Venous Thrombo-Embolism in an Outpatient Vascular Ultrasound Laboratory All-Comers Cohort with Recent COVID-19 Infection

ABSTRACT

Introduction: Inflammatory mechanisms triggered and supported by SARS-CoV-2 infection can increase venous thromb-oembolism (VTE) risk. Aim: The aim of the present comparative study was to report on the incidence of VTE in a prospective consecutive series of COVID-19 negative outpatients referred to our vascular ultrasound laboratory for suspected VTE with (COVID+) or without (COVID–) recent SARS-CoV-2 infection during the COVID-19 pandemic. Methods: All patients included in the present study were assessed by duplex ultrasound for the detection of VTE. The following data were collected for each patient time from first negative swab after COVID-19 infection and VTE diagnosis in COVID+ patients;administration of heparin prophylaxis during COVID-19 infection;presence of venous risk factors (previous VTE episode, chronic venous insufficiency, thrombophilia, recent surgery with prolonged immobilisation, history of malignancy, need for high dose steroid therapy, and dehydration during infection). Rate of VTE was detected and compared between the two groups of COVID+ or COVID– patients by chi square test for categorical data. The presence of risk factors for VTE were analysed as related to VTE occurrence in both groups. Results: From 1 February 2021 to 31 March 2021, 34 patients were included in the study. Among them eight had previous SARS-CoV-2 infection and were negative at the time of investigation. In COVID+ patients, time from first negative swab after COVID-19 infection and VTE diagnosis ranged between 3 and 50 days (mean 17 ± 14.39 days), and 12.5% (n = 1/8) had heparin prophylaxis during infection. Risk factors for VTE were detected in all COVID+ patients and 80.7% (n = 21/26) of COVID– patients. Rate of VTE was 87.5% (n = 7/8) in COVID+ patients and 11.5% (n = 3/26) in COVID– patients (odds ratio 53.66, 95% confidence interval 4.79 – 601.23;p <.001). In the COVID+ population only one patient receiving heparin prophylaxis during infection did not present with VTE. One COVID+ patient presented with both arterial and venous popliteal thrombosis. By comparing directly COVID+ patients with no heparin prophylaxis and venous risk factors (n = 7) to COVID– patients with venous risk factors (n = 21), VTE risk was strongly associated with the presence of previous SARS-CoV-2 infection without proper heparin prophylactic administration (p <.001). Conclusion: In this preliminary series presence of risk factors for VTE and recent SARS-CoV-2 infection with no heparin prophylaxis is strongly associated with VTE occurrence. COVID-19 outpatients should be treated by prophylactic heparin whenever VTE risk factors are detected and duplex ultrasound cannot be performed to exclude a VTE episode, so that physicians treating outpatients should be aware of the VTE risk in those patients. Both arterial and venous conditions prone to thrombosis should be fully assessed in patients when diagnosing a new SARS-CoV-2 infection.