190: MONITORING OF HEPARIN ANTICOAGULATION IN ADULT PATIENTS WITH SEVERE COVID

Introduction: Severe COVID increases the risk of thrombotic complications. Therapeutic anticoagulation with unfractionated heparin (UH) is commonly utilized to prevent venous thromboembolism (VTE). Thromboelastography (TEG) provides a dynamic and global assessment of hemostasis, which may be advantageous or complimentary with standard coagulation tests like anti-Xa activity or activated partial thromboplastin time (aPTT). The purpose of this study was to evaluate the correlation between anti-Xa activity and aPTT with the TEG parameters of reaction (R) time and coagulation index (CI) in patients with severe COVID receiving UH. Methods: This was a single-center, retrospective study conducted over a 15-month period (2020-2021). Adult patients with severe COVID receiving UH with ≥1 corresponding TEG and anti-Xa / aPTT samples assessed ≤2 hours of each other were included. The primary endpoint was the correlation between anti-Xa activity and R time. Additional associations were determined for aPTT and R time and anti-Xa activity and aPTT with CI. Pearson’s coefficient was used to evaluate the correlation using a kappa measure of agreement. Results: A total of 423 assessments across 237 patients were included. R time did not correlate with anti-Xa activity (r2=0.032; p< 0.0001) nor aPTT (r2=0.007; p=0.061). CI did not correlate with anti-Xa activity (r2=0.093; p< 0.0001) nor aPTT (r2=0.017; p=0.0073). Overall, 188 (45%) R times and anti-Xa values showed agreement in terms of both demonstrating therapeutic anticoagulation, sub-therapeutic anticoagulation, or supra-therapeutic anticoagulation. Twenty-eight patients (11.8%) and 21 patients (8.9%) developed a clinically relevant bleed or VTE, respectively, but all coagulation and TEG parameters were similar between those with a bleed or VTE and those without. Conclusions: The TEG parameters of R time and CI did not correlate with anti-Xa activity or aPTT for monitoring of intensity of anticoagulation with UH in patients with severe COVID-19. Using TEG in these patients to monitor UH anticoagulation offers no benefit over anti-Xa activity or aPTT. Further research is necessary to address the laboratory tests needed to help with decision-making on anticoagulation dosing in patients with severe COVID.