We do not know whether the anticoagulants in COVID-19 patients with AF should be treated more aggressively even under low CHA₂DS₂-VASc score (0 for male and 1 for female). Hypercoagulable state in severe COVID-19 diseases was frequently observed with concurrent multi-organ failure, which would also significantly increase the risk of bleeding.