Systemic thrombosis in a large cohort of COVID-19 patients despite thromboprophylaxis: a retrospective study

Muñoz-Rivas, Nuria; Abad-Motos, Ane; Mestre-Gómez, Beatriz; Sierra-Hidalgo, Fernando; Cortina-Camarero, Cristina; Lorente-Ramos, Rosa María; Torres-Rubio, Pedro; Arranz-García, Paz; Franco-Moreno, Ana Isabel; Gómez-Mariscal, Eloy; Mauleón-Fernández, Cristina; Alonso-García, Soledad; Rogado, Jacobo; Saez-Vaquero, Teresa; Such-Diaz, Ana; Ryan, Pablo; Moya-Mateo, Eva; Martín-Navarro, Juan A.; Hernández-Rivas, Jose Angel; Torres-Macho, Juan; Churruca, Juan

Background Incidence of thrombotic events associated to Coronavirus disease-2019 (COVID-19) is difficult to assess and reported rates differ significantly. Optimal thromboprophylaxis is unclear. Objectives We aimed to analyze the characteristics of patients with a confirmed thrombotic event including inflammatory and hemostatic parameters, compare patients affected by arterial vs venous events and examine differences between survivors and non-survivors. We reviewed compliance with thromboprophylaxis and explored how the implementation of a severity-adjusted protocol could have influenced outcome. Methods Single-cohort retrospective study of COVID-19 patients admitted, from March 3 to May 3, to the Infanta Leonor University Hospital in Madrid, epicenter of the Spanish outbreak. Results Among 1,127 patients, 80 thrombotic events were diagnosed in 69 patients (6.1% of the entire cohort). 43 patients (62%) suffered venous thromboembolism, 18 (26%) arterial events and 6 (9%) concurrent venous and arterial thrombosis. Most patients (90%) with a confirmed thrombotic event where under low-molecular-weight heparin treatment. Overt disseminated intravascular coagulation (DIC) was rare. Initial ISTH DIC score and pre-event CRP were significantly higher among non-survivors. In multivariate analysis, arterial localization was an independent predictor of mortality (OR=18, 95% CI: 2.4-142, p<.05). Conclusions Despite quasi-universal thromboprophylaxis, COVID-19 lead to a myriad of arterial and venous thrombotic events. Considering the subgroup of patients with thrombotic episodes, arterial events conferred very poor prognosis and an ISTH DIC score ≥3 at presentation was identified as a potential predictor of mortality. Severity-adjusted thromboprophylaxis seemed to decrease the number of events and could have influenced mortality. Randomized controlled trials are eagerly awaited.