Maximum Amplitude Measurement on Thromboelastography Is Inversely Associated with Development of Venous Thromboembolism in Critically Ill Patients with COVID-19 Pneumonia

RATIONALE: Coronavirus disease 2019 (COVID-19) is associated with high rates of venous thromboembolism despite prophylactic anticoagulation. Thromboelastography (TEG) has been suggested as a tool for identifying patients at increased risk of VTE. This study aims to determine if serial TEG evaluation predicts the development of VTE in patients with COVID-19 and respiratory failure admitted to the intensive care unit (ICU). METHODS: We conducted a prospective cohort study of patients admitted to the ICU with COVID-19 and respiratory failure without a prior diagnosis of acute VTE. Patients underwent TEG on days 1, 4, and 6 of ICU admission. The number of hypercoagulable days, defined as elevated TEG maximum amplitude, were recorded. The outcome was time from ICU admission to VTE during the hospital admission. Patients were censored at death and discharge. A Cox proportional hazards model was fit for time to first VTE controlling for patient age, sex, and exposure to antiplatelet agents. RESULTS: A total of 56 patients were enrolled in the study (11 females/45 males);41.1% had a hypercoagulable TEG (MA above the upper limit of normal) on ICU day 1, 55.4% on day 4, and 48.2% on day 6. The primary outcome of VTE occurred in 17 patients (30.4%). The median time from ICU admission to VTE was 7 days (IQR 3-12). Of the 14 patients with hypercoagulable MA on all 3 measured days, 1 patient (7.1%) developed a VTE compared to 15.4% of those with hypercoagulable MA for 2 days (N=13), 30.8% of those hypercoagulable for 1 day (N=13), and 62.5% of patients not hypercoagulable any of the 3 days (N=16). Multivariable Cox-proportional hazards model found that increasing number of hypercoagulable days by MA was associated with a decreased risk of VTE (OR 0.48, CI 0.27-0.85, p=0.01). A Cox proportional hazards regression curve for the number of hypercoagulable days by MA holding all other covariates at their medians is shown in Figure 1. CONCLUSION: In this study, more hypercoagulable days on TEG MA measurement was counterintuitively associated with a decreased risk of VTE in patients with COVID-19 respiratory failure. The normal response to inflammation and infection is upregulation of pro-coagulant acute phase reactants suggesting that increased TEG MA may be physiologic. TEG MA measures below the upper limit of normal are associated with an increased risk of VTE and may mark the development of a consumptive coagulopathy.