Riccardo Colombo

Background: COVID-19 increases the risk of venous thromboembolism (VTE) through a complex interplay of mechanisms collectively referred to as immunothrombosis. Limited data exist on VTE challenges in the acute setting throughout a dynamic long-term follow-up of COVID-19 patients compared to non-COVID-19 patients. The aim of the study was to investigate acute and long-term management and complications in VTE patients with and without COVID-19. Methods: A prospective, observational, single-center cohort study on VTE patients followed from the acute care stage until 24 months post-diagnosis. Results: 157 patients, 30 with COVID-19-associated VTE and 127 unrelated to COVID-19, were enrolled. The mean follow-up was 10.8 (±8.9) months. COVID-19 patients had fewer comorbidities (1.3 ± 1.29 vs. 2.26 ± 1.68, p < 0.001), a higher proportion of pulmonary embolism at baseline (96.7% vs. 76.4%, p = 0.01), and had a lower probability of remaining on anticoagulant therapy after three months (p < 0.003). The most used initial therapy was low-molecular-weight heparin in 130/157 cases, followed by long-term treatment with direct oral anticoagulants in 123/157. Two (6.7%) COVID-19 vs. three (2.4%) non-COVID-19 patients (p = 0.243) had major hemorrhagic events, all of them within the first three months. Four (3.1%) non-COVID-19 patients had VTE recurrence after six months. Three (2.4%) non-COVID-19 patients developed chronic thromboembolic pulmonary hypertension. There were no fatalities among patients with COVID-19, compared to a mortality of 12/127 (9.4%) in the non-COVID-19 subgroup (p = 0.027). Discussion: Our study offers a comprehensive overview of the evolving nature of VTE management, emphasizing the importance of personalized risk-based approaches, including a limited course of anticoagulation for most COVID-19-associated VTE cases and reduced-dose extended therapy for high-risk subsets.