Background: Venous thromboembolism (VTE) is common among patients with severe coronavirus disease 2019 (COVID-19). Anticoagulation in hospitalized COVID-19 patients has been associated with survival benefit; however, the optimal thromboprophylaxis strategy has not yet been defined. Objective: To identify published guidance reports by national and international societies regarding thromboprophylaxis strategies in COVID-19 patients in different settings (outpatients, hospitalized, post-discharge). Methods: A systematic review of the literature (Pubmed/EMBASE) was conducted independently by two investigators. Results: Among 1942 initially identified articles, 33 guidance documents were included: 20 published by national and 13 by international societies. These documents provide recommendations mainly for hospitalized (97% of reports) and post-discharge (75%) COVID-19 patients, and less so for outpatients (34%). Thrombotic and bleeding risk stratification prior to any treatment decision is the cornerstone of all suggested thromboprophylaxis strategies; 81% of the documents recommend thromboprophylaxis for all hospitalized patients with a prophylactic dosage of low molecular weight heparin irrespective of VTE risk. Intermediate or therapeutic dose intensity is recommended in high VTE risk patients by 56% and 28% of documents, respectively. Mechanical thromboprophylaxis is suggested in case of high bleeding risk or contraindication to pharmacological thromboprophylaxis (59% of documents). Extended pharmacological thromboprophylaxis is recommended for patients with high VTE risk after hospital discharge (63% of documents). For non-hospitalized outpatients, 28% of documents recommend pharmacological thromboprophylaxis for high VTE risk. Conclusion: The current guidance identifies thromboprophylaxis in COVID-19 patients, especially during hospitalization, as of major importance for the prevention of VTE. Recommendations are derived from limited evidence from observational studies.

Coronavirus disease 2019 (COVID-19) does not only affect the respiratory system but appears to be a systemic disease. Venous thromboembolism is a common manifestation in hospitalized patients with COVID-19 with a reported incidence that is significantly higher compared to other acute viral infections. The pathophysiology mechanisms have not been fully explored and autopsy studies might enhance our understanding on this topic. Microthrombi formation occurs mainly in the pulmonary vasculature but can also occur in other organs. The high inflammatory burden related to COVID-19 seems to be associated with the coexisting coagulopathy. Concomitant manifestations of COVID-19, such as severe pneumonia, which has similar clinical presentation with pulmonary embolism (PE), and barriers related to strict isolation protocols are the two main reasons why PE diagnosis might be more challenging in patients with COVID-19. Medical societies have published guidance reports suggesting the administration of prophylactic anticoagulant therapy in hospitalized patients with COVID-19, but several questions regarding the optimal acute and long-term treatment of these patients remain unanswered.

Background: Cardiac injury (CI) is not a rare condition among hospitalized patients with coronavirus disease 2019 . Its prognostic value has been extensively reported through the literature, mainly in the context of observational studies. An impressive number of relevant meta-analyses has been conducted. These meta-analyses present similar and consistent results; yet interesting methodological issues emerge. Methods: A systematic literature search was conducted aiming to identify all relevant meta-analyses on (i) the incidence, and (ii) the prognostic value of CI among hospitalized patients with COVID-19. Results: Among 118 articles initially retrieved, 73 fulfilled the inclusion criteria and were included in the systematic review. Various criteria were used for CI definition mainly based on elevated cardiac biomarkers levels. The most frequently used biomarker was troponin. 30 meta-analyses reported the pooled incidence of CI in hospitalized patients with COVID-19 that varies from 5% to 37%. 32 meta-analyses reported on the association of CI with COVID-19 infection severity, with only 6 of them failing to show a statistically significant association. Finally, 46 meta-analyses investigated the association of CI with mortality and showed that patients with COVID-19 with CI had increased risk for worse prognosis. Four meta-analyses reported pooled adjusted hazard ratios for death in patients with COVID-19 and CI vs those without CI ranging from 1.5 to 3. Conclusions: The impact of CI on the prognosis of hospitalized patients with COVID-19 has gained great interest during the pandemic. Methodological issues such as the inclusion of not peer-reviewed studies, the inclusion of potentially overlapping populations or the inclusion of studies with unadjusted analyses for confounders should be taken into consideration. Despite these limitations, the adverse prognosis of patients with COVID-19 and CI has been consistently demonstrated.