Characteristics of Venous Thromboembolism in COVID-19 Patients: A Multicenter Experience from Northern Italy

Background: The liability of patients affected by novel coronavirus disease (COVID-19) to develop venous thromboembolic events is widely acknowledged. However, many particulars of the interactions between the two diseases are still unknown. This study aims to outline the main characteristics of deep venous thrombosis (DVT) and pulmonary embolism (PE) in COVID-19 patients, based on the experience of four high-volume COVID-19 hospitals in Northern Italy. Methods: All cases of COVID-19 in-hospital patients undergoing duplex ultrasound (DUS) for clinically suspected DVT between March 1st and April 25th, 2020, were reviewed. Demographics and clinical data of all patients with confirmed DVT were recorded. Computed tomography pulmonary angiographies of the same population were also examined looking for signs of PE. Results: Of 101 DUS performed, 42 were positive for DVT, 7 for superficial thrombophlebitis, and 24 for PE, 8 of which associated with a DVT. Most had a moderate (43.9%) or mild (16.9%) pneumonia. All venous districts were involved. Time of onset varied greatly, but diagnosis was more frequent in the first two weeks since in-hospital acceptance (73.8%). Most PEs involved the most distal pulmonary vessels, and two-thirds occurred in absence of a recognizable DVT. Conclusions: DVT, thrombophlebitis, and PE are different aspects of COVID-19 procoagulant activity and they can arise regardless of severity of respiratory impairment. All venous districts can be involved, including the pulmonary arteries, where the high number and distribution of the thrombotic lesions without signs of DVT could hint a primitive thrombosis rather than embolism.